Internet Engineering Task Force (IETF) S. Lhomme
Request for Comments: 9559
Updates: 8794 M. Bunkus
Category: Standards Track
ISSN: 2070-1721 D. Rice
March 2024
Matroska Media Container Format Specifications
Abstract
This document defines the Matroska audiovisual data container
structure, including definitions of its structural elements,
terminology, vocabulary, and application.
This document updates RFC 8794 to permit the use of a previously
reserved Extensible Binary Meta Language (EBML) Element ID.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9559.
Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Revised BSD License text as described in Section 4.e of the
Trust Legal Provisions and are provided without warranty as described
in the Revised BSD License.
Table of Contents
1. Introduction
2. Status of This Document
3. Notation and Conventions
4. Matroska Overview
4.1. Principles
4.2. Updates to RFC 8794
4.3. Added EBML Constraints
4.4. Design Rules
4.5. Data Layout
5. Matroska Schema
5.1. Segment Element
5.1.1. SeekHead Element
5.1.1.1. Seek Element
5.1.2. Info Element
5.1.2.1. SegmentUUID Element
5.1.2.2. SegmentFilename Element
5.1.2.3. PrevUUID Element
5.1.2.4. PrevFilename Element
5.1.2.5. NextUUID Element
5.1.2.6. NextFilename Element
5.1.2.7. SegmentFamily Element
5.1.2.8. ChapterTranslate Element
5.1.2.9. TimestampScale Element
5.1.2.10. Duration Element
5.1.2.11. DateUTC Element
5.1.2.12. Title Element
5.1.2.13. MuxingApp Element
5.1.2.14. WritingApp Element
5.1.3. Cluster Element
5.1.3.1. Timestamp Element
5.1.3.2. Position Element
5.1.3.3. PrevSize Element
5.1.3.4. SimpleBlock Element
5.1.3.5. BlockGroup Element
5.1.4. Tracks Element
5.1.4.1. TrackEntry Element
5.1.5. Cues Element
5.1.5.1. CuePoint Element
5.1.6. Attachments Element
5.1.6.1. AttachedFile Element
5.1.7. Chapters Element
5.1.7.1. EditionEntry Element
5.1.8. Tags Element
5.1.8.1. Tag Element
6. Matroska Element Ordering
6.1. Top-Level Elements
6.2. CRC-32
6.3. SeekHead
6.4. Cues (Index)
6.5. Info
6.6. Chapters Element
6.7. Attachments
6.8. Tags
7. Matroska Versioning
8. Stream Copy
9. DefaultDecodedFieldDuration
10. Cluster Blocks
10.1. Block Structure
10.2. SimpleBlock Structure
10.3. Block Lacing
10.3.1. No Lacing
10.3.2. Xiph Lacing
10.3.3. EBML Lacing
10.3.4. Fixed-size Lacing
10.3.5. Laced Frames Timestamp
10.4. Random Access Points
11. Timestamps
11.1. Timestamp Ticks
11.1.1. Matroska Ticks
11.1.2. Segment Ticks
11.1.3. Track Ticks
11.2. Block Timestamps
11.3. TimestampScale Rounding
12. Language Codes
13. Country Codes
14. Encryption
15. Image Presentation
15.1. Cropping
15.2. Rotation
16. Segment Position
16.1. Segment Position Exception
16.2. Example of Segment Position
17. Linked Segments
17.1. Hard Linking
17.2. Medium Linking
17.2.1. Linked Duration
17.2.2. Linked Edition
18. Track Flags
18.1. Default Flag
18.2. Forced Flag
18.3. Hearing-Impaired Flag
18.4. Visually Impaired Flag
18.5. Descriptions Flag
18.6. Original Flag
18.7. Commentary Flag
18.8. Track Operation
18.9. Overlay Track
18.10. Multi-planar and 3D Videos
19. Default Track Selection
19.1. Audio Selection
19.2. Subtitle Selection
20. Chapters
20.1. EditionEntry
20.1.1. EditionFlagDefault
20.1.2. Default Edition
20.1.3. EditionFlagOrdered
20.1.3.1. Ordered-Edition and Matroska Segment Linking
20.2. ChapterAtom
20.2.1. ChapterTimeStart
20.2.2. ChapterTimeEnd
20.2.3. Nested Chapters
20.2.4. Nested Chapters in Ordered Chapters
20.2.5. ChapterFlagHidden
20.3. Menu Features
20.4. Physical Types
20.5. Chapter Examples
20.5.1. Example 1: Basic Chaptering
20.5.2. Example 2: Nested Chapters
20.5.2.1. The Micronauts "Bleep To Bleep"
21. Attachments
21.1. Cover Art
21.2. Font Files
22. Cues
22.1. Recommendations
23. Matroska Streaming
23.1. File Access
23.2. Livestreaming
24. Tags
24.1. Tags Precedence
24.2. Tag Levels
25. Implementation Recommendations
25.1. Cluster
25.2. SeekHead
25.3. Optimum Layouts
25.3.1. Optimum Layout for a Muxer
25.3.2. Optimum Layout after Editing Tags
25.3.3. Optimum Layout with Cues at the Front
25.3.4. Optimum Layout for Livestreaming
26. Security Considerations
27. IANA Considerations
27.1. Matroska Element IDs Registry
27.2. Chapter Codec IDs Registry
27.3. Media Types
27.3.1. For Files Containing Video Tracks
27.3.2. For Files Containing Audio Tracks with No Video Tracks
27.3.3. For Files Containing a Stereoscopic Video Track
28. References
28.1. Normative References
28.2. Informative References
Appendix A. Historic Deprecated Elements
A.1. SilentTracks Element
A.2. SilentTrackNumber Element
A.3. BlockVirtual Element
A.4. ReferenceVirtual Element
A.5. Slices Element
A.6. TimeSlice Element
A.7. LaceNumber Element
A.8. FrameNumber Element
A.9. BlockAdditionID Element
A.10. Delay Element
A.11. SliceDuration Element
A.12. ReferenceFrame Element
A.13. ReferenceOffset Element
A.14. ReferenceTimestamp Element
A.15. EncryptedBlock Element
A.16. MinCache Element
A.17. MaxCache Element
A.18. TrackOffset Element
A.19. CodecSettings Element
A.20. CodecInfoURL Element
A.21. CodecDownloadURL Element
A.22. CodecDecodeAll Element
A.23. TrackOverlay Element
A.24. AspectRatioType Element
A.25. GammaValue Element
A.26. FrameRate Element
A.27. ChannelPositions Element
A.28. TrickTrackUID Element
A.29. TrickTrackSegmentUID Element
A.30. TrickTrackFlag Element
A.31. TrickMasterTrackUID Element
A.32. TrickMasterTrackSegmentUID Element
A.33. ContentSignature Element
A.34. ContentSigKeyID Element
A.35. ContentSigAlgo Element
A.36. ContentSigHashAlgo Element
A.37. CueRefCluster Element
A.38. CueRefNumber Element
A.39. CueRefCodecState Element
A.40. FileReferral Element
A.41. FileUsedStartTime Element
A.42. FileUsedEndTime Element
A.43. TagDefaultBogus Element
Authors' Addresses
1. Introduction
Matroska is an audiovisual data container format. It was derived
from a project called [MCF] but diverges from it significantly
because it is based on EBML (Extensible Binary Meta Language)
[RFC8794], a binary derivative of XML. EBML provides significant
advantages in terms of future format extensibility without breaking
file support in parsers reading the previous versions.
First, it is essential to clarify exactly "What an Audio/Video
container is", to avoid any misunderstandings:
* It is NOT a video or audio compression format (codec).
* It is an envelope in which there can be many audio, video, and
subtitles streams, allowing the user to store a complete movie or
CD in a single file.
Matroska is designed with the future in mind. It incorporates
features such as:
* Fast seeking in the file
* Chapter entries
* Full metadata (tags) support
* Selectable subtitle/audio/video streams
* Modularly expandable
* Error resilience (can recover playback even when the stream is
damaged)
* Streamable over the internet and local networks (HTTP [RFC9110],
FTP [RFC0959], SMB [SMB-CIFS], etc.)
* Menus (similar to what DVDs have [DVD-Video])
2. Status of This Document
This document covers Matroska versions 1, 2, 3, and 4. Matroska
version 4 is the current version. Matroska 1 to 3 are no longer
maintained. No new elements are expected in files with version
numbers 1, 2, or 3.
3. Notation and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document defines specific terms in order to define the format
and application of Matroska:
Matroska: A multimedia container format based on Extensible Binary
Meta Language (EBML).
Matroska Reader: A data parser that interprets the semantics of a
Matroska document and creates a way for programs to use Matroska.
Matroska Player: A Matroska Reader with the primary purpose of
playing audiovisual files, including Matroska documents.
Matroska Writer: A data writer that creates Matroska documents.
4. Matroska Overview
4.1. Principles
Matroska is a Document Type of EBML. This specification is dependent
on the EBML Specification [RFC8794]. For an understanding of
Matroska's EBML Schema, see the following sections of [RFC8794] that
cover EBML Element Types (Section 7 of [RFC8794]), EBML Schema
(Section 11.1 of [RFC8794]), and EBML Structure (Section 3 of
[RFC8794]).
4.2. Updates to RFC 8794
Because of an oversight, [RFC8794] reserved EBML ID 0x80, which is
used by deployed Matroska implementations. For this reason, this
specification updates [RFC8794] to make 0x80 a legal EBML ID.
Additionally, this specification makes the following updates:
* Section 17.1 of [RFC8794] (per Errata 7189 [Err7189])
OLD:
| One-octet Element IDs MUST be between 0x81 and 0xFE. These
| items are valuable because they are short, and they need to be
| used for commonly repeated elements. Element IDs are to be
| allocated within this range according to the "RFC Required"
| policy [RFC8126].
|
| The following one-octet Element IDs are RESERVED: 0xFF and
| 0x80.
NEW:
| One-octet Element IDs MUST be between 0x80 and 0xFE. These
| items are valuable because they are short, and they need to be
| used for commonly repeated elements. Element IDs are to be
| allocated within this range according to the "RFC Required"
| policy [RFC8126].
|
| The following one-octet Element ID is RESERVED: 0xFF.
* Section 5 of [RFC8794] (per Errata 7191 [Err7191])
OLD:
+=========================+================+=================+
| Element ID Octet Length | Range of Valid | Number of Valid |
| | Element IDs | Element IDs |
+=========================+================+=================+
| 1 | 0x81 - 0xFE | 126 |
+-------------------------+----------------+-----------------+
NEW:
+=========================+================+=================+
| Element ID Octet Length | Range of Valid | Number of Valid |
| | Element IDs | Element IDs |
+=========================+================+=================+
| 1 | 0x80 - 0xFE | 127 |
+-------------------------+----------------+-----------------+
4.3. Added EBML Constraints
As an EBML Document Type, Matroska adds the following constraints to
the EBML specification:
* The docType of the EBML Header MUST be "matroska".
* The EBMLMaxIDLength of the EBML Header MUST be 4.
* The EBMLMaxSizeLength of the EBML Header MUST be between 1 and 8
inclusive.
4.4. Design Rules
The Root Element and all Top-Level Elements MUST use 4 octets for
their EBML Element ID -- i.e., Segment and direct children of
Segment.
Legacy EBML / Matroska parsers did not handle Empty Elements
properly. Elements were present in the file, but had a length of 0.
They always assumed the value was 0 for integers/dates or 0x0p+0, the
textual expression of floats using the [ISO9899] format, no matter
the default value of the element which should have been used instead.
Therefore, Matroska Writers MUST NOT use EBML Empty Elements, if the
element has a default value that is not 0 for integers/dates and
0x0p+0 for floats.
When adding new elements to Matroska, these rules apply:
* A non-mandatory integer/date Element MUST NOT have a default value
other than 0.
* A non-mandatory float Element MUST NOT have a default value other
than 0x0p+0.
* A non-mandatory string Element MUST NOT have a default value, as
empty strings cannot be defined in the XML Schema.
4.5. Data Layout
A Matroska file MUST be composed of at least one EBML Document using
the Matroska Document Type. Each EBML Document MUST start with an
EBML Header and MUST be followed by the EBML Root Element, defined as
a Segment in Matroska. Matroska defines several Top-Level Elements
that may occur within the Segment.
As an example, a simple Matroska file consisting of a single EBML
Document could be represented like this:
* EBML Header
* Segment
A more complex Matroska file consisting of an EBML Stream (containing
two EBML Documents) could be represented like this:
* EBML Header
* Segment
* EBML Header
* Segment
The following diagram represents a simple Matroska file, comprised of
an EBML Document with an EBML Header, a Segment Element (the Root
Element), and all eight Matroska Top-Level Elements. In the
following diagrams of this section, horizontal spacing expresses a
parent-child relationship between Matroska Elements (e.g., the Info
Element is contained within the Segment Element), whereas vertical
alignment represents the storage order within the file.
+-------------+
| EBML Header |
+---------------------------+
| Segment | SeekHead |
| |-------------|
| | Info |
| |-------------|
| | Tracks |
| |-------------|
| | Chapters |
| |-------------|
| | Cluster |
| |-------------|
| | Cues |
| |-------------|
| | Attachments |
| |-------------|
| | Tags |
+---------------------------+
Figure 1: Basic Layout of a Matroska File
The Matroska EBML Schema defines eight Top-Level Elements:
* SeekHead (Section 6.3)
* Info (Section 6.5)
* Tracks (Section 18)
* Chapters (Section 20)
* Cluster (Section 10)
* Cues (Section 22)
* Attachments (Section 21)
* and Tags (Section 6.8)
The SeekHead Element (also known as MetaSeek) contains an index of
Top-Level Elements locations within the Segment. Use of the SeekHead
Element is RECOMMENDED. Without a SeekHead Element, a Matroska
parser would have to search the entire file to find all of the other
Top-Level Elements. This is due to Matroska's flexible ordering
requirements; for instance, it is acceptable for the Chapters Element
to be stored after the Cluster Element.
+--------------------------------+
| SeekHead | Seek | SeekID |
| | |--------------|
| | | SeekPosition |
+--------------------------------+
Figure 2: Representation of a SeekHead Element
The Info Element contains vital information for identifying the whole
Segment. This includes the title for the Segment, a randomly
generated unique identifier (UID), and the UID(s) of any linked
Segment Elements.
+-------------------------+
| Info | SegmentUUID |
| |------------------|
| | SegmentFilename |
| |------------------|
| | PrevUUID |
| |------------------|
| | PrevFilename |
| |------------------|
| | NextUUID |
| |------------------|
| | NextFilename |
| |------------------|
| | SegmentFamily |
| |------------------|
| | ChapterTranslate |
| |------------------|
| | TimestampScale |
| |------------------|
| | Duration |
| |------------------|
| | DateUTC |
| |------------------|
| | Title |
| |------------------|
| | MuxingApp |
| |------------------|
| | WritingApp |
|-------------------------|
Figure 3: Representation of an Info Element and Its Child Elements
The Tracks Element defines the technical details for each track and
can store the name, number, UID, language, and type (audio, video,
subtitles, etc.) of each track. For example, the Tracks Element MAY
store information about the resolution of a video track or a sample
rate of an audio track.
The Tracks Element MUST identify all the data needed by the codec to
decode the data of the specified track. However, the data required
is contingent on the codec used for the track. For example, a Track
Element for uncompressed audio only requires the audio bit rate to be
present. A codec such as AC-3 would require that the CodecID Element
be present for all tracks, as it is the primary way to identify which
codec to use to decode the track.
+------------------------------------+
| Tracks | TrackEntry | TrackNumber |
| | |--------------|
| | | TrackUID |
| | |--------------|
| | | TrackType |
| | |--------------|
| | | Name |
| | |--------------|
| | | Language |
| | |--------------|
| | | CodecID |
| | |--------------|
| | | CodecPrivate |
| | |--------------|
| | | CodecName |
| | |----------------------------------+
| | | Video | FlagInterlaced |
| | | |-------------------|
| | | | FieldOrder |
| | | |-------------------|
| | | | StereoMode |
| | | |-------------------|
| | | | AlphaMode |
| | | |-------------------|
| | | | PixelWidth |
| | | |-------------------|
| | | | PixelHeight |
| | | |-------------------|
| | | | DisplayWidth |
| | | |-------------------|
| | | | DisplayHeight |
| | | |-------------------|
| | | | AspectRatioType |
| | | |-------------------|
| | | | Color |
| | |----------------------------------|
| | | Audio | SamplingFrequency |
| | | |-------------------|
| | | | Channels |
| | | |-------------------|
| | | | BitDepth |
|--------------------------------------------------------|
Figure 4: Representation of the Tracks Element and a Selection of Its
Descendant Elements
The Chapters Element lists all of the chapters. Chapters set
predefined points to jump to in video or audio.
+-----------------------------------------+
| Chapters | Edition | EditionUID |
| | Entry |--------------------|
| | | EditionFlagDefault |
| | |--------------------|
| | | EditionFlagOrdered |
| | |---------------------------------+
| | | ChapterAtom | ChapterUID |
| | | |-------------------|
| | | | ChapterStringUID |
| | | |-------------------|
| | | | ChapterTimeStart |
| | | |-------------------|
| | | | ChapterTimeEnd |
| | | |-------------------|
| | | | ChapterFlagHidden |
| | | |-------------------------------+
| | | | ChapterDisplay | ChapString |
| | | | |--------------|
| | | | | ChapLanguage |
+------------------------------------------------------------------+
Figure 5: Representation of the Chapters Element and a Selection
of Its Descendant Elements
Cluster Elements contain the content for each track, e.g., video
frames. A Matroska file SHOULD contain at least one Cluster Element.
In the rare case it doesn't, there should be a form of Segment
linking with other Segments, possibly using Chapters, see Section 17.
The Cluster Element helps to break up SimpleBlock or BlockGroup
Elements and helps with seeking and error protection. Every Cluster
Element MUST contain a Timestamp Element. This SHOULD be the
Timestamp Element used to play the first Block in the Cluster
Element, unless a different value is needed to accommodate for more
Blocks; see Section 11.2.
Cluster Elements contain one or more block element, such as
BlockGroup or SimpleBlock elements. In some situations, a Cluster
Element MAY contain no block element, e.g., in a live recording when
no data has been collected.
A BlockGroup Element MAY contain a Block of data and any information
relating directly to that Block.
+--------------------------+
| Cluster | Timestamp |
| |----------------|
| | Position |
| |----------------|
| | PrevSize |
| |----------------|
| | SimpleBlock |
| |----------------|
| | BlockGroup |
+--------------------------+
Figure 6: Representation of a Cluster Element and Its Immediate
Child Elements
+----------------------------------+
| Block | Portion of | Data Type |
| | a Block | - Bit Flag |
| |--------------------------+
| | Header | TrackNumber |
| | |-------------|
| | | Timestamp |
| | |-------------|
| | | Flags |
| | | - Gap |
| | | - Lacing |
| | | - Reserved |
| |--------------------------|
| | Optional | FrameSize |
| |--------------------------|
| | Data | Frame |
+----------------------------------+
Figure 7: Representation of the Block Element Structure
Each Cluster MUST contain exactly one Timestamp Element. The
Timestamp Element value MUST be stored once per Cluster. The
Timestamp Element in the Cluster is relative to the entire Segment.
The Timestamp Element SHOULD be the first Element in the Cluster it
belongs to, or the second Element if that Cluster contains a CRC-32
element (Section 6.2)
Additionally, the Block contains an offset that, when added to the
Cluster's Timestamp Element value, yields the Block's effective
timestamp. Therefore, the timestamp in the Block itself is relative
to the Timestamp Element in the Cluster. For example, if the
Timestamp Element in the Cluster is set to 10 seconds and a Block in
that Cluster is supposed to be played 12 seconds into the clip, the
timestamp in the Block would be set to 2 seconds.
The ReferenceBlock in the BlockGroup is used instead of the basic
"P-frame"/"B-frame" description. Instead of simply saying that this
Block depends on the Block directly before or directly after, the
Timestamp of the necessary Block is used. Because there can be as
many ReferenceBlock Elements as necessary for a Block, it allows for
some extremely complex referencing.
The Cues Element is used to seek when playing back a file by
providing a temporal index for some of the Tracks. It is similar to
the SeekHead Element, but is used for seeking to a specific time when
playing back the file. It is possible to seek without this element,
but it is much more difficult because a Matroska Reader would have to
"hunt and peck" through the file to look for the correct timestamp.
The Cues Element SHOULD contain at least one CuePoint Element. Each
CuePoint Element stores the position of the Cluster that contains the
BlockGroup or SimpleBlock Element. The timestamp is stored in the
CueTime Element and the location is stored in the CueTrackPositions
Element.
The Cues Element is flexible. For instance, the Cues Element can be
used to index every single timestamp of every Block or they can be
indexed selectively.
+-------------------------------------+
| Cues | CuePoint | CueTime |
| | |-------------------|
| | | CueTrackPositions |
| |------------------------------|
| | CuePoint | CueTime |
| | |-------------------|
| | | CueTrackPositions |
+-------------------------------------+
Figure 8: Representation of a Cues Element and Two Levels of Its
Descendant Elements
The Attachments Element is for attaching files to a Matroska file,
such as pictures, fonts, web pages, etc.
+------------------------------------------------+
| Attachments | AttachedFile | FileDescription |
| | |-------------------|
| | | FileName |
| | |-------------------|
| | | FileMediaType |
| | |-------------------|
| | | FileData |
| | |-------------------|
| | | FileUID |
| | |-------------------|
| | | FileName |
| | |-------------------|
| | | FileReferral |
| | |-------------------|
| | | FileUsedStartTime |
| | |-------------------|
| | | FileUsedEndTime |
+------------------------------------------------+
Figure 9: Representation of an Attachments Element
The Tags Element contains metadata that describes the Segment and
potentially its Tracks, Chapters, and Attachments. Each Track or
Chapter that those tags applies to has its UID listed in the Tags.
The Tags contain all extra information about the file: scriptwriters,
singers, actors, directors, titles, edition, price, dates, genre,
comments, etc. Tags can contain their values in multiple languages.
For example, a movie's "title" Tag might contain both the original
English title as well as the German title.
+-------------------------------------------+
| Tags | Tag | Targets | TargetTypeValue |
| | | |------------------|
| | | | TargetType |
| | | |------------------|
| | | | TagTrackUID |
| | | |------------------|
| | | | TagEditionUID |
| | | |------------------|
| | | | TagChapterUID |
| | | |------------------|
| | | | TagAttachmentUID |
| | |------------------------------|
| | | SimpleTag | TagName |
| | | |------------------|
| | | | TagLanguage |
| | | |------------------|
| | | | TagDefault |
| | | |------------------|
| | | | TagString |
| | | |------------------|
| | | | TagBinary |
| | | |------------------|
| | | | SimpleTag |
+-------------------------------------------+
Figure 10: Representation of a Tags Element and Three Levels of
Its Children Elements
5. Matroska Schema
This specification includes an EBML Schema that defines the Elements
and structure of Matroska using the EBML Schema elements and
attributes defined in Section 11.1 of [RFC8794]. The EBML Schema
defines every valid Matroska element in a manner defined by the EBML
specification.
Attributes using their default value, such as minOccurs, minver,
etc., or attributes with undefined values, such length, maxver, etc.,
are omitted.
The definitions of each Matroska Element is provided below.
5.1. Segment Element
id / type: 0x18538067 / master
unknownsizeallowed: True
path: \Segment
minOccurs / maxOccurs: 1 / 1
definition: The Root Element that contains all other Top-Level
Elements; see Section 4.5.
5.1.1. SeekHead Element
id / type: 0x114D9B74 / master
path: \Segment\SeekHead
maxOccurs: 2
definition: Contains seeking information of Top-Level Elements; see
Section 4.5.
5.1.1.1. Seek Element
id / type: 0x4DBB / master
path: \Segment\SeekHead\Seek
minOccurs: 1
definition: Contains a single seek entry to an EBML Element.
5.1.1.1.1. SeekID Element
id / type: 0x53AB / binary
length: 4
path: \Segment\SeekHead\Seek\SeekID
minOccurs / maxOccurs: 1 / 1
definition: The binary EBML ID of a Top-Level Element.
5.1.1.1.2. SeekPosition Element
id / type: 0x53AC / uinteger
path: \Segment\SeekHead\Seek\SeekPosition
minOccurs / maxOccurs: 1 / 1
definition: The Segment Position (Section 16) of a Top-Level
Element.
5.1.2. Info Element
id / type: 0x1549A966 / master
path: \Segment\Info
minOccurs / maxOccurs: 1 / 1
recurring: True
definition: Contains general information about the Segment.
5.1.2.1. SegmentUUID Element
id / type: 0x73A4 / binary
length: 16
path: \Segment\Info\SegmentUUID
maxOccurs: 1
definition: A randomly generated UID that identifies the Segment
amongst many others (128 bits). It is equivalent to a Universally
Unique Identifier (UUID) v4 [RFC4122] with all bits randomly (or
pseudorandomly) chosen. An actual UUID v4 value, where some bits
are not random, MAY also be used.
usage notes: If the Segment is a part of a Linked Segment, then this
Element is REQUIRED. The value of the UID MUST contain at least
one bit set to 1.
5.1.2.2. SegmentFilename Element
id / type: 0x7384 / utf-8
path: \Segment\Info\SegmentFilename
maxOccurs: 1
definition: A filename corresponding to this Segment.
5.1.2.3. PrevUUID Element
id / type: 0x3CB923 / binary
length: 16
path: \Segment\Info\PrevUUID
maxOccurs: 1
definition: An ID used that identifies the previous Segment of a
Linked Segment.
usage notes: If the Segment is a part of a Linked Segment that uses
Hard Linking (Section 17.1), then either the PrevUUID or the
NextUUID Element is REQUIRED. If a Segment contains a PrevUUID,
but not a NextUUID, then it MAY be considered as the last Segment
of the Linked Segment. The PrevUUID MUST NOT be equal to the
SegmentUUID.
5.1.2.4. PrevFilename Element
id / type: 0x3C83AB / utf-8
path: \Segment\Info\PrevFilename
maxOccurs: 1
definition: A filename corresponding to the file of the previous
Linked Segment.
usage notes: Provision of the previous filename is for display
convenience, but PrevUUID SHOULD be considered authoritative for
identifying the previous Segment in a Linked Segment.
5.1.2.5. NextUUID Element
id / type: 0x3EB923 / binary
length: 16
path: \Segment\Info\NextUUID
maxOccurs: 1
definition: An ID that identifies the next Segment of a Linked
Segment.
usage notes: If the Segment is a part of a Linked Segment that uses
Hard Linking (Section 17.1), then either the PrevUUID or the
NextUUID Element is REQUIRED. If a Segment contains a NextUUID,
but not a PrevUUID, then it MAY be considered as the first Segment
of the Linked Segment. The NextUUID MUST NOT be equal to the
SegmentUUID.
5.1.2.6. NextFilename Element
id / type: 0x3E83BB / utf-8
path: \Segment\Info\NextFilename
maxOccurs: 1
definition: A filename corresponding to the file of the next Linked
Segment.
usage notes: Provision of the next filename is for display
convenience, but NextUUID SHOULD be considered authoritative for
identifying the Next Segment.
5.1.2.7. SegmentFamily Element
id / type: 0x4444 / binary
length: 16
path: \Segment\Info\SegmentFamily
definition: A UID that all Segments of a Linked Segment MUST share
(128 bits). It is equivalent to a UUID v4 [RFC4122] with all bits
randomly (or pseudo-randomly) chosen. An actual UUID v4 value,
where some bits are not random, MAY also be used.
usage notes: If the Segment Info contains a ChapterTranslate
element, this Element is REQUIRED.
5.1.2.8. ChapterTranslate Element
id / type: 0x6924 / master
path: \Segment\Info\ChapterTranslate
definition: The mapping between this Segment and a Segment value in
the given Chapter Codec.
rationale: Chapter Codec may need to address different Segments, but
they may not know of the way to identify such Segment when stored
in Matroska. This element and its child elements add a way to map
the internal Segments known to the Chapter Codec to the Segment
IDs in Matroska. This allows remuxing a file with Chapter Codec
without changing the content of the codec data and just the
Segment mapping.
5.1.2.8.1. ChapterTranslateID Element
id / type: 0x69A5 / binary
path: \Segment\Info\ChapterTranslate\ChapterTranslateID
minOccurs / maxOccurs: 1 / 1
definition: The binary value used to represent this Segment in the
chapter codec data. The format depends on the ChapProcessCodecID
used; see Section 5.1.7.1.4.15.
5.1.2.8.2. ChapterTranslateCodec Element
id / type: 0x69BF / uinteger
path: \Segment\Info\ChapterTranslate\ChapterTranslateCodec
minOccurs / maxOccurs: 1 / 1
definition: This ChapterTranslate applies to this chapter codec of
the given chapter edition(s); see Section 5.1.7.1.4.15.
defined values:
+=======+=================+============================+
| value | label | definition |
+=======+=================+============================+
| 0 | Matroska Script | Chapter commands using the |
| | | Matroska Script codec. |
+-------+-----------------+----------------------------+
| 1 | DVD-menu | Chapter commands using the |
| | | DVD-like codec. |
+-------+-----------------+----------------------------+
Table 1: ChapterTranslateCodec Values
5.1.2.8.3. ChapterTranslateEditionUID Element
id / type: 0x69FC / uinteger
path: \Segment\Info\ChapterTranslate\ChapterTranslateEditionUID
definition: Specify a chapter edition UID on which this
ChapterTranslate applies.
usage notes: When no ChapterTranslateEditionUID is specified in the
ChapterTranslate, the ChapterTranslate applies to all chapter
editions found in the Segment using the given
ChapterTranslateCodec.
5.1.2.9. TimestampScale Element
id / type / default: 0x2AD7B1 / uinteger / 1000000
range: not 0
path: \Segment\Info\TimestampScale
minOccurs / maxOccurs: 1 / 1
definition: Base unit for Segment Ticks and Track Ticks in
nanoseconds. A TimestampScale value of 1000000 means scaled
timestamps in the Segment are expressed in milliseconds; see
Section 11 on how to interpret timestamps.
5.1.2.10. Duration Element
id / type: 0x4489 / float
range: > 0x0p+0
path: \Segment\Info\Duration
maxOccurs: 1
definition: Duration of the Segment expressed in Segment Ticks,
which are based on TimestampScale; see Section 11.1.
5.1.2.11. DateUTC Element
id / type: 0x4461 / date
path: \Segment\Info\DateUTC
maxOccurs: 1
definition: The date and time that the Segment was created by the
muxing application or library.
5.1.2.12. Title Element
id / type: 0x7BA9 / utf-8
path: \Segment\Info\Title
maxOccurs: 1
definition: General name of the Segment.
5.1.2.13. MuxingApp Element
id / type: 0x4D80 / utf-8
path: \Segment\Info\MuxingApp
minOccurs / maxOccurs: 1 / 1
definition: Muxing application or library (example: "libmatroska-
0.4.3").
usage notes: Include the full name of the application or library
followed by the version number.
5.1.2.14. WritingApp Element
id / type: 0x5741 / utf-8
path: \Segment\Info\WritingApp
minOccurs / maxOccurs: 1 / 1
definition: Writing application (example: "mkvmerge-0.3.3").
usage notes: Include the full name of the application followed by
the version number.
5.1.3. Cluster Element
id / type: 0x1F43B675 / master
unknownsizeallowed: True
path: \Segment\Cluster
definition: The Top-Level Element containing the (monolithic) Block
structure.
5.1.3.1. Timestamp Element
id / type: 0xE7 / uinteger
path: \Segment\Cluster\Timestamp
minOccurs / maxOccurs: 1 / 1
definition: Absolute timestamp of the cluster expressed in Segment
Ticks, which are based on TimestampScale; see Section 11.1.
usage notes: This element SHOULD be the first child element of the
Cluster it belongs to or the second child element if that Cluster
contains a CRC-32 element (Section 6.2).
5.1.3.2. Position Element
id / type: 0xA7 / uinteger
path: \Segment\Cluster\Position
maxOccurs: 1
maxver: 4
definition: The Segment Position of the Cluster in the Segment (0 in
live streams). It might help to resynchronise the offset on
damaged streams.
5.1.3.3. PrevSize Element
id / type: 0xAB / uinteger
path: \Segment\Cluster\PrevSize
maxOccurs: 1
definition: Size of the previous Cluster in octets. Can be useful
for backward playing.
5.1.3.4. SimpleBlock Element
id / type: 0xA3 / binary
path: \Segment\Cluster\SimpleBlock
minver: 2
definition: Similar to Block, see Section 10.1, but without all the
extra information, mostly used to reduced overhead when no extra
feature is needed; see Section 10.2 on SimpleBlock Structure.
5.1.3.5. BlockGroup Element
id / type: 0xA0 / master
path: \Segment\Cluster\BlockGroup
definition: Basic container of information containing a single Block
and information specific to that Block.
5.1.3.5.1. Block Element
id / type: 0xA1 / binary
path: \Segment\Cluster\BlockGroup\Block
minOccurs / maxOccurs: 1 / 1
definition: Block containing the actual data to be rendered and a
timestamp relative to the Cluster Timestamp; see Section 10.1 on
Block Structure.
5.1.3.5.2. BlockAdditions Element
id / type: 0x75A1 / master
path: \Segment\Cluster\BlockGroup\BlockAdditions
maxOccurs: 1
definition: Contains additional binary data to complete the main
one; see the Codec BlockAdditions section of [MatroskaCodec] for
more information. An EBML parser that has no knowledge of the
Block structure could still see and use/skip this data.
5.1.3.5.2.1. BlockMore Element
id / type: 0xA6 / master
path: \Segment\Cluster\BlockGroup\BlockAdditions\BlockMore
minOccurs: 1
definition: Contains the BlockAdditional and some parameters.
5.1.3.5.2.2. BlockAdditional Element
id / type: 0xA5 / binary
path: \Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\BlockAddi
tional
minOccurs / maxOccurs: 1 / 1
definition: Interpreted by the codec as it wishes (using the
BlockAddID).
5.1.3.5.2.3. BlockAddID Element
id / type / default: 0xEE / uinteger / 1
range: not 0
path: \Segment\Cluster\BlockGroup\BlockAdditions\BlockMore\BlockAddI
D
minOccurs / maxOccurs: 1 / 1
definition: An ID that identifies how to interpret the
BlockAdditional data; see Section 4.1.5 of [MatroskaCodec] for
more information. A value of 1 indicates that the meaning of the
BlockAdditional data is defined by the codec. Any other value
indicates the meaning of the BlockAdditional data is found in the
BlockAddIDType found in the TrackEntry.
usage notes: Each BlockAddID value MUST be unique between all
BlockMore elements found in a BlockAdditions.
usage notes: To keep MaxBlockAdditionID as low as possible, small
values SHOULD be used.
5.1.3.5.3. BlockDuration Element
id / type: 0x9B / uinteger
path: \Segment\Cluster\BlockGroup\BlockDuration
minOccurs / maxOccurs: see implementation notes / 1
definition: The duration of the Block expressed in Track Ticks; see
Section 11.1. The BlockDuration Element can be useful at the end
of a Track to define the duration of the last frame (as there is
no subsequent Block available), or when there is a break in a
track like there is for subtitle tracks.
notes:
+===========+===================================================+
| attribute | note |
+===========+===================================================+
| minOccurs | BlockDuration MUST be set (minOccurs=1) if the |
| | associated TrackEntry stores a DefaultDuration |
| | value. |
+-----------+---------------------------------------------------+
| default | When not written and with no DefaultDuration, the |
| | value is assumed to be the difference between the |
| | timestamp of this Block and the timestamp of the |
| | next Block in "display" order (not coding order). |
+-----------+---------------------------------------------------+
Table 2: BlockDuration Implementation Notes
5.1.3.5.4. ReferencePriority Element
id / type / default: 0xFA / uinteger / 0
path: \Segment\Cluster\BlockGroup\ReferencePriority
minOccurs / maxOccurs: 1 / 1
definition: This frame is referenced and has the specified cache
priority. In cache, only a frame of the same or higher priority
can replace this frame. A value of f0 means the frame is not
referenced.
5.1.3.5.5. ReferenceBlock Element
id / type: 0xFB / integer
path: \Segment\Cluster\BlockGroup\ReferenceBlock
definition: A timestamp value, relative to the timestamp of the
Block in this BlockGroup, expressed in Track Ticks; see
Section 11.1. This is used to reference other frames necessary to
decode this frame. The relative value SHOULD correspond to a
valid Block that this Block depends on. Historically, Matroska
Writers didn't write the actual Block(s) that this Block depends
on; however, they did write _some_ Block(s) in the past.
The value "0" MAY also be used to signify that this Block cannot be
decoded on its own, but without knowledge of which Block is
necessary. In this case, other ReferenceBlock Elements MUST NOT be
found in the same BlockGroup.
If the BlockGroup doesn't have a ReferenceBlock element, then the
Block it contains can be decoded without using any other Block data.
5.1.3.5.6. CodecState Element
id / type: 0xA4 / binary
path: \Segment\Cluster\BlockGroup\CodecState
maxOccurs: 1
minver: 2
definition: The new codec state to use. Data interpretation is
private to the codec. This information SHOULD always be
referenced by a seek entry.
5.1.3.5.7. DiscardPadding Element
id / type: 0x75A2 / integer
path: \Segment\Cluster\BlockGroup\DiscardPadding
maxOccurs: 1
minver: 4
definition: Duration of the silent data added to the Block expressed
in Matroska Ticks -- i.e., in nanoseconds; see Section 11.1
(padding at the end of the Block for positive values and at the
beginning of the Block for negative values). The duration of
DiscardPadding is not calculated in the duration of the TrackEntry
and SHOULD be discarded during playback.
5.1.4. Tracks Element
id / type: 0x1654AE6B / master
path: \Segment\Tracks
maxOccurs: 1
recurring: True
definition: A Top-Level Element of information with many tracks
described.
5.1.4.1. TrackEntry Element
id / type: 0xAE / master
path: \Segment\Tracks\TrackEntry
minOccurs: 1
definition: Describes a track with all Elements.
5.1.4.1.1. TrackNumber Element
id / type: 0xD7 / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\TrackNumber
minOccurs / maxOccurs: 1 / 1
definition: The track number as used in the Block Header.
5.1.4.1.2. TrackUID Element
id / type: 0x73C5 / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\TrackUID
minOccurs / maxOccurs: 1 / 1
definition: A UID that identifies the Track.
stream copy: True (Section 8)
5.1.4.1.3. TrackType Element
id / type: 0x83 / uinteger
path: \Segment\Tracks\TrackEntry\TrackType
minOccurs / maxOccurs: 1 / 1
definition: The TrackType defines the type of each frame found in
the Track. The value SHOULD be stored on 1 octet.
defined values:
+=======+==========+==========================================+
| value | label | contents of each frame |
+=======+==========+==========================================+
| 1 | video | An image. |
+-------+----------+------------------------------------------+
| 2 | audio | Audio samples. |
+-------+----------+------------------------------------------+
| 3 | complex | A mix of different other TrackType. The |
| | | codec needs to define how the Matroska |
| | | Player should interpret such data. |
+-------+----------+------------------------------------------+
| 16 | logo | An image to be rendered over the video |
| | | track(s). |
+-------+----------+------------------------------------------+
| 17 | subtitle | Subtitle or closed caption data to be |
| | | rendered over the video track(s). |
+-------+----------+------------------------------------------+
| 18 | buttons | Interactive button(s) to be rendered |
| | | over the video track(s). |
+-------+----------+------------------------------------------+
| 32 | control | Metadata used to control the player of |
| | | the Matroska Player. |
+-------+----------+------------------------------------------+
| 33 | metadata | Timed metadata that can be passed on to |
| | | the Matroska Player. |
+-------+----------+------------------------------------------+
Table 3: TrackType Values
stream copy: True (Section 8)
5.1.4.1.4. FlagEnabled Element
id / type / default: 0xB9 / uinteger / 1
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagEnabled
minOccurs / maxOccurs: 1 / 1
minver: 2
definition: Set to 1 if the track is usable. It is possible to turn
a track that is not usable into a usable track using chapter
codecs or control tracks.
5.1.4.1.5. FlagDefault Element
id / type / default: 0x88 / uinteger / 1
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagDefault
minOccurs / maxOccurs: 1 / 1
definition: Set if the track (audio, video or subs) is eligible for
automatic selection by the player; see Section 19 for more
details.
5.1.4.1.6. FlagForced Element
id / type / default: 0x55AA / uinteger / 0
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagForced
minOccurs / maxOccurs: 1 / 1
definition: Applies only to subtitles. Set if the track is eligible
for automatic selection by the player if it matches the user's
language preference, even if the user's preferences wouldn't
normally enable subtitles with the selected audio track; this can
be used for tracks containing only translations of audio in
foreign languages or on-screen text. See Section 19 for more
details.
5.1.4.1.7. FlagHearingImpaired Element
id / type: 0x55AB / uinteger
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagHearingImpaired
maxOccurs: 1
minver: 4
definition: Set to 1 if and only if the track is suitable for users
with hearing impairments.
5.1.4.1.8. FlagVisualImpaired Element
id / type: 0x55AC / uinteger
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagVisualImpaired
maxOccurs: 1
minver: 4
definition: Set to 1 if and only if the track is suitable for users
with visual impairments.
5.1.4.1.9. FlagTextDescriptions Element
id / type: 0x55AD / uinteger
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagTextDescriptions
maxOccurs: 1
minver: 4
definition: Set to 1 if and only if the track contains textual
descriptions of video content.
5.1.4.1.10. FlagOriginal Element
id / type: 0x55AE / uinteger
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagOriginal
maxOccurs: 1
minver: 4
definition: Set to 1 if and only if the track is in the content's
original language.
5.1.4.1.11. FlagCommentary Element
id / type: 0x55AF / uinteger
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagCommentary
maxOccurs: 1
minver: 4
definition: Set to 1 if and only if the track contains commentary.
5.1.4.1.12. FlagLacing Element
id / type / default: 0x9C / uinteger / 1
range: 0-1
path: \Segment\Tracks\TrackEntry\FlagLacing
minOccurs / maxOccurs: 1 / 1
definition: Set to 1 if the track MAY contain blocks that use
lacing. When set to 0, all blocks MUST have their lacing flags
set to No lacing; see Section 10.3 on Block Lacing.
5.1.4.1.13. DefaultDuration Element
id / type: 0x23E383 / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\DefaultDuration
maxOccurs: 1
definition: Number of nanoseconds per frame expressed in Matroska
Ticks -- i.e., in nanoseconds; see Section 11.1 ("frame" in terms
of Matroska -- one Element put into a (Simple)Block).
stream copy: True (Section 8)
5.1.4.1.14. DefaultDecodedFieldDuration Element
id / type: 0x234E7A / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\DefaultDecodedFieldDuration
maxOccurs: 1
minver: 4
definition: The period between two successive fields at the output
of the decoding process expressed in Matroska Ticks -- i.e., in
nanoseconds; see Section 11.1. see Section 9 for more information
stream copy: True (Section 8)
5.1.4.1.15. TrackTimestampScale Element
id / type / default: 0x23314F / float / 0x1p+0
range: > 0x0p+0
path: \Segment\Tracks\TrackEntry\TrackTimestampScale
minOccurs / maxOccurs: 1 / 1
maxver: 3
definition: The scale to apply on this track to work at a normal
speed in relation with other tracks (mostly used to adjust video
speed when the audio length differs).
stream copy: True (Section 8)
5.1.4.1.16. MaxBlockAdditionID Element
id / type / default: 0x55EE / uinteger / 0
path: \Segment\Tracks\TrackEntry\MaxBlockAdditionID
minOccurs / maxOccurs: 1 / 1
definition: The maximum value of BlockAddID (Section 5.1.3.5.2.3).
A value 0 means there is no BlockAdditions (Section 5.1.3.5.2) for
this track.
5.1.4.1.17. BlockAdditionMapping Element
id / type: 0x41E4 / master
path: \Segment\Tracks\TrackEntry\BlockAdditionMapping
minver: 4
definition: Contains elements that extend the track format by adding
content either to each frame, with BlockAddID
(Section 5.1.3.5.2.3), or to the track as a whole with
BlockAddIDExtraData.
5.1.4.1.17.1. BlockAddIDValue Element
id / type: 0x41F0 / uinteger
range: >=2
path: \Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDValu
e
maxOccurs: 1
minver: 4
definition: If the track format extension needs content beside
frames, the value refers to the BlockAddID (Section 5.1.3.5.2.3)
value being described.
usage notes: To keep MaxBlockAdditionID as low as possible, small
values SHOULD be used.
5.1.4.1.17.2. BlockAddIDName Element
id / type: 0x41A4 / string
path: \Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDName
maxOccurs: 1
minver: 4
definition: A human-friendly name describing the type of
BlockAdditional data as defined by the associated Block Additional
Mapping.
5.1.4.1.17.3. BlockAddIDType Element
id / type / default: 0x41E7 / uinteger / 0
path: \Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDType
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: Stores the registered identifier of the Block Additional
Mapping to define how the BlockAdditional data should be handled.
usage notes: If BlockAddIDType is 0, BlockAddIDValue and
corresponding BlockAddID values MUST be 1.
5.1.4.1.17.4. BlockAddIDExtraData Element
id / type: 0x41ED / binary
path: \Segment\Tracks\TrackEntry\BlockAdditionMapping\BlockAddIDExtr
aData
maxOccurs: 1
minver: 4
definition: Extra binary data that the BlockAddIDType can use to
interpret the BlockAdditional data. The interpretation of the
binary data depends on the BlockAddIDType value and the
corresponding Block Additional Mapping.
5.1.4.1.18. Name Element
id / type: 0x536E / utf-8
path: \Segment\Tracks\TrackEntry\Name
maxOccurs: 1
definition: A human-readable track name.
5.1.4.1.19. Language Element
id / type / default: 0x22B59C / string / eng
path: \Segment\Tracks\TrackEntry\Language
minOccurs / maxOccurs: 1 / 1
definition: The language of the track in the Matroska languages
form; see Section 12 on language codes. This Element MUST be
ignored if the LanguageBCP47 Element is used in the same
TrackEntry.
5.1.4.1.20. LanguageBCP47 Element
id / type: 0x22B59D / string
path: \Segment\Tracks\TrackEntry\LanguageBCP47
maxOccurs: 1
minver: 4
definition: The language of the track in the [BCP47] form; see
Section 12 on language codes. If this Element is used, then any
Language Elements used in the same TrackEntry MUST be ignored.
5.1.4.1.21. CodecID Element
id / type: 0x86 / string
path: \Segment\Tracks\TrackEntry\CodecID
minOccurs / maxOccurs: 1 / 1
definition: An ID corresponding to the codec; see [MatroskaCodec]
for more info.
stream copy: True (Section 8)
5.1.4.1.22. CodecPrivate Element
id / type: 0x63A2 / binary
path: \Segment\Tracks\TrackEntry\CodecPrivate
maxOccurs: 1
definition: Private data only known to the codec.
stream copy: True (Section 8)
5.1.4.1.23. CodecName Element
id / type: 0x258688 / utf-8
path: \Segment\Tracks\TrackEntry\CodecName
maxOccurs: 1
definition: A human-readable string specifying the codec.
5.1.4.1.24. AttachmentLink Element
id / type: 0x7446 / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\AttachmentLink
maxOccurs: 1
maxver: 3
definition: The UID of an attachment that is used by this codec.
usage notes: The value MUST match the FileUID value of an attachment
found in this Segment.
5.1.4.1.25. CodecDelay Element
id / type / default: 0x56AA / uinteger / 0
path: \Segment\Tracks\TrackEntry\CodecDelay
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: The built-in delay for codec expressed in Matroska Ticks
-- i.e., in nanoseconds; see Section 11.1. It represents the
number of codec samples that will be discarded by the decoder
during playback. This timestamp value MUST be subtracted from
each frame timestamp in order to get the timestamp that will be
actually played. The value SHOULD be small so the muxing of
tracks with the same actual timestamp are in the same Cluster.
stream copy: True (Section 8)
5.1.4.1.26. SeekPreRoll Element
id / type / default: 0x56BB / uinteger / 0
path: \Segment\Tracks\TrackEntry\SeekPreRoll
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: After a discontinuity, SeekPreRoll is the duration of
the data that the decoder MUST decode before the decoded data is
valid and is expressed in Matroska Ticks -- i.e., in nanoseconds;
see Section 11.1.
stream copy: True (Section 8)
5.1.4.1.27. TrackTranslate Element
id / type: 0x6624 / master
path: \Segment\Tracks\TrackEntry\TrackTranslate
definition: The mapping between this TrackEntry and a track value in
the given Chapter Codec.
rationale: The Chapter Codec may need to address content in a
specific track, but they may not know of the way to identify
tracks in Matroska. This element and its child elements add a way
to map the internal tracks known to the Chapter Codec to the track
IDs in Matroska. This allows remuxing a file with Chapter Codec
without changing the content of the codec data and just the track
mapping.
5.1.4.1.27.1. TrackTranslateTrackID Element
id / type: 0x66A5 / binary
path: \Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateTrackI
D
minOccurs / maxOccurs: 1 / 1
definition: The binary value used to represent this TrackEntry in
the chapter codec data. The format depends on the
ChapProcessCodecID used; see Section 5.1.7.1.4.15.
5.1.4.1.27.2. TrackTranslateCodec Element
id / type: 0x66BF / uinteger
path: \Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateCodec
minOccurs / maxOccurs: 1 / 1
definition: This TrackTranslate applies to this chapter codec of the
given chapter edition(s); see Section 5.1.7.1.4.15.
defined values:
+=======+=================+============================+
| value | label | definition |
+=======+=================+============================+
| 0 | Matroska Script | Chapter commands using the |
| | | Matroska Script codec. |
+-------+-----------------+----------------------------+
| 1 | DVD-menu | Chapter commands using the |
| | | DVD-like codec. |
+-------+-----------------+----------------------------+
Table 4: TrackTranslateCodec Values
5.1.4.1.27.3. TrackTranslateEditionUID Element
id / type: 0x66FC / uinteger
path: \Segment\Tracks\TrackEntry\TrackTranslate\TrackTranslateEditio
nUID
definition: Specifies a chapter-edition UID in which this
TrackTranslate applies.
usage notes: When no TrackTranslateEditionUID is specified in the
TrackTranslate, the TrackTranslate applies to all chapter editions
found in the Segment using the given TrackTranslateCodec.
5.1.4.1.28. Video Element
id / type: 0xE0 / master
path: \Segment\Tracks\TrackEntry\Video
maxOccurs: 1
definition: Video settings.
5.1.4.1.28.1. FlagInterlaced Element
id / type / default: 0x9A / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\FlagInterlaced
minOccurs / maxOccurs: 1 / 1
minver: 2
definition: Specify whether the video frames in this track are
interlaced.
defined values:
+=======+==============+==========================+
| value | label | definition |
+=======+==============+==========================+
| 0 | undetermined | Unknown status. This |
| | | value SHOULD be avoided. |
+-------+--------------+--------------------------+
| 1 | interlaced | Interlaced frames. |
+-------+--------------+--------------------------+
| 2 | progressive | No interlacing. |
+-------+--------------+--------------------------+
Table 5: FlagInterlaced Values
stream copy: True (Section 8)
5.1.4.1.28.2. FieldOrder Element
id / type / default: 0x9D / uinteger / 2
path: \Segment\Tracks\TrackEntry\Video\FieldOrder
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: Specifies the field ordering of video frames in this
track.
defined values:
+=======+==============+=========================================+
| value | label | definition |
+=======+==============+=========================================+
| 0 | progressive | Interlaced frames. This value SHOULD |
| | | be avoided; setting FlagInterlaced to |
| | | 2 is sufficient. |
+-------+--------------+-----------------------------------------+
| 1 | tff | Top field displayed first. Top field |
| | | stored first. |
+-------+--------------+-----------------------------------------+
| 2 | undetermined | Unknown field order. This value |
| | | SHOULD be avoided. |
+-------+--------------+-----------------------------------------+
| 6 | bff | Bottom field displayed first. Bottom |
| | | field stored first. |
+-------+--------------+-----------------------------------------+
| 9 | bff(swapped) | Top field displayed first. Fields are |
| | | interleaved in storage with the top |
| | | line of the top field stored first. |
+-------+--------------+-----------------------------------------+
| 14 | tff(swapped) | Bottom field displayed first. Fields |
| | | are interleaved in storage with the |
| | | top line of the top field stored |
| | | first. |
+-------+--------------+-----------------------------------------+
Table 6: FieldOrder Values
usage notes: If FlagInterlaced is not set to 1, this Element MUST be
ignored.
stream copy: True (Section 8)
5.1.4.1.28.3. StereoMode Element
id / type / default: 0x53B8 / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\StereoMode
minOccurs / maxOccurs: 1 / 1
minver: 3
definition: Stereo-3D video mode; see Section 18.10 for more
details.
restrictions:
+=======+===================================================+
| value | label |
+=======+===================================================+
| 0 | mono |
+-------+---------------------------------------------------+
| 1 | side by side (left eye first) |
+-------+---------------------------------------------------+
| 2 | top - bottom (right eye is first) |
+-------+---------------------------------------------------+
| 3 | top - bottom (left eye is first) |
+-------+---------------------------------------------------+
| 4 | checkboard (right eye is first) |
+-------+---------------------------------------------------+
| 5 | checkboard (left eye is first) |
+-------+---------------------------------------------------+
| 6 | row interleaved (right eye is first) |
+-------+---------------------------------------------------+
| 7 | row interleaved (left eye is first) |
+-------+---------------------------------------------------+
| 8 | column interleaved (right eye is first) |
+-------+---------------------------------------------------+
| 9 | column interleaved (left eye is first) |
+-------+---------------------------------------------------+
| 10 | anaglyph (cyan/red) |
+-------+---------------------------------------------------+
| 11 | side by side (right eye first) |
+-------+---------------------------------------------------+
| 12 | anaglyph (green/magenta) |
+-------+---------------------------------------------------+
| 13 | both eyes laced in one Block (left eye is first) |
+-------+---------------------------------------------------+
| 14 | both eyes laced in one Block (right eye is first) |
+-------+---------------------------------------------------+
Table 7: StereoMode Values
stream copy: True (Section 8)
5.1.4.1.28.4. AlphaMode Element
id / type / default: 0x53C0 / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\AlphaMode
minOccurs / maxOccurs: 1 / 1
minver: 3
definition: Indicates whether the BlockAdditional Element with
BlockAddID of "1" contains Alpha data as defined by to the Codec
Mapping for the CodecID. Undefined values SHOULD NOT be used, as
the behavior of known implementations is different (considered
either as 0 or 1).
defined values:
+=======+=========+============================================+
| value | label | definition |
+=======+=========+============================================+
| 0 | none | The BlockAdditional Element with |
| | | BlockAddID of "1" does not exist or SHOULD |
| | | NOT be considered as containing such data. |
+-------+---------+--------------------------------------------+
| 1 | present | The BlockAdditional Element with |
| | | BlockAddID of "1" contains alpha channel |
| | | data. |
+-------+---------+--------------------------------------------+
Table 8: AlphaMode Values
stream copy: True (Section 8)
5.1.4.1.28.5. OldStereoMode Element
id / type: 0x53B9 / uinteger
path: \Segment\Tracks\TrackEntry\Video\OldStereoMode
maxOccurs: 1
maxver: 2
definition: Bogus StereoMode value used in old versions of
libmatroska.
restrictions:
+=======+===========+
| value | label |
+=======+===========+
| 0 | mono |
+-------+-----------+
| 1 | right eye |
+-------+-----------+
| 2 | left eye |
+-------+-----------+
| 3 | both eyes |
+-------+-----------+
Table 9: OldStereoMode
Values
usage notes: This Element MUST NOT be used. It was an incorrect
value used in libmatroska up to 0.9.0.
5.1.4.1.28.6. PixelWidth Element
id / type: 0xB0 / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\Video\PixelWidth
minOccurs / maxOccurs: 1 / 1
definition: Width of the encoded video frames in pixels.
stream copy: True (Section 8)
5.1.4.1.28.7. PixelHeight Element
id / type: 0xBA / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\Video\PixelHeight
minOccurs / maxOccurs: 1 / 1
definition: Height of the encoded video frames in pixels.
stream copy: True (Section 8)
5.1.4.1.28.8. PixelCropBottom Element
id / type / default: 0x54AA / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\PixelCropBottom
minOccurs / maxOccurs: 1 / 1
definition: The number of video pixels to remove at the bottom of
the image.
stream copy: True (Section 8)
5.1.4.1.28.9. PixelCropTop Element
id / type / default: 0x54BB / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\PixelCropTop
minOccurs / maxOccurs: 1 / 1
definition: The number of video pixels to remove at the top of the
image.
stream copy: True (Section 8)
5.1.4.1.28.10. PixelCropLeft Element
id / type / default: 0x54CC / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\PixelCropLeft
minOccurs / maxOccurs: 1 / 1
definition: The number of video pixels to remove on the left of the
image.
stream copy: True (Section 8)
5.1.4.1.28.11. PixelCropRight Element
id / type / default: 0x54DD / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\PixelCropRight
minOccurs / maxOccurs: 1 / 1
definition: The number of video pixels to remove on the right of the
image.
stream copy: True (Section 8)
5.1.4.1.28.12. DisplayWidth Element
id / type: 0x54B0 / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\Video\DisplayWidth
maxOccurs: 1
definition: Width of the video frames to display. Applies to the
video frame after cropping (PixelCrop* Elements).
notes:
+===========+==================================================+
| attribute | note |
+===========+==================================================+
| default | If the DisplayUnit of the same TrackEntry is 0, |
| | then the default value for DisplayWidth is equal |
| | to PixelWidth - PixelCropLeft - PixelCropRight; |
| | otherwise, there is no default value. |
+-----------+--------------------------------------------------+
Table 10: DisplayWidth Implementation Notes
stream copy: True (Section 8)
5.1.4.1.28.13. DisplayHeight Element
id / type: 0x54BA / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\Video\DisplayHeight
maxOccurs: 1
definition: Height of the video frames to display. Applies to the
video frame after cropping (PixelCrop* Elements).
notes:
+===========+===================================================+
| attribute | note |
+===========+===================================================+
| default | If the DisplayUnit of the same TrackEntry is 0, |
| | then the default value for DisplayHeight is equal |
| | to PixelHeight - PixelCropTop - PixelCropBottom; |
| | otheriwse, there is no default value. |
+-----------+---------------------------------------------------+
Table 11: DisplayHeight Implementation Notes
stream copy: True (Section 8)
5.1.4.1.28.14. DisplayUnit Element
id / type / default: 0x54B2 / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\DisplayUnit
minOccurs / maxOccurs: 1 / 1
definition: How DisplayWidth and DisplayHeight are interpreted.
restrictions:
+=======+======================+
| value | label |
+=======+======================+
| 0 | pixels |
+-------+----------------------+
| 1 | centimeters |
+-------+----------------------+
| 2 | inches |
+-------+----------------------+
| 3 | display aspect ratio |
+-------+----------------------+
| 4 | unknown |
+-------+----------------------+
Table 12: DisplayUnit Values
5.1.4.1.28.15. UncompressedFourCC Element
id / type: 0x2EB524 / binary
length: 4
path: \Segment\Tracks\TrackEntry\Video\UncompressedFourCC
minOccurs / maxOccurs: see implementation notes / 1
definition: Specifies the uncompressed pixel format used for the
Track's data as a FourCC. This value is similar in scope to the
biCompression value of AVI's BITMAPINFO [AVIFormat]. There is
neither a definitive list of FourCC values nor an official
registry. Some common values for YUV pixel formats can be found
at [MSYUV8], [MSYUV16], and [FourCC-YUV]. Some common values for
uncompressed RGB pixel formats can be found at [MSRGB] and
[FourCC-RGB].
notes:
+===========+===============================================+
| attribute | note |
+===========+===============================================+
| minOccurs | UncompressedFourCC MUST be set (minOccurs=1) |
| | in the TrackEntry when the CodecID Element of |
| | the TrackEntry is set to "V_UNCOMPRESSED". |
+-----------+-----------------------------------------------+
Table 13: UncompressedFourCC Implementation Notes
stream copy: True (Section 8)
5.1.4.1.28.16. Colour Element
id / type: 0x55B0 / master
path: \Segment\Tracks\TrackEntry\Video\Colour
maxOccurs: 1
minver: 4
definition: Settings describing the colour format.
stream copy: True (Section 8)
5.1.4.1.28.17. MatrixCoefficients Element
id / type / default: 0x55B1 / uinteger / 2
path: \Segment\Tracks\TrackEntry\Video\Colour\MatrixCoefficients
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: The Matrix Coefficients of the video used to derive luma
and chroma values from red, green, and blue color primaries. For
clarity, the value and meanings for MatrixCoefficients are adopted
from Table 4 of [ITU-H.273].
restrictions:
+=======+=======================================+
| value | label |
+=======+=======================================+
| 0 | Identity |
+-------+---------------------------------------+
| 1 | ITU-R BT.709 |
+-------+---------------------------------------+
| 2 | unspecified |
+-------+---------------------------------------+
| 3 | reserved |
+-------+---------------------------------------+
| 4 | US FCC 73.682 |
+-------+---------------------------------------+
| 5 | ITU-R BT.470BG |
+-------+---------------------------------------+
| 6 | SMPTE 170M |
+-------+---------------------------------------+
| 7 | SMPTE 240M |
+-------+---------------------------------------+
| 8 | YCoCg |
+-------+---------------------------------------+
| 9 | BT2020 Non-constant Luminance |
+-------+---------------------------------------+
| 10 | BT2020 Constant Luminance |
+-------+---------------------------------------+
| 11 | SMPTE ST 2085 |
+-------+---------------------------------------+
| 12 | Chroma-derived Non-constant Luminance |
+-------+---------------------------------------+
| 13 | Chroma-derived Constant Luminance |
+-------+---------------------------------------+
| 14 | ITU-R BT.2100-0 |
+-------+---------------------------------------+
Table 14: MatrixCoefficients Values
stream copy: True (Section 8)
5.1.4.1.28.18. BitsPerChannel Element
id / type / default: 0x55B2 / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\Colour\BitsPerChannel
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: Number of decoded bits per channel. A value of 0
indicates that the BitsPerChannel is unspecified.
stream copy: True (Section 8)
5.1.4.1.28.19. ChromaSubsamplingHorz Element
id / type: 0x55B3 / uinteger
path: \Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingHorz
maxOccurs: 1
minver: 4
definition: The amount of pixels to remove in the Cr and Cb channels
for every pixel not removed horizontally. For example, the
ChromaSubsamplingHorz SHOULD be set to 1 for a video with 4:2:0
chroma subsampling.
stream copy: True (Section 8)
5.1.4.1.28.20. ChromaSubsamplingVert Element
id / type: 0x55B4 / uinteger
path: \Segment\Tracks\TrackEntry\Video\Colour\ChromaSubsamplingVert
maxOccurs: 1
minver: 4
definition: The amount of pixels to remove in the Cr and Cb channels
for every pixel not removed vertically. For example, the
ChromaSubsamplingVert SHOULD be set to 1 for a video with 4:2:0
chroma subsampling.
stream copy: True (Section 8)
5.1.4.1.28.21. CbSubsamplingHorz Element
id / type: 0x55B5 / uinteger
path: \Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingHorz
maxOccurs: 1
minver: 4
definition: The amount of pixels to remove in the Cb channel for
every pixel not removed horizontally. This is additive with
ChromaSubsamplingHorz. For example, the ChromaSubsamplingHorz and
CbSubsamplingHorz SHOULD be set to 1 for a video with 4:2:1 chroma
subsampling.
stream copy: True (Section 8)
5.1.4.1.28.22. CbSubsamplingVert Element
id / type: 0x55B6 / uinteger
path: \Segment\Tracks\TrackEntry\Video\Colour\CbSubsamplingVert
maxOccurs: 1
minver: 4
definition: The amount of pixels to remove in the Cb channel for
every pixel not removed vertically. This is additive with
ChromaSubsamplingVert.
stream copy: True (Section 8)
5.1.4.1.28.23. ChromaSitingHorz Element
id / type / default: 0x55B7 / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingHorz
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: How chroma is subsampled horizontally.
restrictions:
+=======+=================+
| value | label |
+=======+=================+
| 0 | unspecified |
+-------+-----------------+
| 1 | left collocated |
+-------+-----------------+
| 2 | half |
+-------+-----------------+
Table 15:
ChromaSitingHorz Values
stream copy: True (Section 8)
5.1.4.1.28.24. ChromaSitingVert Element
id / type / default: 0x55B8 / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\Colour\ChromaSitingVert
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: How chroma is subsampled vertically.
restrictions:
+=======+================+
| value | label |
+=======+================+
| 0 | unspecified |
+-------+----------------+
| 1 | top collocated |
+-------+----------------+
| 2 | half |
+-------+----------------+
Table 16:
ChromaSitingVert
Values
stream copy: True (Section 8)
5.1.4.1.28.25. Range Element
id / type / default: 0x55B9 / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\Colour\Range
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: Clipping of the color ranges.
restrictions:
+=======+===============================+
| value | label |
+=======+===============================+
| 0 | unspecified |
+-------+-------------------------------+
| 1 | broadcast range |
+-------+-------------------------------+
| 2 | full range (no clipping) |
+-------+-------------------------------+
| 3 | defined by MatrixCoefficients |
| | / TransferCharacteristics |
+-------+-------------------------------+
Table 17: Range Values
stream copy: True (Section 8)
5.1.4.1.28.26. TransferCharacteristics Element
id / type / default: 0x55BA / uinteger / 2
path: \Segment\Tracks\TrackEntry\Video\Colour\TransferCharacteristic
s
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: The transfer characteristics of the video. For clarity,
the value and meanings for TransferCharacteristics are adopted
from Table 3 of [ITU-H.273].
restrictions:
+=======+=======================================+
| value | label |
+=======+=======================================+
| 0 | reserved |
+-------+---------------------------------------+
| 1 | ITU-R BT.709 |
+-------+---------------------------------------+
| 2 | unspecified |
+-------+---------------------------------------+
| 3 | reserved2 |
+-------+---------------------------------------+
| 4 | Gamma 2.2 curve - BT.470M |
+-------+---------------------------------------+
| 5 | Gamma 2.8 curve - BT.470BG |
+-------+---------------------------------------+
| 6 | SMPTE 170M |
+-------+---------------------------------------+
| 7 | SMPTE 240M |
+-------+---------------------------------------+
| 8 | Linear |
+-------+---------------------------------------+
| 9 | Log |
+-------+---------------------------------------+
| 10 | Log Sqrt |
+-------+---------------------------------------+
| 11 | IEC 61966-2-4 |
+-------+---------------------------------------+
| 12 | ITU-R BT.1361 Extended Colour Gamut |
+-------+---------------------------------------+
| 13 | IEC 61966-2-1 |
+-------+---------------------------------------+
| 14 | ITU-R BT.2020 10 bit |
+-------+---------------------------------------+
| 15 | ITU-R BT.2020 12 bit |
+-------+---------------------------------------+
| 16 | ITU-R BT.2100 Perceptual Quantization |
+-------+---------------------------------------+
| 17 | SMPTE ST 428-1 |
+-------+---------------------------------------+
| 18 | ARIB STD-B67 (HLG) |
+-------+---------------------------------------+
Table 18: TransferCharacteristics Values
stream copy: True (Section 8)
5.1.4.1.28.27. Primaries Element
id / type / default: 0x55BB / uinteger / 2
path: \Segment\Tracks\TrackEntry\Video\Colour\Primaries
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: The colour primaries of the video. For clarity, the
value and meanings for Primaries are adopted from Table 2 of
[ITU-H.273].
restrictions:
+=======+========================================+
| value | label |
+=======+========================================+
| 0 | reserved |
+-------+----------------------------------------+
| 1 | ITU-R BT.709 |
+-------+----------------------------------------+
| 2 | unspecified |
+-------+----------------------------------------+
| 3 | reserved2 |
+-------+----------------------------------------+
| 4 | ITU-R BT.470M |
+-------+----------------------------------------+
| 5 | ITU-R BT.470BG - BT.601 625 |
+-------+----------------------------------------+
| 6 | ITU-R BT.601 525 - SMPTE 170M |
+-------+----------------------------------------+
| 7 | SMPTE 240M |
+-------+----------------------------------------+
| 8 | FILM |
+-------+----------------------------------------+
| 9 | ITU-R BT.2020 |
+-------+----------------------------------------+
| 10 | SMPTE ST 428-1 |
+-------+----------------------------------------+
| 11 | SMPTE RP 432-2 |
+-------+----------------------------------------+
| 12 | SMPTE EG 432-2 |
+-------+----------------------------------------+
| 22 | EBU Tech. 3213-E - JEDEC P22 phosphors |
+-------+----------------------------------------+
Table 19: Primaries Values
stream copy: True (Section 8)
5.1.4.1.28.28. MaxCLL Element
id / type: 0x55BC / uinteger
path: \Segment\Tracks\TrackEntry\Video\Colour\MaxCLL
maxOccurs: 1
minver: 4
definition: Maximum brightness of a single pixel (Maximum Content
Light Level) in candelas per square meter (cd/m^2).
stream copy: True (Section 8)
5.1.4.1.28.29. MaxFALL Element
id / type: 0x55BD / uinteger
path: \Segment\Tracks\TrackEntry\Video\Colour\MaxFALL
maxOccurs: 1
minver: 4
definition: Maximum brightness of a single full frame (Maximum
Frame-Average Light Level) in candelas per square meter (cd/m^2).
stream copy: True (Section 8)
5.1.4.1.28.30. MasteringMetadata Element
id / type: 0x55D0 / master
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata
maxOccurs: 1
minver: 4
definition: SMPTE 2086 mastering data.
stream copy: True (Section 8)
5.1.4.1.28.31. PrimaryRChromaticityX Element
id / type: 0x55D1 / float
range: 0x0p+0-0x1p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim
aryRChromaticityX
maxOccurs: 1
minver: 4
definition: Red X chromaticity coordinate as defined by [CIE-1931].
stream copy: True (Section 8)
5.1.4.1.28.32. PrimaryRChromaticityY Element
id / type: 0x55D2 / float
range: 0x0p+0-0x1p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim
aryRChromaticityY
maxOccurs: 1
minver: 4
definition: Red Y chromaticity coordinate as defined by [CIE-1931].
stream copy: True (Section 8)
5.1.4.1.28.33. PrimaryGChromaticityX Element
id / type: 0x55D3 / float
range: 0x0p+0-0x1p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim
aryGChromaticityX
maxOccurs: 1
minver: 4
definition: Green X chromaticity coordinate as defined by
[CIE-1931].
stream copy: True (Section 8)
5.1.4.1.28.34. PrimaryGChromaticityY Element
id / type: 0x55D4 / float
range: 0x0p+0-0x1p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim
aryGChromaticityY
maxOccurs: 1
minver: 4
definition: Green Y chromaticity coordinate as defined by
[CIE-1931].
stream copy: True (Section 8)
5.1.4.1.28.35. PrimaryBChromaticityX Element
id / type: 0x55D5 / float
range: 0x0p+0-0x1p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim
aryBChromaticityX
maxOccurs: 1
minver: 4
definition: Blue X chromaticity coordinate as defined by [CIE-1931].
stream copy: True (Section 8)
5.1.4.1.28.36. PrimaryBChromaticityY Element
id / type: 0x55D6 / float
range: 0x0p+0-0x1p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Prim
aryBChromaticityY
maxOccurs: 1
minver: 4
definition: Blue Y chromaticity coordinate as defined by [CIE-1931].
stream copy: True (Section 8)
5.1.4.1.28.37. WhitePointChromaticityX Element
id / type: 0x55D7 / float
range: 0x0p+0-0x1p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Whit
ePointChromaticityX
maxOccurs: 1
minver: 4
definition: White X chromaticity coordinate as defined by
[CIE-1931].
stream copy: True (Section 8)
5.1.4.1.28.38. WhitePointChromaticityY Element
id / type: 0x55D8 / float
range: 0x0p+0-0x1p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Whit
ePointChromaticityY
maxOccurs: 1
minver: 4
definition: White Y chromaticity coordinate as defined by
[CIE-1931].
stream copy: True (Section 8)
5.1.4.1.28.39. LuminanceMax Element
id / type: 0x55D9 / float
range: >= 0x0p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Lumi
nanceMax
maxOccurs: 1
minver: 4
definition: Maximum luminance. Represented in candelas per square
meter (cd/m^2).
stream copy: True (Section 8)
5.1.4.1.28.40. LuminanceMin Element
id / type: 0x55DA / float
range: >= 0x0p+0
path: \Segment\Tracks\TrackEntry\Video\Colour\MasteringMetadata\Lumi
nanceMin
maxOccurs: 1
minver: 4
definition: Minimum luminance. Represented in candelas per square
meter (cd/m^2).
stream copy: True (Section 8)
5.1.4.1.28.41. Projection Element
id / type: 0x7670 / master
path: \Segment\Tracks\TrackEntry\Video\Projection
maxOccurs: 1
minver: 4
definition: Describes the video projection details. Used to render
spherical, VR videos or flipping videos horizontally/vertically.
stream copy: True (Section 8)
5.1.4.1.28.42. ProjectionType Element
id / type / default: 0x7671 / uinteger / 0
path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionType
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: Describes the projection used for this video track.
restrictions:
+=======+=================+
| value | label |
+=======+=================+
| 0 | rectangular |
+-------+-----------------+
| 1 | equirectangular |
+-------+-----------------+
| 2 | cubemap |
+-------+-----------------+
| 3 | mesh |
+-------+-----------------+
Table 20:
ProjectionType Values
stream copy: True (Section 8)
5.1.4.1.28.43. ProjectionPrivate Element
id / type: 0x7672 / binary
path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionPrivate
maxOccurs: 1
minver: 4
definition: Private data that only applies to a specific projection.
* If ProjectionType equals 0 (rectangular), then this element
MUST NOT be present.
* If ProjectionType equals 1 (equirectangular), then this element
MUST be present and contain the same binary data that would be
stored inside an ISOBMFF Equirectangular Projection Box
("equi").
* If ProjectionType equals 2 (cubemap), then this element MUST be
present and contain the same binary data that would be stored
inside an ISOBMFF Cubemap Projection Box ("cbmp").
* If ProjectionType equals 3 (mesh), then this element MUST be
present and contain the same binary data that would be stored
inside an ISOBMFF Mesh Projection Box ("mshp").
usage notes: ISOBMFF box size and FourCC fields are not included in
the binary data, but the FullBox version and flag fields are.
This is to avoid redundant framing information while preserving
versioning and semantics between the two container formats.
stream copy: True (Section 8)
5.1.4.1.28.44. ProjectionPoseYaw Element
id / type / default: 0x7673 / float / 0x0p+0
range: >= -0xB4p+0, <= 0xB4p+0
path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseYaw
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: Specifies a yaw rotation to the projection.
stream copy: True (Section 8)
Value represents a clockwise rotation, in degrees, around the up
vector. This rotation must be applied before any ProjectionPosePitch
or ProjectionPoseRoll rotations. The value of this element MUST be
in the -180 to 180 degree range, both included.
Setting ProjectionPoseYaw to -180 or 180 degrees with the
ProjectionPoseRoll and ProjectionPosePitch set to 0 degrees flips the
image horizontally.
5.1.4.1.28.45. ProjectionPosePitch Element
id / type / default: 0x7674 / float / 0x0p+0
range: >= -0x5Ap+0, <= 0x5Ap+0
path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionPosePitc
h
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: Specifies a pitch rotation to the projection.
stream copy: True (Section 8)
Value represents a counter-clockwise rotation, in degrees, around the
right vector. This rotation must be applied after the
ProjectionPoseYaw rotation and before the ProjectionPoseRoll
rotation. The value of this element MUST be in the -90 to 90 degree
range, both included.
5.1.4.1.28.46. ProjectionPoseRoll Element
id / type / default: 0x7675 / float / 0x0p+0
range: >= -0xB4p+0, <= 0xB4p+0
path: \Segment\Tracks\TrackEntry\Video\Projection\ProjectionPoseRoll
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: Specifies a roll rotation to the projection.
stream copy: True (Section 8)
Value represents a counter-clockwise rotation, in degrees, around the
forward vector. This rotation must be applied after the
ProjectionPoseYaw and ProjectionPosePitch rotations. The value of
this element MUST be in the -180 to 180 degree range, both included.
Setting ProjectionPoseRoll to -180 or 180 degrees and
ProjectionPoseYaw to 180 or -180 degrees with ProjectionPosePitch set
to 0 degrees flips the image vertically.
Setting ProjectionPoseRoll to 180 or -180 degrees with
ProjectionPoseYaw and ProjectionPosePitch set to 0 degrees flips the
image horizontally and vertically.
5.1.4.1.29. Audio Element
id / type: 0xE1 / master
path: \Segment\Tracks\TrackEntry\Audio
maxOccurs: 1
definition: Audio settings.
5.1.4.1.29.1. SamplingFrequency Element
id / type / default: 0xB5 / float / 0x1.f4p+12
range: > 0x0p+0
path: \Segment\Tracks\TrackEntry\Audio\SamplingFrequency
minOccurs / maxOccurs: 1 / 1
definition: Sampling frequency in Hz.
stream copy: True (Section 8)
5.1.4.1.29.2. OutputSamplingFrequency Element
id / type: 0x78B5 / float
range: > 0x0p+0
path: \Segment\Tracks\TrackEntry\Audio\OutputSamplingFrequency
maxOccurs: 1
definition: Real output sampling frequency in Hz (used for SBR
techniques).
notes:
+===========+===============================================+
| attribute | note |
+===========+===============================================+
| default | The default value for OutputSamplingFrequency |
| | of the same TrackEntry is equal to the |
| | SamplingFrequency. |
+-----------+-----------------------------------------------+
Table 21: OutputSamplingFrequency Implementation Notes
5.1.4.1.29.3. Channels Element
id / type / default: 0x9F / uinteger / 1
range: not 0
path: \Segment\Tracks\TrackEntry\Audio\Channels
minOccurs / maxOccurs: 1 / 1
definition: Numbers of channels in the track.
stream copy: True (Section 8)
5.1.4.1.29.4. BitDepth Element
id / type: 0x6264 / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\Audio\BitDepth
maxOccurs: 1
definition: Bits per sample. Mostly used for PCM.
stream copy: True (Section 8)
5.1.4.1.30. TrackOperation Element
id / type: 0xE2 / master
path: \Segment\Tracks\TrackEntry\TrackOperation
maxOccurs: 1
minver: 3
definition: Operation that needs to be applied on tracks to create
this virtual track; see Section 18.8 for more details.
stream copy: True (Section 8)
5.1.4.1.30.1. TrackCombinePlanes Element
id / type: 0xE3 / master
path: \Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes
maxOccurs: 1
minver: 3
definition: Contains the list of all video plane tracks that need to
be combined to create this 3D track.
stream copy: True (Section 8)
5.1.4.1.30.2. TrackPlane Element
id / type: 0xE4 / master
path: \Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\T
rackPlane
minOccurs: 1
minver: 3
definition: Contains a video plane track that needs to be combined
to create this 3D track.
stream copy: True (Section 8)
5.1.4.1.30.3. TrackPlaneUID Element
id / type: 0xE5 / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\T
rackPlane\TrackPlaneUID
minOccurs / maxOccurs: 1 / 1
minver: 3
definition: The trackUID number of the track representing the plane.
stream copy: True (Section 8)
5.1.4.1.30.4. TrackPlaneType Element
id / type: 0xE6 / uinteger
path: \Segment\Tracks\TrackEntry\TrackOperation\TrackCombinePlanes\T
rackPlane\TrackPlaneType
minOccurs / maxOccurs: 1 / 1
minver: 3
definition: The kind of plane this track corresponds to.
restrictions:
+=======+============+
| value | label |
+=======+============+
| 0 | left eye |
+-------+------------+
| 1 | right eye |
+-------+------------+
| 2 | background |
+-------+------------+
Table 22:
TrackPlaneType Values
stream copy: True (Section 8)
5.1.4.1.30.5. TrackJoinBlocks Element
id / type: 0xE9 / master
path: \Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks
maxOccurs: 1
minver: 3
definition: Contains the list of all tracks whose Blocks need to be
combined to create this virtual track.
stream copy: True (Section 8)
5.1.4.1.30.6. TrackJoinUID Element
id / type: 0xED / uinteger
range: not 0
path: \Segment\Tracks\TrackEntry\TrackOperation\TrackJoinBlocks\Trac
kJoinUID
minOccurs: 1
minver: 3
definition: The trackUID number of a track whose blocks are used to
create this virtual track.
stream copy: True (Section 8)
5.1.4.1.31. ContentEncodings Element
id / type: 0x6D80 / master
path: \Segment\Tracks\TrackEntry\ContentEncodings
maxOccurs: 1
definition: Settings for several content encoding mechanisms like
compression or encryption.
stream copy: True (Section 8)
5.1.4.1.31.1. ContentEncoding Element
id / type: 0x6240 / master
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding
minOccurs: 1
definition: Settings for one content encoding like compression or
encryption.
stream copy: True (Section 8)
5.1.4.1.31.2. ContentEncodingOrder Element
id / type / default: 0x5031 / uinteger / 0
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncodingOrder
minOccurs / maxOccurs: 1 / 1
definition: Tell in which order to apply each ContentEncoding of the
ContentEncodings. The decoder/demuxer MUST start with the
ContentEncoding with the highest ContentEncodingOrder and work its
way down to the ContentEncoding with the lowest
ContentEncodingOrder. This value MUST be unique over for each
ContentEncoding found in the ContentEncodings of this TrackEntry.
stream copy: True (Section 8)
5.1.4.1.31.3. ContentEncodingScope Element
id / type / default: 0x5032 / uinteger / 1
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncodingScope
minOccurs / maxOccurs: 1 / 1
definition: A bit field that describes which Elements have been
modified in this way. Values (big-endian) can be OR'ed.
defined values:
+=======+=========+============================================+
| value | label | definition |
+=======+=========+============================================+
| 1 | Block | All frame contents excluding lacing data. |
+-------+---------+--------------------------------------------+
| 2 | Private | The track's CodecPrivate data. |
+-------+---------+--------------------------------------------+
| 4 | Next | The next ContentEncoding (next |
| | | ContentEncodingOrder; either the data |
| | | inside ContentCompression and/or |
| | | ContentEncryption). This value SHOULD NOT |
| | | be used, as it's not supported by players. |
+-------+---------+--------------------------------------------+
Table 23: ContentEncodingScope Values
stream copy: True (Section 8)
5.1.4.1.31.4. ContentEncodingType Element
id / type / default: 0x5033 / uinteger / 0
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncodingType
minOccurs / maxOccurs: 1 / 1
definition: A value describing the kind of transformation that is
applied.
restrictions:
+=======+=============+
| value | label |
+=======+=============+
| 0 | Compression |
+-------+-------------+
| 1 | Encryption |
+-------+-------------+
Table 24:
ContentEncodingType
Values
stream copy: True (Section 8)
5.1.4.1.31.5. ContentCompression Element
id / type: 0x5034 / master
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentCompression
maxOccurs: 1
definition: Settings describing the compression used. This Element
MUST be present if the value of ContentEncodingType is 0 and
absent otherwise. Each block MUST be decompressable, even if no
previous block is available in order to not prevent seeking.
stream copy: True (Section 8)
5.1.4.1.31.6. ContentCompAlgo Element
id / type / default: 0x4254 / uinteger / 0
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentCompression\ContentCompAlgo
minOccurs / maxOccurs: 1 / 1
definition: The compression algorithm used.
defined values:
+=======+===========+=========================================+
| value | label | definition |
+=======+===========+=========================================+
| 0 | zlib | zlib compression [RFC1950] |
+-------+-----------+-----------------------------------------+
| 1 | bzlib | bzip2 compression [BZIP2], SHOULD NOT |
| | | be used; see usage notes. |
+-------+-----------+-----------------------------------------+
| 2 | lzo1x | Lempel-Ziv-Oberhumer compression [LZO], |
| | | SHOULD NOT be used; see usage notes. |
+-------+-----------+-----------------------------------------+
| 3 | Header | Octets in ContentCompSettings |
| | Stripping | (Section 5.1.4.1.31.7) have been |
| | | stripped from each frame. |
+-------+-----------+-----------------------------------------+
Table 25: ContentCompAlgo Values
usage notes: Compression method "1" (bzlib) and "2" (lzo1x) are
lacking proper documentation on the format, which limits
implementation possibilities. Due to licensing conflicts on
commonly available libraries compression methods, "2" (lzo1x) does
not offer widespread interoperability. A Matroska Writer SHOULD
NOT use these compression methods by default. A Matroska Reader
MAY support methods "1" and "2" if possible and SHOULD support
other methods.
stream copy: True (Section 8)
5.1.4.1.31.7. ContentCompSettings Element
id / type: 0x4255 / binary
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentCompression\ContentCompSettings
maxOccurs: 1
definition: Settings that might be needed by the decompressor. For
Header Stripping (ContentCompAlgo=3), the bytes that were removed
from the beginning of each frames of the track.
stream copy: True (Section 8)
5.1.4.1.31.8. ContentEncryption Element
id / type: 0x5035 / master
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption
maxOccurs: 1
definition: Settings describing the encryption used. This Element
MUST be present if the value of ContentEncodingType is 1
(encryption) and MUST be ignored otherwise. A Matroska Player MAY
support encryption.
stream copy: True (Section 8)
5.1.4.1.31.9. ContentEncAlgo Element
id / type / default: 0x47E1 / uinteger / 0
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentEncAlgo
minOccurs / maxOccurs: 1 / 1
definition: The encryption algorithm used.
defined values:
+=======+===========+============================================+
| value | label | definition |
+=======+===========+============================================+
| 0 | Not | The data is not encrypted. |
| | encrypted | |
+-------+-----------+--------------------------------------------+
| 1 | DES | Data Encryption Standard |
| | | (DES) [FIPS46-3]. This |
| | | value SHOULD be avoided. |
+-------+-----------+--------------------------------------------+
| 2 | 3DES | Triple Data Encryption |
| | | Algorithm [SP800-67]. This |
| | | value SHOULD be avoided. |
+-------+-----------+--------------------------------------------+
| 3 | Twofish | Twofish Encryption |
| | | Algorithm [Twofish]. |
+-------+-----------+--------------------------------------------+
| 4 | Blowfish | Blowfish Encryption |
| | | Algorithm [Blowfish]. This |
| | | value SHOULD be avoided. |
+-------+-----------+--------------------------------------------+
| 5 | AES | Advanced Encryption |
| | | Standard (AES) [FIPS197]. |
+-------+-----------+--------------------------------------------+
Table 26: ContentEncAlgo Values
stream copy: True (Section 8)
5.1.4.1.31.10. ContentEncKeyID Element
id / type: 0x47E2 / binary
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentEncKeyID
maxOccurs: 1
definition: The ID of the public key that the data was encrypted
with for public key algorithms.
stream copy: True (Section 8)
5.1.4.1.31.11. ContentEncAESSettings Element
id / type: 0x47E7 / master
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentEncAESSettings
maxOccurs: 1
minver: 4
definition: Settings describing the encryption algorithm used.
notes:
+===========+=================================================+
| attribute | note |
+===========+=================================================+
| maxOccurs | ContentEncAESSettings MUST NOT be set |
| | (maxOccurs=0) if ContentEncAlgo is not AES (5). |
+-----------+-------------------------------------------------+
Table 27: ContentEncAESSettings Implementation Notes
stream copy: True (Section 8)
5.1.4.1.31.12. AESSettingsCipherMode Element
id / type: 0x47E8 / uinteger
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentEncAESSettings\AESSettingsCipherMode
minOccurs / maxOccurs: 1 / 1
minver: 4
definition: The AES cipher mode used in the encryption.
defined values:
+=======+=========+====================================+
| value | label | definition |
+=======+=========+====================================+
| 1 | AES-CTR | Counter [SP800-38A]. |
+-------+---------+------------------------------------+
| 2 | AES-CBC | Cipher Block Chaining [SP800-38A]. |
+-------+---------+------------------------------------+
Table 28: AESSettingsCipherMode Values
notes:
+===========+=================================================+
| attribute | note |
+===========+=================================================+
| maxOccurs | AESSettingsCipherMode MUST NOT be set |
| | (maxOccurs=0) if ContentEncAlgo is not AES (5). |
+-----------+-------------------------------------------------+
Table 29: AESSettingsCipherMode Implementation Notes
stream copy: True (Section 8)
5.1.5. Cues Element
id / type: 0x1C53BB6B / master
path: \Segment\Cues
minOccurs / maxOccurs: see implementation notes / 1
definition: A Top-Level Element to speed seeking access. All
entries are local to the Segment.
notes:
+===========+====================================================+
| attribute | note |
+===========+====================================================+
| minOccurs | This Element SHOULD be set when |
| | the Segment is not transmitted as |
| | a live stream; see Section 23.2. |
+-----------+----------------------------------------------------+
Table 30: Cues Implementation Notes
5.1.5.1. CuePoint Element
id / type: 0xBB / master
path: \Segment\Cues\CuePoint
minOccurs: 1
definition: Contains all information relative to a seek point in the
Segment.
5.1.5.1.1. CueTime Element
id / type: 0xB3 / uinteger
path: \Segment\Cues\CuePoint\CueTime
minOccurs / maxOccurs: 1 / 1
definition: Absolute timestamp of the seek point expressed in
Matroska Ticks -- i.e., in nanoseconds; see Section 11.1.
5.1.5.1.2. CueTrackPositions Element
id / type: 0xB7 / master
path: \Segment\Cues\CuePoint\CueTrackPositions
minOccurs: 1
definition: Contains positions for different tracks corresponding to
the timestamp.
5.1.5.1.2.1. CueTrack Element
id / type: 0xF7 / uinteger
range: not 0
path: \Segment\Cues\CuePoint\CueTrackPositions\CueTrack
minOccurs / maxOccurs: 1 / 1
definition: The track for which a position is given.
5.1.5.1.2.2. CueClusterPosition Element
id / type: 0xF1 / uinteger
path: \Segment\Cues\CuePoint\CueTrackPositions\CueClusterPosition
minOccurs / maxOccurs: 1 / 1
definition: The Segment Position (Section 16) of the Cluster
containing the associated Block.
5.1.5.1.2.3. CueRelativePosition Element
id / type: 0xF0 / uinteger
path: \Segment\Cues\CuePoint\CueTrackPositions\CueRelativePosition
maxOccurs: 1
minver: 4
definition: The relative position inside the Cluster of the
referenced SimpleBlock or BlockGroup with 0 being the first
possible position for an Element inside that Cluster.
5.1.5.1.2.4. CueDuration Element
id / type: 0xB2 / uinteger
path: \Segment\Cues\CuePoint\CueTrackPositions\CueDuration
maxOccurs: 1
minver: 4
definition: The duration of the block expressed in Segment Ticks,
which are based on TimestampScale; see Section 11.1. If this
element is missing, the track's DefaultDuration does not apply and
no duration information is available in terms of the cues.
5.1.5.1.2.5. CueBlockNumber Element
id / type: 0x5378 / uinteger
range: not 0
path: \Segment\Cues\CuePoint\CueTrackPositions\CueBlockNumber
maxOccurs: 1
definition: Number of the Block in the specified Cluster.
5.1.5.1.2.6. CueCodecState Element
id / type / default: 0xEA / uinteger / 0
path: \Segment\Cues\CuePoint\CueTrackPositions\CueCodecState
minOccurs / maxOccurs: 1 / 1
minver: 2
definition: The Segment Position (Section 16) of the Codec State
corresponding to this Cue Element. 0 means that the data is taken
from the initial Track Entry.
5.1.5.1.2.7. CueReference Element
id / type: 0xDB / master
path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference
minver: 2
definition: The Clusters containing the referenced Blocks.
5.1.5.1.2.8. CueRefTime Element
id / type: 0x96 / uinteger
path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefTi
me
minOccurs / maxOccurs: 1 / 1
minver: 2
definition: Timestamp of the referenced Block expressed in Matroska
Ticks -- i.e., in nanoseconds; see Section 11.1.
5.1.6. Attachments Element
id / type: 0x1941A469 / master
path: \Segment\Attachments
maxOccurs: 1
definition: Contains attached files.
5.1.6.1. AttachedFile Element
id / type: 0x61A7 / master
path: \Segment\Attachments\AttachedFile
minOccurs: 1
definition: An attached file.
5.1.6.1.1. FileDescription Element
id / type: 0x467E / utf-8
path: \Segment\Attachments\AttachedFile\FileDescription
maxOccurs: 1
definition: A human-friendly name for the attached file.
5.1.6.1.2. FileName Element
id / type: 0x466E / utf-8
path: \Segment\Attachments\AttachedFile\FileName
minOccurs / maxOccurs: 1 / 1
definition: Filename of the attached file.
5.1.6.1.3. FileMediaType Element
id / type: 0x4660 / string
path: \Segment\Attachments\AttachedFile\FileMediaType
minOccurs / maxOccurs: 1 / 1
definition: Media type of the file following the format described in
[RFC6838].
stream copy: True (Section 8)
5.1.6.1.4. FileData Element
id / type: 0x465C / binary
path: \Segment\Attachments\AttachedFile\FileData
minOccurs / maxOccurs: 1 / 1
definition: The data of the file.
stream copy: True (Section 8)
5.1.6.1.5. FileUID Element
id / type: 0x46AE / uinteger
range: not 0
path: \Segment\Attachments\AttachedFile\FileUID
minOccurs / maxOccurs: 1 / 1
definition: UID representing the file, as random as possible.
stream copy: True (Section 8)
5.1.7. Chapters Element
id / type: 0x1043A770 / master
path: \Segment\Chapters
maxOccurs: 1
recurring: True
definition: A system to define basic menus and partition data. For
more detailed information, see Section 20.
5.1.7.1. EditionEntry Element
id / type: 0x45B9 / master
path: \Segment\Chapters\EditionEntry
minOccurs: 1
definition: Contains all information about a Segment edition.
5.1.7.1.1. EditionUID Element
id / type: 0x45BC / uinteger
range: not 0
path: \Segment\Chapters\EditionEntry\EditionUID
maxOccurs: 1
definition: A UID to identify the edition. It's useful for tagging
an edition.
stream copy: True (Section 8)
5.1.7.1.2. EditionFlagDefault Element
id / type / default: 0x45DB / uinteger / 0
range: 0-1
path: \Segment\Chapters\EditionEntry\EditionFlagDefault
minOccurs / maxOccurs: 1 / 1
definition: Set to 1 if the edition SHOULD be used as the default
one.
5.1.7.1.3. EditionFlagOrdered Element
id / type / default: 0x45DD / uinteger / 0
range: 0-1
path: \Segment\Chapters\EditionEntry\EditionFlagOrdered
minOccurs / maxOccurs: 1 / 1
definition: Set to 1 if the chapters can be defined multiple times
and the order to play them is enforced; see Section 20.1.3.
5.1.7.1.4. ChapterAtom Element
id / type: 0xB6 / master
path: \Segment\Chapters\EditionEntry\+ChapterAtom
minOccurs: 1
recursive: True
definition: Contains the atom information to use as the chapter atom
(applies to all tracks).
5.1.7.1.4.1. ChapterUID Element
id / type: 0x73C4 / uinteger
range: not 0
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterUID
minOccurs / maxOccurs: 1 / 1
definition: A UID to identify the Chapter.
stream copy: True (Section 8)
5.1.7.1.4.2. ChapterStringUID Element
id / type: 0x5654 / utf-8
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterStringUID
maxOccurs: 1
minver: 3
definition: A unique string ID to identify the Chapter. For
example, it is used as the storage for [WebVTT] cue identifier
values.
5.1.7.1.4.3. ChapterTimeStart Element
id / type: 0x91 / uinteger
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTimeStart
minOccurs / maxOccurs: 1 / 1
definition: Timestamp of the start of Chapter expressed in Matroska
Ticks -- i.e., in nanoseconds; see Section 11.1.
5.1.7.1.4.4. ChapterTimeEnd Element
id / type: 0x92 / uinteger
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterTimeEnd
minOccurs / maxOccurs: see implementation notes / 1
definition: Timestamp of the end of Chapter timestamp excluded
expressed in Matroska Ticks -- i.e., in nanoseconds; see
Section 11.1. The value MUST be greater than or equal to the
ChapterTimeStart of the same ChapterAtom.
usage notes: With the ChapterTimeEnd timestamp value being excluded,
it MUST take into account the duration of the last frame it
includes, especially for the ChapterAtom using the last frames of
the Segment.
notes:
+===========+====================================================+
| attribute | note |
+===========+====================================================+
| minOccurs | ChapterTimeEnd MUST be set (minOccurs=1) |
| | if the Edition is an ordered edition; |
| | see Section 20.1.3. If it's a Parent |
| | Chapter, see Section 20.2.3. |
+-----------+----------------------------------------------------+
Table 31: ChapterTimeEnd Implementation Notes
5.1.7.1.4.5. ChapterFlagHidden Element
id / type / default: 0x98 / uinteger / 0
range: 0-1
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterFlagHidden
minOccurs / maxOccurs: 1 / 1
definition: Set to 1 if a chapter is hidden. Hidden chapters SHOULD
NOT be available to the user interface (but still to Control
Tracks; see Section 20.2.5 on Chapter flags).
5.1.7.1.4.6. ChapterSegmentUUID Element
id / type: 0x6E67 / binary
length: 16
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterSegmentUUID
minOccurs / maxOccurs: see implementation notes / 1
definition: The SegmentUUID of another Segment to play during this
chapter.
usage notes: The value MUST NOT be the SegmentUUID value of the
Segment it belongs to.
notes:
+===========+==============================================+
| attribute | note |
+===========+==============================================+
| minOccurs | ChapterSegmentUUID MUST be set (minOccurs=1) |
| | if ChapterSegmentEditionUID is used; see |
| | Section 17.2 on Medium-Linking Segments. |
+-----------+----------------------------------------------+
Table 32: ChapterSegmentUUID Implementation Notes
5.1.7.1.4.7. ChapterSegmentEditionUID Element
id / type: 0x6EBC / uinteger
range: not 0
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterSegmentEdit
ionUID
maxOccurs: 1
definition: The EditionUID to play from the Segment linked in
ChapterSegmentUUID. If ChapterSegmentEditionUID is undeclared,
then no Edition of the linked Segment is used; see Section 17.2 on
Medium-Linking Segments.
5.1.7.1.4.8. ChapterPhysicalEquiv Element
id / type: 0x63C3 / uinteger
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterPhysicalEqu
iv
maxOccurs: 1
definition: Specifies the physical equivalent of this ChapterAtom as
"DVD" (60) or "SIDE" (50); see Section 20.4 for a complete list of
values.
5.1.7.1.4.9. ChapterDisplay Element
id / type: 0x80 / master
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay
definition: Contains all possible strings to use for the chapter
display.
5.1.7.1.4.10. ChapString Element
id / type: 0x85 / utf-8
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Cha
pString
minOccurs / maxOccurs: 1 / 1
definition: Contains the string to use as the chapter atom.
5.1.7.1.4.11. ChapLanguage Element
id / type / default: 0x437C / string / eng
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Cha
pLanguage
minOccurs: 1
definition: A language corresponding to the string in the Matroska
languages form; see Section 12 on language codes. This Element
MUST be ignored if a ChapLanguageBCP47 Element is used within the
same ChapterDisplay Element.
5.1.7.1.4.12. ChapLanguageBCP47 Element
id / type: 0x437D / string
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Cha
pLanguageBCP47
minver: 4
definition: A language corresponding to the ChapString in the
[BCP47] form; see Section 12 on language codes. If a
ChapLanguageBCP47 Element is used, then any ChapLanguage and
ChapCountry Elements used in the same ChapterDisplay MUST be
ignored.
5.1.7.1.4.13. ChapCountry Element
id / type: 0x437E / string
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapterDisplay\Cha
pCountry
definition: A country corresponding to the string in the Matroska
countries form; see Section 13. This Element MUST be ignored if a
ChapLanguageBCP47 Element is used within the same ChapterDisplay
Element.
5.1.7.1.4.14. ChapProcess Element
id / type: 0x6944 / master
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess
definition: Contains all the commands associated to the Atom.
5.1.7.1.4.15. ChapProcessCodecID Element
id / type / default: 0x6955 / uinteger / 0
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr
ocessCodecID
minOccurs / maxOccurs: 1 / 1
definition: Contains the type of the codec used for processing. A
value of 0 means built-in Matroska processing (to be defined) and
a value of 1 means the DVD command set is used; see Section 20.3.
More codec IDs can be added later.
5.1.7.1.4.16. ChapProcessPrivate Element
id / type: 0x450D / binary
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr
ocessPrivate
maxOccurs: 1
definition: Optional data attached to the ChapProcessCodecID
information. For ChapProcessCodecID=1, it is the "DVD level"
equivalent; see Section 20.3.
5.1.7.1.4.17. ChapProcessCommand Element
id / type: 0x6911 / master
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr
ocessCommand
definition: Contains all the commands associated with the Atom.
5.1.7.1.4.18. ChapProcessTime Element
id / type: 0x6922 / uinteger
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr
ocessCommand\ChapProcessTime
minOccurs / maxOccurs: 1 / 1
definition: Defines when the process command SHOULD be handled.
restrictions:
+=======+===============================+
| value | label |
+=======+===============================+
| 0 | during the whole chapter |
+-------+-------------------------------+
| 1 | before starting playback |
+-------+-------------------------------+
| 2 | after playback of the chapter |
+-------+-------------------------------+
Table 33: ChapProcessTime Values
5.1.7.1.4.19. ChapProcessData Element
id / type: 0x6933 / binary
path: \Segment\Chapters\EditionEntry\+ChapterAtom\ChapProcess\ChapPr
ocessCommand\ChapProcessData
minOccurs / maxOccurs: 1 / 1
definition: Contains the command information. The data SHOULD be
interpreted depending on the ChapProcessCodecID value. For
ChapProcessCodecID = 1, the data corresponds to the binary DVD
cell pre/post commands; see Section 20.3.
5.1.8. Tags Element
id / type: 0x1254C367 / master
path: \Segment\Tags
definition: Element containing metadata describing Tracks, Editions,
Chapters, Attachments, or Segments as a whole. A list of valid
tags can be found in [MatroskaTags].
5.1.8.1. Tag Element
id / type: 0x7373 / master
path: \Segment\Tags\Tag
minOccurs: 1
definition: A single metadata descriptor.
5.1.8.1.1. Targets Element
id / type: 0x63C0 / master
path: \Segment\Tags\Tag\Targets
minOccurs / maxOccurs: 1 / 1
definition: Specifies which other elements the metadata represented
by the Tag applies to. If this element is empty or omitted, then
the Tag describes everything in the Segment.
5.1.8.1.1.1. TargetTypeValue Element
id / type / default: 0x68CA / uinteger / 50
path: \Segment\Tags\Tag\Targets\TargetTypeValue
minOccurs / maxOccurs: 1 / 1
definition: A number to indicate the logical level of the target.
defined values:
+=======+===================+================================+
| value | label | definition |
+=======+===================+================================+
| 70 | COLLECTION | The highest hierarchical level |
| | | that tags can describe. |
+-------+-------------------+--------------------------------+
| 60 | EDITION / ISSUE / | A list of lower levels grouped |
| | VOLUME / OPUS / | together. |
| | SEASON / SEQUEL | |
+-------+-------------------+--------------------------------+
| 50 | ALBUM / OPERA / | The most common grouping level |
| | CONCERT / MOVIE / | of music and video (equal to |
| | EPISODE | an episode for TV series). |
+-------+-------------------+--------------------------------+
| 40 | PART / SESSION | When an album or episode has |
| | | different logical parts. |
+-------+-------------------+--------------------------------+
| 30 | TRACK / SONG / | The common parts of an album |
| | CHAPTER | or movie. |
+-------+-------------------+--------------------------------+
| 20 | SUBTRACK / | Corresponds to parts of a |
| | MOVEMENT / SCENE | track for audio, such as a |
| | | movement or scene in a movie. |
+-------+-------------------+--------------------------------+
| 10 | SHOT | The lowest hierarchy found in |
| | | music or movies. |
+-------+-------------------+--------------------------------+
Table 34: TargetTypeValue Values
5.1.8.1.1.2. TargetType Element
id / type: 0x63CA / string
path: \Segment\Tags\Tag\Targets\TargetType
maxOccurs: 1
definition: An informational string that can be used to display the
logical level of the target, such as "ALBUM", "TRACK", "MOVIE",
"CHAPTER", etc.
restrictions:
+============+====================+
| value | label |
+============+====================+
| COLLECTION | TargetTypeValue 70 |
+------------+--------------------+
| EDITION | TargetTypeValue 60 |
+------------+--------------------+
| ISSUE | TargetTypeValue 60 |
+------------+--------------------+
| VOLUME | TargetTypeValue 60 |
+------------+--------------------+
| OPUS | TargetTypeValue 60 |
+------------+--------------------+
| SEASON | TargetTypeValue 60 |
+------------+--------------------+
| SEQUEL | TargetTypeValue 60 |
+------------+--------------------+
| ALBUM | TargetTypeValue 50 |
+------------+--------------------+
| OPERA | TargetTypeValue 50 |
+------------+--------------------+
| CONCERT | TargetTypeValue 50 |
+------------+--------------------+
| MOVIE | TargetTypeValue 50 |
+------------+--------------------+
| EPISODE | TargetTypeValue 50 |
+------------+--------------------+
| PART | TargetTypeValue 40 |
+------------+--------------------+
| SESSION | TargetTypeValue 40 |
+------------+--------------------+
| TRACK | TargetTypeValue 30 |
+------------+--------------------+
| SONG | TargetTypeValue 30 |
+------------+--------------------+
| CHAPTER | TargetTypeValue 30 |
+------------+--------------------+
| SUBTRACK | TargetTypeValue 20 |
+------------+--------------------+
| MOVEMENT | TargetTypeValue 20 |
+------------+--------------------+
| SCENE | TargetTypeValue 20 |
+------------+--------------------+
| SHOT | TargetTypeValue 10 |
+------------+--------------------+
Table 35: TargetType Values
5.1.8.1.1.3. TagTrackUID Element
id / type / default: 0x63C5 / uinteger / 0
path: \Segment\Tags\Tag\Targets\TagTrackUID
definition: A UID to identify the Track(s) that the tags belong to.
usage notes: If the value is 0 at this level, the tags apply to all
tracks in the Segment. If it is set to any other value, it MUST
match the TrackUID value of a track found in this Segment.
5.1.8.1.1.4. TagEditionUID Element
id / type / default: 0x63C9 / uinteger / 0
path: \Segment\Tags\Tag\Targets\TagEditionUID
definition: A UID to identify the EditionEntry(s) that the tags
belong to.
usage notes: If the value is 0 at this level, the tags apply to all
editions in the Segment. If it is set to any other value, it MUST
match the EditionUID value of an edition found in this Segment.
5.1.8.1.1.5. TagChapterUID Element
id / type / default: 0x63C4 / uinteger / 0
path: \Segment\Tags\Tag\Targets\TagChapterUID
definition: A UID to identify the Chapter(s) the tags belong to.
usage notes: If the value is 0 at this level, the tags apply to all
chapters in the Segment. If it is set to any other value, it MUST
match the ChapterUID value of a chapter found in this Segment.
5.1.8.1.1.6. TagAttachmentUID Element
id / type / default: 0x63C6 / uinteger / 0
path: \Segment\Tags\Tag\Targets\TagAttachmentUID
definition: A UID to identify the Attachment(s) the tags belong to.
usage notes: If the value is 0 at this level, the tags apply to all
the attachments in the Segment. If it is set to any other value,
it MUST match the FileUID value of an attachment found in this
Segment.
5.1.8.1.2. SimpleTag Element
id / type: 0x67C8 / master
path: \Segment\Tags\Tag\+SimpleTag
minOccurs: 1
recursive: True
definition: Contains general information about the target.
5.1.8.1.2.1. TagName Element
id / type: 0x45A3 / utf-8
path: \Segment\Tags\Tag\+SimpleTag\TagName
minOccurs / maxOccurs: 1 / 1
definition: The name of the Tag that is going to be stored.
5.1.8.1.2.2. TagLanguage Element
id / type / default: 0x447A / string / und
path: \Segment\Tags\Tag\+SimpleTag\TagLanguage
minOccurs / maxOccurs: 1 / 1
definition: Specifies the language of the specified tag in the
Matroska languages form; see Section 12 on language codes. This
Element MUST be ignored if the TagLanguageBCP47 Element is used
within the same SimpleTag Element.
5.1.8.1.2.3. TagLanguageBCP47 Element
id / type: 0x447B / string
path: \Segment\Tags\Tag\+SimpleTag\TagLanguageBCP47
maxOccurs: 1
minver: 4
definition: The language used in the TagString in the [BCP47] form;
see Section 12. If this Element is used, then any TagLanguage
Elements used in the same SimpleTag MUST be ignored.
5.1.8.1.2.4. TagDefault Element
id / type / default: 0x4484 / uinteger / 1
range: 0-1
path: \Segment\Tags\Tag\+SimpleTag\TagDefault
minOccurs / maxOccurs: 1 / 1
definition: A boolean value to indicate if this is the default/
original language to use for the given tag.
5.1.8.1.2.5. TagString Element
id / type: 0x4487 / utf-8
path: \Segment\Tags\Tag\+SimpleTag\TagString
maxOccurs: 1
definition: The value of the Tag.
5.1.8.1.2.6. TagBinary Element
id / type: 0x4485 / binary
path: \Segment\Tags\Tag\+SimpleTag\TagBinary
maxOccurs: 1
definition: The values of the Tag if it is binary. Note that this
cannot be used in the same SimpleTag as TagString.
6. Matroska Element Ordering
With the exceptions of the EBML Header and the CRC-32 Element, the
EBML specification does not require any particular storage order for
Elements. However, this specification defines, mandates, and
recommends the order of certain Elements to facilitate better
playback, seeking, and editing efficiency. This section describes
and offers rationale for ordering requirements and recommendations
for Matroska.
6.1. Top-Level Elements
The Info Element is the only REQUIRED Top-Level Element in a Matroska
file. To be playable, Matroska MUST also contain at least one Tracks
Element and Cluster Element. The first Info Element and the first
Tracks Element MUST either be stored before the first Cluster Element
or both SHALL be referenced by a SeekHead Element occurring before
the first Cluster Element.
All Top-Level Elements MUST use an EBML Element ID that is 4 octets
long.
When using Medium Linking, chapters are used to reference other
Segments to play in a given order Section 17.2. A Segment containing
these Linked Chapters does not require a Track Element or a Cluster
Element.
It is possible to edit a Matroska file after it has been created.
For example, chapters, tags, or attachments can be added. When new
Top-Level Elements are added to a Matroska file, the SeekHead
Element(s) MUST be updated so that the SeekHead Element(s) itemize
the identity and position of all Top-Level Elements.
Editing, removing, or adding Elements to a Matroska file often
requires that some existing Elements be voided or extended.
Transforming the existing Elements into Void Elements as padding can
be used as a method to avoid moving large amounts of data around.
6.2. CRC-32
As noted by the EBML specification, if a CRC-32 Element is used, then
the CRC-32 Element MUST be the first ordered Element within its
Parent Element.
In Matroska, all Top-Level Elements of an EBML Document SHOULD
include a CRC-32 Element as their first Child Element. The Segment
Element, which is the Root Element, SHOULD NOT have a CRC-32 Element.
6.3. SeekHead
If used, the first SeekHead Element MUST be the first non-CRC-32
Child Element of the Segment Element. If a second SeekHead Element
is used, then the first SeekHead Element MUST reference the identity
and position of the second SeekHead Element.
Additionally, the second SeekHead Element MUST only reference Cluster
Elements and not any other Top-Level Element already contained within
the first SeekHead Element.
The second SeekHead Element MAY be stored in any order relative to
the other Top-Level Elements. Whether one or two SeekHead Element(s)
are used, the SeekHead Element(s) MUST collectively reference the
identity and position of all Top-Level Elements except for the first
SeekHead Element.
6.4. Cues (Index)
The Cues Element is RECOMMENDED to optimize seeking access in
Matroska. It is programmatically simpler to add the Cues Element
after all Cluster Elements have been written because this does not
require a prediction of how much space to reserve before writing the
Cluster Elements. However, storing the Cues Element before the
Cluster Elements can provide some seeking advantages. If the Cues
Element is present, then it SHOULD either be stored before the first
Cluster Element or be referenced by a SeekHead Element.
6.5. Info
The first Info Element SHOULD occur before the first Tracks Element
and first Cluster Element except when it is referenced by a SeekHead
Element.
6.6. Chapters Element
The Chapters Element SHOULD be placed before the Cluster Element(s).
The Chapters Element can be used during playback even if the user
does not need to seek. It immediately gives the user information
about what section is being read and what other sections are
available. In the case of Ordered Chapters, it is RECOMMENDED to
evaluate the logical linking even before playing. The Chapters
Element SHOULD be placed before the first Tracks Element and after
the first Info Element.
6.7. Attachments
The Attachments Element is not intended to be used by default when
playing the file, but could contain information relevant to the
content, such as cover art or fonts. Cover art is useful even before
the file is played and fonts could be needed before playback starts
for the initialization of subtitles. The Attachments Element MAY be
placed before the first Cluster Element; however, if the Attachments
Element is likely to be edited, then it SHOULD be placed after the
last Cluster Element.
6.8. Tags
The Tags Element is most subject to changes after the file was
originally created. For easier editing, the Tags Element can be
placed at the end of the Segment Element and after the Attachments
Element. On the other hand, it is inconvenient to have to seek in
the Segment for tags, especially for network streams; thus, it's
better if the Tags Element is found early in the stream. When
editing the Tags Element, the original Tags Element at the beginning
can be overwritten with a Void Element and a new Tags Element written
at the end of the Segment Element. The file and Segment sizes will
only marginally change.
7. Matroska Versioning
Matroska is based on the principle that a reading application does
not have to support 100% of the specifications in order to be able to
play the file. Therefore, a Matroska file contains version
indicators that tell a reading application what to expect.
It is possible and valid to have the version fields indicate that the
file contains Matroska Elements from a higher specification version
number while signaling that a reading application MUST only support a
lower version number properly in order to play it back (possibly with
a reduced feature set).
The EBML Header of each Matroska document informs the reading
application on what version of Matroska to expect. The Elements
within the EBML Header with jurisdiction over this information are
DocTypeVersion and DocTypeReadVersion.
DocTypeVersion MUST be equal to or greater than the highest Matroska
version number of any Element present in the Matroska file. For
example, a file using the SimpleBlock Element (Section 5.1.3.4) MUST
have a DocTypeVersion equal to or greater than 2. A file containing
CueRelativePosition Elements (Section 5.1.5.1.2.3) MUST have a
DocTypeVersion equal to or greater than 4.
The DocTypeReadVersion MUST contain the minimum version number that a
reading application can minimally support in order to play the file
back -- optionally with a reduced feature set. For example, if a
file contains only Elements of version 2 or lower except for
CueRelativePosition (which is a version 4 Matroska Element), then
DocTypeReadVersion SHOULD still be set to 2 and not 4 because
evaluating CueRelativePosition is not necessary for standard playback
-- it makes seeking more precise if used.
A reading application supporting Matroska version V MUST NOT refuse
to read a file with DocReadTypeVersion equal to or lower than V, even
if DocTypeVersion is greater than V.
A reading application supporting Matroska version V at minimum and
reading a file whose DocTypeReadVersion field is equal to or lower
than V MUST skip Matroska / EBML Elements it encounters but does not
know about if that unknown element fits into the size constraints set
by the current Parent Element.
8. Stream Copy
It is sometimes necessary to create a Matroska file from another
Matroska file; e.g., to add subtitles in a language or to edit out a
portion of the content. Some values from the original Matroska file
need to be kept the same in the destination file. For example, the
SamplingFrequency of an audio track wouldn't change between the two
files. Some other values may change between the two files, such as
the TrackNumber of an audio track when another track has been added.
An Element is marked with the property "stream copy: True" when the
values of that Element need to be kept identical between the source
and destination files. If that property is not set, elements may or
may not keep the same value between the source and destination files.
9. DefaultDecodedFieldDuration
The DefaultDecodedFieldDuration Element can signal to the displaying
application how often fields of a video sequence will be available
for displaying. It can be used for both interlaced and progressive
content.
If the video sequence is signaled as interlaced Section 5.1.4.1.28.1,
then DefaultDecodedFieldDuration equals the period between two
successive fields at the output of the decoding process. For video
sequences signaled as progressive, DefaultDecodedFieldDuration is
half of the period between two successive frames at the output of the
decoding process.
These values are valid at the end of the decoding process before
post-processing (such as deinterlacing or inverse telecine) is
applied.
Examples:
* Blu-ray movie: 1000000000 ns/(48/1.001) = 20854167 ns
* PAL broadcast/DVD: 1000000000 ns/(50/1.000) = 20000000 ns
* N/ATSC broadcast: 1000000000 ns/(60/1.001) = 16683333 ns
* Hard-telecined DVD: 1000000000 ns/(60/1.001) = 16683333 ns (60
encoded interlaced fields per second)
* Soft-telecined DVD: 1000000000 ns/(60/1.001) = 16683333 ns (48
encoded interlaced fields per second, with "repeat_first_field =
1")
10. Cluster Blocks
Frames using references SHOULD be stored in "coding order", i.e.,
storing the references first and then the frames referencing them. A
consequence is that timestamps might not be consecutive. However, a
frame with a past timestamp MUST reference a frame already known.
Otherwise, the frame is considered bad/void.
Matroska has two similar ways to store frames in a block:
* In a Block, which is contained inside a BlockGroup.
* In a SimpleBlock, which is directly in the Cluster.
The SimpleBlock is usually preferred unless some extra elements of
the BlockGroup need to be used. A Matroska Reader MUST support both
types of blocks.
Each block contains the same parts in the following order:
* A header that is variable in length,
* the lacing information (optional), and
* the consecutive frame(s).
The block header starts with the number of the Track it corresponds
to. The value MUST correspond to the TrackNumber (Section 5.1.4.1.1)
of a TrackEntry of the Segment.
The TrackNumber is coded using the Variable-Size Integer (VINT)
mechanism described in Section 4 of [RFC8794]. To save space, the
shortest VINT form SHOULD be used. The value can be coded on up to 8
octets. This is the only element with a variable size in the block
header.
The timestamp is expressed in Track Ticks; see Section 11.1. The
value is stored as a signed value on 16 bits.
10.1. Block Structure
This section describes the binary data contained in the Block Element
(Section 5.1.3.5.1). Bit 0 is the most significant bit.
As the TrackNumber size can vary between 1 and 8 octets, there are 8
different sizes for the Block header. The definitions for
TrackNumber sizes of 1 and 2 are provided; the other variants can be
deduced by extending the size of the TrackNumber by multiples of 8
bits.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |I|LAC|U|
| Track Number | Timestamp | Rsvrd |N|ING|N|
| | | |V| |U|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Block Header with 1 Octet TrackNumber
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Track Number | Timestamp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |I|LAC|U|
| Rsvrd |N|ING|N| ...
| |V| |U|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Block Header with 2 Octets TrackNumber
where:
Track Number: 8, 16, 24, 32, 40, 48 or 64 bits. An EBML VINT-coded
track number.
Timestamp: 16 bits. Signed timestamp in Track Ticks.
Rsvrd: 4 bits. Reserved bits MUST be set to 0.
INV: 1 bit. Invisible. The codec SHOULD decode this frame but not
display it.
LACING: 2 bits. Uses lacing mode.
00b: no lacing (Section 10.3.1)
01b: Xiph lacing (Section 10.3.2)
11b: EBML lacing (Section 10.3.3)
10b: fixed-size lacing (Section 10.3.4)
UNU: 1 bit that is unused.
The following data in the Block corresponds to the lacing data and
frames usage as described in each respective lacing mode.
10.2. SimpleBlock Structure
This section describes the binary data contained in the SimpleBlock
Element (Section 5.1.3.4). Bit 0 is the most significant bit.
The SimpleBlock structure is inspired by the Block structure; see
Section 10.1. The main differences are the added Keyframe flag and
Discardable flag. Otherwise, everything is the same.
As the TrackNumber size can vary between 1 and 8 octets, there are 8
different sizes for the SimpleBlock header. The definitions for
TrackNumber sizes of 1 and 2 are provided; the other variants can be
deduced by extending the size of the TrackNumber by multiples of 8
bits.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |K| |I|LAC|D|
| Track Number | Timestamp |E|Rsvrd|N|ING|I|
| | |Y| |V| |S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: SimpleBlock Header with 1 Octet TrackNumber
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Track Number | Timestamp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|K| |I|LAC|D|
|E|Rsvrd|N|ING|I| ...
|Y| |V| |S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: SimpleBlock Header with 2 Octets TrackNumber
where:
Track Number: 8, 16, 24, 32, 40, 48 or 64 bits. An EBML VINT-coded
track number.
Timestamp: 16 bits. Signed timestamp in Track Ticks.
KEY: 1 bit. Keyframe. Set when the Block contains only keyframes.
Rsvrd: 3 bits. Reserved bits MUST be set to 0.
INV: 1 bit. Invisible. The codec SHOULD decode this frame but not
display it.
LACING: 2 bits. Uses lacing mode.
00b: no lacing (Section 10.3.1)
01b: Xiph lacing (Section 10.3.2)
11b: EBML lacing (Section 10.3.3)
10b: fixed-size lacing (Section 10.3.4)
DIS: 1 bit. Discardable. The frames of the Block can be discarded
during playing if needed.
The following data in the SimpleBlock correspond to the lacing data
and frames usage as described in each respective lacing mode.
10.3. Block Lacing
Lacing is a mechanism to save space when storing data. It is
typically used for small blocks of data (referred to as frames in
Matroska). It packs multiple frames into a single Block or
SimpleBlock.
Lacing MUST NOT be used to store a single frame in a Block or
SimpleBlock.
There are three types of lacing:
* Xiph, which is inspired by what is found in the Ogg container
[RFC3533].
* EBML, which is the same with sizes coded differently.
* Fixed-size, where the size is not coded.
When lacing is not used, i.e., to store a single frame, lacing bits 5
and 6 of the Block or SimpleBlock MUST be set to 0.
For example, a user wants to store 3 frames of the same track. The
first frame is 800 octets long, the second is 500 octets long, and
the third is 1000 octets long. Since these frames are small, they
can be stored in a lace to save space.
It is possible to not use lacing at all and just store a single frame
without any extra data. When the FlagLacing (Section 5.1.4.1.12) is
set to "0", all blocks of that track MUST NOT use lacing.
10.3.1. No Lacing
When no lacing is used, the number of frames in the lace is ommitted
and only one frame can be stored in the Block. Bits 5 and 6 of the
Block Header flags are set to 0b00.
The Block for an 800-octet frame is as follows:
+==============+=========+===================+
| Block Octets | Value | Description |
+==============+=========+===================+
| 4-803 | | Single frame data |
+--------------+---------+-------------------+
Table 36: No Lacing
When a Block contains a single frame, it MUST use this No lacing
mode.
10.3.2. Xiph Lacing
The Xiph lacing uses the same coding of size as found in the Ogg
container [RFC3533]. Bits 5 and 6 of the Block Header flags are set
to 0b01.
The Block data with laced frames is stored as follows:
* Lacing Head on 1 octet: Number of frames in the lace minus 1.
* Lacing size of each frame except the last one.
* Binary data of each frame consecutively.
The lacing size is split into 255 values, stored as unsigned octets
-- for example, 500 is coded 255;245 or [0xFF 0xF5]. A frame with a
size multiple of 255 is coded with a 0 at the end of the size -- for
example, 765 is coded 255;255;255;0 or [0xFF 0xFF 0xFF 0x00].
The size of the last frame is deduced from the size remaining in the
Block after the other frames.
Because large sizes result in large coding of the sizes, it is
RECOMMENDED to use Xiph lacing only with small frames.
In our example, the 800, 500, and 1000-octet frames are stored with
Xiph lacing in a Block as follows:
+==============+=====================+==========================+
| Block Octets | Value | Description |
+==============+=====================+==========================+
| 4 | 0x02 | Number of frames minus 1 |
+--------------+---------------------+--------------------------+
| 5-8 | 0xFF 0xFF 0xFF 0x23 | Size of the first frame |
| | | (255; 255; 255; 35) |
+--------------+---------------------+--------------------------+
| 9-10 | 0xFF 0xF5 | Size of the second frame |
| | | (255; 245) |
+--------------+---------------------+--------------------------+
| 11-810 | | First frame data |
+--------------+---------------------+--------------------------+
| 811-1310 | | Second frame data |
+--------------+---------------------+--------------------------+
| 1311-2310 | | Third frame data |
+--------------+---------------------+--------------------------+
Table 37: Xiph Lacing Example
The Block is 2311 octets and the last frame starts at 1311, so we can
deduce that the size of the last frame is 2311 - 1311 = 1000.
10.3.3. EBML Lacing
The EBML lacing encodes the frame size with an EBML-like encoding
[RFC8794]. Bits 5 and 6 of the Block Header flags are set to 0b11.
The Block data with laced frames is stored as follows:
* Lacing Head on 1 Octet: Number of frames in the lace minus 1.
* Lacing size of each frame except the last one.
* Binary data of each frame consecutively.
The first frame size is encoded as an EBML VINT value. The remaining
frame sizes are encoded as signed values using the difference between
the frame size and the previous frame size. These signed values are
encoded as VINT with a mapping from signed to unsigned numbers.
Decoding the unsigned number stored in the VINT to a signed number is
done by subtracting 2^((7*n)-1)-1, where n is the octet size of the
VINT.
+===================================+======================+
| Bit Representation of Signed VINT | Possible Value Range |
+===================================+======================+
| 1xxx xxxx | 2^7 values from |
| | -(2^6-1) to 2^6 |
+-----------------------------------+----------------------+
| 01xx xxxx xxxx xxxx | 2^14 values from |
| | -(2^13-1) to 2^13 |
+-----------------------------------+----------------------+
| 001x xxxx xxxx xxxx xxxx xxxx | 2^21 values from |
| | -(2^20-1) to 2^20 |
+-----------------------------------+----------------------+
| 0001 xxxx xxxx xxxx xxxx xxxx | 2^28 values from |
| xxxx xxxx | -(2^27-1) to 2^27 |
+-----------------------------------+----------------------+
| 0000 1xxx xxxx xxxx xxxx xxxx | 2^35 values from |
| xxxx xxxx xxxx xxxx | -(2^34-1) to 2^34 |
+-----------------------------------+----------------------+
Table 38: EBML Lacing Signed VINT Bits Usage
In our example, the 800, 500 and 1000-octet frames are stored with
EBML lacing in a Block as follows:
+==============+===========+=====================================+
| Block Octets | Value | Description |
+==============+===========+=====================================+
| 4 | 0x02 | Number of frames minus 1 |
+--------------+-----------+-------------------------------------+
| 5-6 | 0x43 0x20 | Size of the first frame (800 = |
| | | 0x320 + 0x4000) |
+--------------+-----------+-------------------------------------+
| 7-8 | 0x5E 0xD3 | Size of the second frame (500 - 800 |
| | | = -300 = - 0x12C + 0x1FFF + 0x4000) |
+--------------+-----------+-------------------------------------+
| 8-807 | | First frame data |
+--------------+-----------+-------------------------------------+
| 808-1307 | | Second frame data |
+--------------+-----------+-------------------------------------+
| 1308-2307 | | Third frame data |
+--------------+-----------+-------------------------------------+
Table 39: EBML Lacing Example
The Block is 2308 octets and the last frame starts at 1308, so we can
deduce that the size of the last frame is 2308 - 1308 = 1000.
10.3.4. Fixed-size Lacing
Fixed-size lacing doesn't store the frame size; rather, it only
stores the number of frames in the lace. Each frame MUST have the
same size. The frame size of each frame is deduced from the total
size of the Block. Bits 5 and 6 of the Block Header flags are set to
0b10.
The Block data with laced frames is stored as follows:
* Lacing Head on 1 Octet: Number of frames in the lace minus 1.
* Binary data of each frame consecutively.
For example, for three frames that are 800 octets each:
+==============+==========+==========================+
| Block Octets | Value | Description |
+==============+==========+==========================+
| 4 | 0x02 | Number of frames minus 1 |
+--------------+----------+--------------------------+
| 5-804 | | First frame data |
+--------------+----------+--------------------------+
| 805-1604 | | Second frame data |
+--------------+----------+--------------------------+
| 1605-2404 | | Third frame data |
+--------------+----------+--------------------------+
Table 40: Fixed-Size Lacing Example
This gives a Block of 2405 octets. When reading the Block, we find
that there are three frames (Octet 4). The data start at Octet 5, so
the size of each frame is (2405 - 5) / 3 = 800.
10.3.5. Laced Frames Timestamp
A Block only contains a single timestamp value. But when lacing is
used, it contains more than one frame. Each frame originally has its
own timestamp, or Presentation Timestamp (PTS). That timestamp
applies to the first frame in the lace.
In the lace, each frame after the first one has an underdetermined
timestamp. However, each of these frames MUST be contiguous, i.e.,
the decoded data MUST NOT contain any gap between them. If there is
a gap in the stream, the frames around the gap MUST NOT be in the
same Block.
Lacing is only useful for small contiguous data to save space. This
is usually the case for audio tracks and not the case for video
(which use a lot of data) or subtitle tracks (which have long gaps).
For audio, there is usually a fixed output sampling frequency for the
whole track, so the decoder should be able to recover the timestamp
of each sample knowing each output sample is contiguous with a fixed
frequency. For subtitles, this is usually not the case; therefore,
lacing SHOULD NOT be used.
10.4. Random Access Points
Random Access Points (RAPs) are positions where the parser can seek
to and start playback without decoding of what was before. In
Matroska, BlockGroups and SimpleBlocks can be RAPs. To seek to these
elements, it is still necessary to seek to the Cluster containing
them, read the Cluster Timestamp, and start playback from the
BlockGroup or SimpleBlock that is a RAP.
Because a Matroska File is usually composed of multiple tracks
playing at the same time -- video, audio and subtitles -- to seek
properly to a RAP, each selected track must be taken in account.
Usually, all audio and subtitle BlockGroups or SimpleBlocks are RAPs.
They are independent of each other and can be played randomly.
On the other hand, video tracks often use references to previous and
future frames for better coding efficiency. Frames with such
references MUST either contain one or more ReferenceBlock Elements in
their BlockGroup or MUST be marked as non-keyframe in a SimpleBlock;
see Section 10.2.
* BlockGroup with a frame that references another frame, with the
EBML tree shown as XML:
123456
-40
...
* SimpleBlock with a frame that references another frame, with the
EBML tree shown as XML:
123456
(octet 3 bit 0 not set)
...
Frames that are RAPs (i.e., frames that don't depend on other frames)
MUST set the keyframe flag if they are in a SimpleBlock or their
parent BlockGroup MUST NOT contain a ReferenceBlock.
* BlockGroup with a frame that references no other frame, with the
EBML tree shown as XML:
123456
...
* SimpleBlock with a frame that references no other frame, with the
EBML tree shown as XML:
123456
(octet 3 bit 0 set)
...
There may be cases where the use of BlockGroup is necessary, as the
frame may need a BlockDuration, BlockAdditions, CodecState, or
DiscardPadding element. For thoses cases, a SimpleBlock MUST NOT be
used; rather, the reference information SHOULD be recovered for non-
RAP frames.
* SimpleBlock with a frame that references another frame, with the
EBML tree shown as XML:
123456
(octet 3 bit 0 not set)
...
* Same frame that references another frame put inside a BlockGroup
to add BlockDuration, with the EBML tree shown as XML:
123456
-40
20
...
When a frame in a BlockGroup is not a RAP, the BlockGroup MUST
contain at least a ReferenceBlock. The ReferenceBlocks MUST be used
in one of the following ways:
* Each reference frame listed as a ReferenceBlock;
* some referenced frame listed as a ReferenceBlock, even if the
timestamp value is accurate; or
* one ReferenceBlock with the timestamp value "0" corresponding to a
self or unknown reference.
The lack of ReferenceBlock would mean such a frame is a RAP and
seeking on that frame that actually depends on other frames may
create a bogus output or even crash.
* Same frame that references another frame put inside a BlockGroup
but the reference could not be recovered, with the EBML tree shown
as XML:
123456
0
20
...
* BlockGroup with a frame that references two other frames, with the
EBML tree shown as XML:
123456
-80
40
...
Intra-only video frames, such as the ones found in AV1 or VP9, can be
decoded without any other frame, but they don't reset the codec
state. Thus, seeking to these frames is not possible, as the next
frames may need frames that are not known from this seeking point.
Such intra-only frames MUST NOT be considered as keyframes, so the
keyframe flag MUST NOT be set in the SimpleBlock or a ReferenceBlock
MUST be used to signify the frame is not a RAP. The timestamp value
of the ReferenceBlock MUST be "0", meaning it's referencing itself.
* Intra-only frame not an RAP, with the EBML tree shown as XML:
123456
0
...
Because a video SimpleBlock has less information on references than a
video BlockGroup, it is possible to remux a video track using
BlockGroup into a SimpleBlock as long as it doesn't use any other
BlockGroup features than ReferenceBlock.
11. Timestamps
Historically, timestamps in Matroska were mistakenly called
timecodes. The Timestamp Element was called Timecode, the
TimestampScale Element was called TimecodeScale, the
TrackTimestampScale Element was called TrackTimecodeScale, and the
ReferenceTimestamp Element was called ReferenceTimeCode.
11.1. Timestamp Ticks
All timestamp values in Matroska are expressed in multiples of a
tick. They are usually stored as integers. There are three types of
ticks possible: Matroska Ticks, Segment Ticks, and Track Ticks.
11.1.1. Matroska Ticks
For such elements, the timestamp value is stored directly in
nanoseconds.
The elements storing values in Matroska Ticks/nanoseconds are:
* TrackEntry\DefaultDuration; defined in Section 5.1.4.1.13
* TrackEntry\DefaultDecodedFieldDuration; defined in
Section 5.1.4.1.14
* TrackEntry\SeekPreRoll; defined in Section 5.1.4.1.26
* TrackEntry\CodecDelay; defined in Section 5.1.4.1.25
* BlockGroup\DiscardPadding; defined in Section 5.1.3.5.7
* ChapterAtom\ChapterTimeStart; defined in Section 5.1.7.1.4.3
* ChapterAtom\ChapterTimeEnd; defined in Section 5.1.7.1.4.4
* CuePoint\CueTime; defined in Section 5.1.5.1.1
* CueReference\CueRefTime; defined in Section 5.1.5.1.1
11.1.2. Segment Ticks
Elements in Segment Ticks involve the use of the TimestampScale
Element of the Segment to get the timestamp in nanoseconds of the
element with the following formula:
timestamp in nanosecond = element value * TimestampScale
This allows for storage of smaller integer values in the elements.
When using the default value of "1,000,000" for TimestampScale, one
Segment Tick represents one millisecond.
The elements storing values in Segment Ticks are:
* Cluster\Timestamp; defined in Section 5.1.3.1
* Info\Duration is stored as a floating-point, but the same formula
applies; defined in Section 5.1.2.10
* CuePoint\CueTrackPositions\CueDuration; defined in
Section 5.1.5.1.2.4
11.1.3. Track Ticks
Elements in Track Ticks involve the use of the TimestampScale Element
of the Segment and the TrackTimestampScale Element of the Track to
get the timestamp in nanoseconds of the element with the following
formula:
timestamp in nanoseconds =
element value * TrackTimestampScale * TimestampScale
This allows for storage of smaller integer values in the elements.
The resulting floating-point values of the timestamps are still
expressed in nanoseconds.
When using the default values of "1,000,000" for TimestampScale and
"1.0" for TrackTimestampScale, one Track Tick represents one
millisecond.
The elements storing values in Track Ticks are:
* Cluster\BlockGroup\Block and Cluster\SimpleBlock timestamps;
detailed in Section 11.2
* Cluster\BlockGroup\BlockDuration; defined in Section 5.1.3.5.3
* Cluster\BlockGroup\ReferenceBlock; defined in Section 5.1.3.5.5
When the TrackTimestampScale is interpreted as "1.0", Track Ticks are
equivalent to Segment Ticks and give an integer value in nanoseconds.
This is the most common case as TrackTimestampScale is usually
omitted.
A value of TrackTimestampScale other than 1.0 MAY be used to scale
the timestamps more in tune with each Track sampling frequency. For
historical reasons, a lot of Matroska readers don't take the
TrackTimestampScale value into account; thus, using a value other
than 1.0 might not work in many places.
11.2. Block Timestamps
A Block Element and SimpleBlock Element timestamp is the time when
the decoded data of the first frame in the Block/SimpleBlock MUST be
presented if the track of that Block/SimpleBlock is selected for
playback. This is also known as the PTS.
The Block Element and SimpleBlock Element store their timestamps as
signed integers, relative to the Cluster\Timestamp value of the
Cluster they are stored in. To get the timestamp of a Block or
SimpleBlock in nanoseconds, the following formula has to be used:
( Cluster\Timestamp + ( block timestamp * TrackTimestampScale ) ) *
TimestampScale
The Block Element and SimpleBlock Element store their timestamps as
16-bit signed integers, allowing a range from "-32768" to "+32767"
Track Ticks. Although these values can be negative, when added to
the Cluster\Timestamp, the resulting frame timestamp SHOULD NOT be
negative.
When a CodecDelay Element is set, its value MUST be substracted from
each Block timestamp of that track. To get the timestamp in
nanoseconds of the first frame in a Block or SimpleBlock, the formula
becomes:
( ( Cluster\Timestamp + ( block timestamp * TrackTimestampScale ) ) *
TimestampScale ) - CodecDelay
The resulting frame timestamp SHOULD NOT be negative.
During playback, when a frame has a negative timestamp, the content
MUST be decoded by the decoder, but not played to the user.
11.3. TimestampScale Rounding
The default Track Tick duration is one millisecond.
The TimestampScale is a floating-point value that is usually 1.0.
When it's not 1.0, the multiplied Block Timestamp is a floating-point
value in nanoseconds. The Matroska Reader SHOULD use the nearest
rounding value in nanoseconds to get the proper nanosecond timestamp
of a Block. This allows some clever TimestampScale values to have a
more refined timestamp precision per frame.
12. Language Codes
Matroska from version 1 through 3 uses language codes that can be
either the 3 letters bibliographic ISO 639-2 form [ISO639-2] (like
"fre" for French), or such a language code followed by a dash and a
country code for specialities in languages (like "fre-ca" for
Canadian French). The ISO 639-2 Language Elements are "Language
Element", "TagLanguage Element", and "ChapLanguage Element".
Starting in Matroska version 4, either [ISO639-2] or [BCP47] MAY be
used, although BCP 47 is RECOMMENDED. The BCP 47 Language Elements
are "LanguageBCP47 Element", "TagLanguageBCP47 Element", and
"ChapLanguageBCP47 Element". If a BCP 47 Language Element and an ISO
639-2 Language Element are used within the same Parent Element, then
the ISO 639-2 Language Element MUST be ignored; precedence is given
to the BCP 47 Language Element.
13. Country Codes
Country codes are the [BCP47] two-letter region subtags without the
UK exception.
14. Encryption
This Matroska specification provides no interoperable solution for
securing the data container with any assurances of confidentiality,
integrity, authenticity, or to provide authorization. The
ContentEncryption Element (Section 5.1.4.1.31.8) and associated sub-
fields (Section 5.1.4.1.31.9 to Section 5.1.4.1.31.12) are defined
only for the benefit of implementers to construct their own
proprietary solution or as the basis for further standardization
activities. How to use these fields to secure a Matroska data
container is out of scope, as are any related issues, such as key
management and distribution.
A Matroska Reader who encounters containers that use the fields
defined in this section MUST rely on out-of-scope guidance to decode
the associated content.
Because encryption occurs within the Block Element, it is possible to
manipulate encrypted streams without decrypting them. The streams
could potentially be copied, deleted, cut, appended, or any number of
other possible editing techniques without decryption. The data can
be used without having to expose it or go through the decrypting
process.
Encryption can also be layered within Matroska. This means that two
completely different types of encryption can be used, requiring two
separate keys to be able to decrypt a stream.
Encryption information is stored in the ContentEncodings Element
under the ContentEncryption Element.
For encryption systems sharing public/private keys, the creation of
the keys and the exchange of keys are not covered by this document.
They have to be handled by the system using Matroska.
The algorithms described in Table 26 support different modes of
operations and key sizes. The specification of these parameters is
required for a complete solution, but is out of scope of this
document and left to the proprietary implementations using them or
subsequent profiles of this document.
The ContentEncodingScope Element gives an idea of which part of the
track is encrypted, but each ContentEncAlgo Element and its sub-
elements (such as AESSettingsCipherMode) define exactly how the
encrypted track should be interpreted.
An example of an extension that builds upon these security-related
fields in this specification is [WebM-Enc]. It uses AES-CTR,
ContentEncAlgo = 5 (Section 5.1.4.1.31.9), and AESSettingsCipherMode
= 1 (Section 5.1.4.1.31.12).
A Matroska Writer MUST NOT use insecure cryptographic algorithms to
create new archives or streams, but a Matroska Reader MAY support
these algorithms to read previously made archives or streams.
15. Image Presentation
15.1. Cropping
The PixelCrop Elements (PixelCropTop, PixelCropBottom,
PixelCropRight, and PixelCropLeft) indicate when, and by how much,
encoded video frames SHOULD be cropped for display. These Elements
allow edges of the frame that are not intended for display to be
stored, but hidden. Examples include the sprockets of a full-frame
film scan or the VANC area of a digitized analog videotape.
PixelCropTop and PixelCropBottom store an integer of how many rows of
pixels SHOULD be cropped from the top and bottom of the image,
respectively. PixelCropLeft and PixelCropRight store an integer of
how many columns of pixels SHOULD be cropped from the left and right
of the image, respectively.
For example, a pillar-boxed video that stores a 1440x1080 visual
image within the center of a padded 1920x1080 encoded image may set
both PixelCropLeft and PixelCropRight to "240" so that a Matroska
Player can crop off 240 columns of pixels from the left and right of
the encoded image to present the image with the pillar-boxes hidden.
Cropping has to be performed before resizing and the display
dimensions given by DisplayWidth, DisplayHeight, and DisplayUnit
apply to the image that is already cropped.
15.2. Rotation
The ProjectionPoseRoll Element (Section 5.1.4.1.28.46) can be used to
indicate that the image from the associated video track SHOULD be
rotated for presentation. For instance, the following example of the
Projection Element (Section 5.1.4.1.28.41) and the ProjectionPoseRoll
Element represents a video track where the image SHOULD be presented
with a 90-degree counter-clockwise rotation, with the EBML tree shown
as XML:
90
Figure 15: Rotation Example
16. Segment Position
The Segment Position of an Element refers to the position of the
first octet of the Element ID of that Element, measured in octets,
from the beginning of the Element Data section of the containing
Segment Element. In other words, the Segment Position of an Element
is the distance in octets from the beginning of its containing
Segment Element minus the size of the Element ID and Element Data
Size of that Segment Element. The Segment Position of the first
Child Element of the Segment Element is 0. An Element that is not
stored within a Segment Element, such as the Elements of the EBML
Header, do not have a Segment Position.
16.1. Segment Position Exception
Elements that are defined to store a Segment Position MAY define
reserved values to indicate a special meaning.
16.2. Example of Segment Position
This table presents an example of a Segment Position by showing a
hexadecimal representation of a very small Matroska file with labels
to show the offsets in octets. The file contains a Segment Element
with an Element ID of "0x18538067" and a MuxingApp Element with an
Element ID of "0x4D80".
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
0 |1A|45|DF|A3|8B|42|82|88|6D|61|74|72|6F|73|6B|61|
^ EBML Header
0 | |18|53|80|67|
^ Segment ID
20 |93|
^ Segment Data Size
20 | |15|49|A9|66|8E|4D|80|84|69|65|74|66|57|41|84|69|65|74|66|
^ Start of Segment data
20 | |4D|80|84|69|65|74|66|57|41|84|69|65|74|66|
^ MuxingApp start
In the above example, the Element ID of the Segment Element is stored
at offset 16, the Element Data Size of the Segment Element is stored
at offset 20, and the Element Data of the Segment Element is stored
at offset 21.
The MuxingApp Element is stored at offset 26. Since the Segment
Position of an Element is calculated by subtracting the position of
the Element Data of the containing Segment Element from the position
of that Element, the Segment Position of the MuxingApp Element in the
above example is "26 - 21" or "5".
17. Linked Segments
Matroska provides several methods to link two or more Segment
Elements together to create a Linked Segment. A Linked Segment is a
set of multiple Segments linked together into a single presentation
by using Hard Linking or Medium Linking.
All Segments within a Linked Segment MUST have a SegmentUUID.
All Segments within a Linked Segment SHOULD be stored within the same
directory or be quickly accessible based on their SegmentUUID in
order to have a seamless transition between Segments.
All Segments within a Linked Segment MAY set a SegmentFamily with a
common value to make it easier for a Matroska Player to know which
Segments are meant to be played together.
The SegmentFilename, PrevFilename, and NextFilename elements MAY also
give hints on the original filenames that were used when the Segment
links were created in case some SegmentUUIDs are damaged.
17.1. Hard Linking
Hard Linking, also called splitting, is the process of creating a
Linked Segment by linking multiple Segment Elements using the
NextUUID and PrevUUID Elements.
All Segments within a Hard-Linked Segment MUST use the same Tracks
list and TimestampScale.
Within a Linked Segment, the timestamps of Block and SimpleBlock MUST
consecutively follow the timestamps of Block and SimpleBlock from the
previous Segment in linking order.
With Hard Linking, the chapters of any Segment within the Linked
Segment MUST only reference the current Segment. The NextUUID and
PrevUUID reference the respective SegmentUUID values of the next and
previous Segments.
The first Segment of a Linked Segment MUST NOT have a PrevUUID
Element. The last Segment of a Linked Segment MUST NOT have a
NextUUID Element.
For each node of the chain of Segments of a Linked Segment, at least
one Segment MUST reference the other Segment within the chain.
In a chain of Segments of a Linked Segment, the NextUUID always takes
precedence over the PrevUUID. If SegmentA has a NextUUID to SegmentB
and SegmentB has a PrevUUID to SegmentC, the link to use is NextUUID
between SegmentA and SegmentB; SegmentC is not part of the Linked
Segment.
If SegmentB has a PrevUUID to SegmentA, but SegmentA has no NextUUID,
then the Matroska Player MAY consider these two Segments linked as
SegmentA followed by SegmentB.
As an example, three Segments can be Hard Linked as a Linked Segment
through cross-referencing each other with SegmentUUID, PrevUUID, and
NextUUID as shown in Table 41:
+==========+================+==================+==================+
|file name |SegmentUUID | PrevUUID | NextUUID |
+==========+================+==================+==================+
|start.mkv |71000c23cd310998| Invalid | a77b3598941cb803 |
| |53fbc94dd984a5dd| | eac0fcdafe44fac9 |
+----------+----------------+------------------+------------------+
|middle.mkv|a77b3598941cb803| 71000c23cd310998 | 6c92285fa6d3e827 |
| |eac0fcdafe44fac9| 53fbc94dd984a5dd | b198d120ea3ac674 |
+----------+----------------+------------------+------------------+
|end.mkv |6c92285fa6d3e827| a77b3598941cb803 | Invalid |
| |b198d120ea3ac674| eac0fcdafe44fac9 | |
+----------+----------------+------------------+------------------+
Table 41: Usual Hard-Linking UIDs
An example where only the NextUUID Element is used:
+============+==================+==========+==================+
| file name | SegmentUUID | PrevUUID | NextUUID |
+============+==================+==========+==================+
| start.mkv | 71000c23cd310998 | Invalid | a77b3598941cb803 |
| | 53fbc94dd984a5dd | | eac0fcdafe44fac9 |
+------------+------------------+----------+------------------+
| middle.mkv | a77b3598941cb803 | n/a | 6c92285fa6d3e827 |
| | eac0fcdafe44fac9 | | b198d120ea3ac674 |
+------------+------------------+----------+------------------+
| end.mkv | 6c92285fa6d3e827 | n/a | Invalid |
| | b198d120ea3ac674 | | |
+------------+------------------+----------+------------------+
Table 42: Hard Linking without PrevUUID
An example where only the PrevUUID Element is used:
+============+==================+==================+==========+
| file name | SegmentUUID | PrevUUID | NextUUID |
+============+==================+==================+==========+
| start.mkv | 71000c23cd310998 | Invalid | n/a |
| | 53fbc94dd984a5dd | | |
+------------+------------------+------------------+----------+
| middle.mkv | a77b3598941cb803 | 71000c23cd310998 | n/a |
| | eac0fcdafe44fac9 | 53fbc94dd984a5dd | |
+------------+------------------+------------------+----------+
| end.mkv | 6c92285fa6d3e827 | a77b3598941cb803 | Invalid |
| | b198d120ea3ac674 | eac0fcdafe44fac9 | |
+------------+------------------+------------------+----------+
Table 43: Hard Linking without NextUUID
An example where only the middle.mkv is using the PrevUUID and
NextUUID Elements:
+==========+================+==================+==================+
|file name |SegmentUUID | PrevUUID | NextUUID |
+==========+================+==================+==================+
|start.mkv |71000c23cd310998| Invalid | n/a |
| |53fbc94dd984a5dd| | |
+----------+----------------+------------------+------------------+
|middle.mkv|a77b3598941cb803| 71000c23cd310998 | 6c92285fa6d3e827 |
| |eac0fcdafe44fac9| 53fbc94dd984a5dd | b198d120ea3ac674 |
+----------+----------------+------------------+------------------+
|end.mkv |6c92285fa6d3e827| n/a | Invalid |
| |b198d120ea3ac674| | |
+----------+----------------+------------------+------------------+
Table 44: Hard Linking with Mixed UID Links
17.2. Medium Linking
Medium Linking creates relationships between Segments using Ordered
Chapters (Section 20.1.3) and the ChapterSegmentUUID Element. A
Chapter Edition with Ordered Chapters MAY contain Chapter elements
that reference timestamp ranges from other Segments. The Segment
referenced by the Ordered Chapter via the ChapterSegmentUUID Element
SHOULD be played as part of a Linked Segment.
The timestamps of Segment content referenced by Ordered Chapters MUST
be adjusted according to the cumulative duration of the previous
Ordered Chapters.
As an example, a file named intro.mkv could have a SegmentUUID of
"0xb16a58609fc7e60653a60c984fc11ead". Another file called
program.mkv could use a Chapter Edition that contains two Ordered
Chapters. The first chapter references the Segment of intro.mkv with
the use of a ChapterSegmentUUID, ChapterSegmentEditionUID,
ChapterTimeStart, and an optional ChapterTimeEnd element. The second
chapter references content within the Segment of program.mkv. A
Matroska Player SHOULD recognize the Linked Segment created by the
use of ChapterSegmentUUID in an enabled Edition and present the
reference content of the two Segments as a single presentation.
The ChapterSegmentUUID represents the Segment that holds the content
to play in place of the Linked Chapter. The ChapterSegmentUUID MUST
NOT be the SegmentUUID of its own Segment.
There are two ways to use a chapter link:
* Linked-Duration linking,
* Linked-Edition linking
17.2.1. Linked Duration
A Matroska Player MUST play the content of the linked Segment from
the ChapterTimeStart until the ChapterTimeEnd timestamp in place of
the Linked Chapter.
ChapterTimeStart and ChapterTimeEnd represent timestamps in the
Linked Segment matching the value of ChapterSegmentUUID. Their
values MUST be in the range of the linked Segment duration.
The ChapterTimeEnd value MUST be set when using Linked-Duration
chapter linking. ChapterSegmentEditionUID MUST NOT be set.
17.2.2. Linked Edition
A Matroska Player MUST play the whole Linked Edition of the linked
Segment in place of the Linked Chapter.
ChapterSegmentEditionUID represents a valid Edition from the Linked
Segment matching the value of ChapterSegmentUUID.
When using Linked-Edition chapter linking, ChapterTimeEnd is
OPTIONAL.
18. Track Flags
18.1. Default Flag
The "Default Track flag" is a hint for a Matroska Player indicating
that a given track SHOULD be eligible to be automatically selected as
the default track for a given language. If no tracks in a given
language have the Default Track flag set, then all tracks in that
language are eligible for automatic selection. This can be used to
indicate that a track provides "regular service" that is suitable for
users with default settings as opposed to specialized services, such
as commentary, hearing-impaired captions, or descriptive audio.
The Matroska Player MAY override the Default Track flag for any
reason, including user preferences to prefer tracks providing
accessibility services.
18.2. Forced Flag
The "Forced flag" tells the Matroska Player that it SHOULD display
this subtitle track, even if user preferences usually would not call
for any subtitles to be displayed alongside the audio track that is
currently selected. This can be used to indicate that a track
contains translations of onscreen text or dialogue spoken in a
different language than the track's primary language.
18.3. Hearing-Impaired Flag
The "Hearing-impaired flag" tells the Matroska Player that it SHOULD
prefer this track when selecting a default track for a hearing-
impaired user and that it MAY prefer to select a different track when
selecting a default track for a user that is not hearing-impaired.
18.4. Visually Impaired Flag
The "Visually Impaired flag" tells the Matroska Player that it SHOULD
prefer this track when selecting a default track for a visually
impaired user and that it MAY prefer to select a different track when
selecting a default track for a user that is not visually impaired.
18.5. Descriptions Flag
The "Descriptions flag" tells the Matroska Player that this track is
suitable to play via a text-to-speech system for a visually impaired
user and that it SHOULD NOT automatically select this track when
selecting a default track for a user that is not visually impaired.
18.6. Original Flag
The "Original flag" tells the Matroska Player that this track is in
the original language and that it SHOULD prefer the original language
if it's configured to prefer original-language tracks of this track's
type.
18.7. Commentary Flag
The "Commentary flag" tells the Matroska Player that this track
contains commentary on the content.
18.8. Track Operation
TrackOperation allows for the combination of multiple tracks to make
a virtual one. It uses two separate system to combine tracks. One
to create a 3D "composition" (left / right / background planes) and
one to simplify join two tracks together to make a single track.
A track created with TrackOperation is a proper track with a UID and
all its flags. However, the codec ID is meaningless because each
"sub" track needs to be decoded by its own decoder before the
"operation" is applied. The Cues Elements corresponding to such a
virtual track SHOULD be the union of the Cues Elements for each of
the tracks it's composed of (when the Cues are defined per track).
In the case of TrackJoinBlocks, the Block Elements (from BlockGroup
and SimpleBlock) of all the tracks SHOULD be used as if they were
defined for this new virtual Track. When two Block Elements have
overlapping start or end timestamps, it's up to the underlying system
to either drop some of these frames or render them the way they
overlap. This situation SHOULD be avoided when creating such tracks,
as you can never be sure of the end result on different platforms.
18.9. Overlay Track
Overlay tracks SHOULD be rendered in the same channel as the track
it's linked to. When content is found in such a track, it SHOULD be
played on the rendering channel instead of the original track.
18.10. Multi-planar and 3D Videos
There are two different ways to compress 3D videos: have each eye
track in a separate track and have one track have both eyes combined
inside (which is more efficient compression-wise). Matroska supports
both ways.
For the single track variant, there is the StereoMode Element, which
defines how planes are assembled in the track (mono or left-right
combined). Odd values of StereoMode means the left plane comes first
for more convenient reading. The pixel count of the track
(PixelWidth/PixelHeight) is the raw amount of pixels, e.g., 3840x1080
for full HD side by side and the DisplayWidth/DisplayHeight in pixels
is the amount of pixels for one plane (1920x1080 for that full HD
stream). Old stereo 3D were displayed using anaglyph (cyan and red
colors separated). For compatibility with such movies, there is a
value of the StereoMode that corresponds to AnaGlyph.
There is also a "packed" mode (values 13 and 14) that consists of
packing two frames together in a Block that uses lacing. The first
frame is the left eye and the other frame is the right eye (or vice
versa). The frames SHOULD be decoded in that order and are possibly
dependent on each other (P and B frames).
For separate tracks, Matroska needs to define exactly which track
does what. TrackOperation with TrackCombinePlanes does that. For
more details, see Section 18.8 to view how TrackOperation works.
The 3D support is still in infancy and may evolve to support more
features.
The StereoMode used to be part of Matroska v2, but it didn't meet the
requirement for multiple tracks. There was also a bug in libmatroska
prior to 0.9.0 that would save/read it as 0x53B9 instead of 0x53B8;
see OldStereoMode (Section 5.1.4.1.28.5). Matroska Readers MAY
support these legacy files by checking Matroska v2 or 0x53B9. The
older values of StereoMode were 0: mono, 1: right eye, 2: left eye,
and 3: both eyes; these are the only values that can be found in
OldStereoMode. They are not compatible with the StereoMode values
found in Matroska v3 and above.
19. Default Track Selection
This section provides some example sets of Tracks and hypothetical
user settings, along with indications of which Tracks that a
similarly-configured Matroska Player SHOULD automatically select for
playback by default in such a situation. A player MAY provide
additional settings with more detailed controls for more nuanced
scenarios. These examples are provided as guidelines to illustrate
the intended usages of the various supported Track flags and their
expected behaviors.
Track names are shown in English for illustrative purposes; actual
files may have titles in the language of each track or provide titles
in multiple languages.
19.1. Audio Selection
Example track set:
+===+=====+====+======+========+=======+=============+=============+
|No.|Type |Lang|Layout|Original|Default| Other Flags | Name |
+===+=====+====+======+========+=======+=============+=============+
|1 |Video|und |N/A |N/A |N/A | None | |
+---+-----+----+------+--------+-------+-------------+-------------+
|2 |Audio|eng |5.1 |1 |1 | None | |
+---+-----+----+------+--------+-------+-------------+-------------+
|3 |Audio|eng |2.0 |1 |1 | None | |
+---+-----+----+------+--------+-------+-------------+-------------+
|4 |Audio|eng |2.0 |1 |0 | Visually | Descriptive |
| | | | | | | Impaired | audio |
+---+-----+----+------+--------+-------+-------------+-------------+
|5 |Audio|esp |5.1 |0 |1 | None | |
+---+-----+----+------+--------+-------+-------------+-------------+
|6 |Audio|esp |2.0 |0 |0 | Visually | Descriptive |
| | | | | | | Impaired | audio |
+---+-----+----+------+--------+-------+-------------+-------------+
|7 |Audio|eng |2.0 |1 |0 | Commentary | Director's |
| | | | | | | | Commentary |
+---+-----+----+------+--------+-------+-------------+-------------+
|8 |Audio|eng |2.0 |1 |0 | None | Karaoke |
+---+-----+----+------+--------+-------+-------------+-------------+
Table 45: Audio Tracks for Default Selection
The table above shows a file with 7 audio tracks, 5 of which are in
English and 2 are in Spanish.
The English tracks all have the Original flag indicating that English
is the original content language.
Generally, the player will first consider the track languages. If
the player has an option to prefer original-language audio and the
user has enabled it, then it should prefer one of the tracks that
have the Original flag. If configured to specifically prefer audio
tracks in English or Spanish, the player should select one of the
tracks in the corresponding language. The player may also wish to
prefer a track with the Original flag if no tracks matching any of
the user's explicitly-preferred languages are available.
Two of the tracks have the Visually Impaired flag. If the player has
been configured to prefer such tracks, it should select one;
otherwise, it should avoid them if possible.
If selecting an English track, when other settings have left multiple
possible options, it may be useful to exclude the tracks that lack
the Default flag. Here, one provides descriptive service for the
visually impaired (which has its own flag and may be automatically
selected by user configuration, but is unsuitable for users with
default-configured players), one is a commentary track (which has its
own flag and the player may or may not have specialized handling
for), and the last option contains karaoke versions of the music that
plays during the film (which is an unusual specialized audio service
that Matroska has no built-in support for indicating, so it's
indicated in the track name instead). By not setting the Default
flag on these specialized tracks, the file's author hints that they
should not be automatically selected by a default-configured player.
Having narrowed its choices down, the example player now may have to
select between tracks 2 and 3. The only difference between these
tracks is their channel layouts. 2 is 5.1 surround while 3 is stereo.
If the player is aware that the output device is a pair of headphones
or stereo speakers, it may wish to prefer the stereo mix
automatically. On the other hand, if it knows that the device is a
surround system, it may wish to prefer the surround mix.
If the player finishes analyzing all of the available audio tracks
and finds that multiple seem equally and maximally preferable, it
SHOULD default to the first of the group.
19.2. Subtitle Selection
Example track set:
+===+===========+====+========+=======+======+==========+==========+
|No.| Type |Lang|Original|Default|Forced| Other | Name |
| | | | | | | flags | |
+===+===========+====+========+=======+======+==========+==========+
|1 | Video |und |N/A |N/A |N/A | None | |
+---+-----------+----+--------+-------+------+----------+----------+
|2 | Audio |fra |1 |1 |N/A | None | |
+---+-----------+----+--------+-------+------+----------+----------+
|3 | Audio |por |0 |1 |N/A | None | |
+---+-----------+----+--------+-------+------+----------+----------+
|4 | Subtitles |fra |1 |1 |0 | None | |
+---+-----------+----+--------+-------+------+----------+----------+
|5 | Subtitles |fra |1 |0 |0 | Hearing- | Captions |
| | | | | | | impaired | for the |
| | | | | | | | hearing- |
| | | | | | | | impaired |
+---+-----------+----+--------+-------+------+----------+----------+
|6 | Subtitles |por |0 |1 |0 | None | |
+---+-----------+----+--------+-------+------+----------+----------+
|7 | Subtitles |por |0 |0 |1 | None | Signs |
+---+-----------+----+--------+-------+------+----------+----------+
|8 | Subtitles |por |0 |0 |0 | Hearing- | SDH |
| | | | | | | impaired | |
+---+-----------+----+--------+-------+------+----------+----------+
Table 46: Subtitle Tracks for Default Selection
The table above shows 2 audio tracks and 5 subtitle tracks. As we
can see, French is the original language.
We'll start by discussing the case where the user prefers French (or
original-language) audio (or has explicitly selected the French audio
track), and also prefers French subtitles.
In this case, if the player isn't configured to display captions when
the audio matches their preferred subtitle languages, the player
doesn't need to select a subtitle track at all.
If the user _has_ indicated that they want captions to be displayed,
the selection simply comes down to whether hearing-impaired subtitles
are preferred.
The situation for a user who prefers Portuguese subtitles starts out
somewhat analogous. If they select the original French audio (either
by explicit audio language preference, preference for original-
language tracks, or by explicitly selecting that track), then the
selection once again comes down to the hearing-impaired preference.
However, the case where the Portuguese audio track is selected has an
important catch: a Forced track in Portuguese is present. This may
contain translations of onscreen text from the video track or of
portions of the audio that are not translated (music, for instance).
This means that even if the user's preferences wouldn't normally call
for captions here, the Forced track should be selected nonetheless
rather than selecting no track at all. On the other hand, if the
user's preferences _do_ call for captions, the non-Forced tracks
should be preferred, as the Forced track will not contain captioning
for the dialogue.
20. Chapters
The Matroska Chapters system can have multiple Editions and each
Edition can consist of Simple Chapters where a chapter start time is
used as a marker in the timeline only. An Edition can be more
complex with Ordered Chapters where a chapter end time stamp is
additionally used or much more complex with Linked Chapters. The
Matroska Chapters system can also have a menu structure borrowed from
the DVD-menu system [DVD-Video] or have its own built-in Matroska
menu structure.
20.1. EditionEntry
The EditionEntry is also called an Edition. An Edition contains a
set of Edition flags and MUST contain at least one ChapterAtom
Element. Chapters are always inside an Edition (or a Chapter itself
is part of an Edition). Multiple Editions are allowed. Some of
these Editions MAY be ordered and others are not.
20.1.1. EditionFlagDefault
Only one Edition SHOULD have an EditionFlagDefault flag set to true.
20.1.2. Default Edition
The Default Edition is the Edition that a Matroska Player SHOULD use
for playback by default.
The first Edition with the EditionFlagDefault flag set to true is the
Default Edition.
When all EditionFlagDefault flags are set to false, then the first
Edition is the Default Edition.
+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | true | X |
+-----------+-------------+-----------------+
| Edition 2 | true | |
+-----------+-------------+-----------------+
| Edition 3 | true | |
+-----------+-------------+-----------------+
Table 47: Default Edition, All Default
+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | false | X |
+-----------+-------------+-----------------+
| Edition 2 | false | |
+-----------+-------------+-----------------+
| Edition 3 | false | |
+-----------+-------------+-----------------+
Table 48: Default Edition, No Default
+===========+=============+=================+
| Edition | FlagDefault | Default Edition |
+===========+=============+=================+
| Edition 1 | false | |
+-----------+-------------+-----------------+
| Edition 2 | true | X |
+-----------+-------------+-----------------+
| Edition 3 | false | |
+-----------+-------------+-----------------+
Table 49: Default Edition, With Default
20.1.3. EditionFlagOrdered
The EditionFlagOrdered Flag is a significant feature, as it enables
an Edition of Ordered Chapters that define and arrange a virtual
timeline rather than simply labeling points within the timeline. For
example, with Editions of Ordered Chapters, a single Matroska file
can present multiple edits of a film without duplicating content.
Alternatively, if a videotape is digitized in full, one Ordered
Edition could present the full content (including colorbars,
countdown, slate, a feature presentation, and black frames) while
another Edition of Ordered Chapters can use Chapters that only mark
the intended presentation with the colorbars and other ancillary
visual information excluded. If an Edition of Ordered Chapters is
enabled, then the Matroska Player MUST play those Chapters in their
stored order from the timestamp marked in the ChapterTimeStart
Element to the timestamp marked in to ChapterTimeEnd Element.
If the EditionFlagOrdered Flag evaluates to "0", Simple Chapters are
used and only the ChapterTimeStart of a Chapter is used as a chapter
mark to jump to the predefined point in the timeline. With Simple
Chapters, a Matroska Player MUST ignore certain Chapter Elements. In
that case, these elements are informational only.
The following list shows the different Chapter elements only found in
Ordered Chapters.
* ChapterAtom/ChapterSegmentUUID
* ChapterAtom/ChapterSegmentEditionUID
* ChapterAtom/ChapterTrack
* ChapterAtom/ChapProcess
* Info/ChapterTranslate
* TrackEntry/TrackTranslate
Furthermore, there are other EBML Elements that could be used if the
EditionFlagOrdered evaluates to "1".
20.1.3.1. Ordered-Edition and Matroska Segment Linking
Hard Linking: Ordered Chapters supersede the Hard Linking.
Medium Linking: Ordered Chapters are used in a normal way and can be
combined with the ChapterSegmentUUID element, which establishes a
link to another Segment.
See Section 17 on the Linked Segments for more information about Hard
Linking and Medium Linking.
20.2. ChapterAtom
The ChapterAtom is also called a Chapter.
20.2.1. ChapterTimeStart
ChapterTimeStart is the timestamp of the start of Chapter with
nanosecond accuracy and is not scaled by TimestampScale. For Simple
Chapters, this is the position of the chapter markers in the
timeline.
20.2.2. ChapterTimeEnd
ChapterTimeEnd is the timestamp of the end of Chapter with nanosecond
accuracy and is not scaled by TimestampScale. The timestamp defined
by the ChapterTimeEnd is not part of the Chapter. A Matroska Player
calculates the duration of this Chapter by using the difference
between the ChapterTimeEnd and ChapterTimeStart. The end timestamp
MUST be greater than or equal to the start timestamp.
When the ChapterTimeEnd timestamp is equal to the ChapterTimeStart
timestamp, the timestamps is included in the Chapter. It can be
useful to put markers in a file or add chapter commands with ordered
chapter commands without having to play anything; see
Section 5.1.7.1.4.14.
+===========+=================+===============+===============+
| Chapter | Start timestamp | End timestamp | Duration |
+===========+=================+===============+===============+
| Chapter 1 | 0 | 1000000000 | 1000000000 |
+-----------+-----------------+---------------+---------------+
| Chapter 2 | 1000000000 | 5000000000 | 4000000000 |
+-----------+-----------------+---------------+---------------+
| Chapter 3 | 6000000000 | 6000000000 | 0 |
+-----------+-----------------+---------------+---------------+
| Chapter 4 | 9000000000 | 8000000000 | Invalid |
| | | | (-1000000000) |
+-----------+-----------------+---------------+---------------+
Table 50: ChapterTimeEnd Usage Possibilities
20.2.3. Nested Chapters
A ChapterAtom element can contain other ChapterAtom elements. That
element is a Parent Chapter and the ChapterAtom elements it contains
are Nested Chapters.
Nested Chapters can be useful to tag small parts of a Segment that
already has tags or add Chapter Codec commands on smaller parts of a
Segment that already has Chapter Codec commands.
The ChapterTimeStart of a Nested Chapter MUST be greater than or
equal to the ChapterTimeStart of its Parent Chapter.
If the Parent Chapter of a Nested Chapter has a ChapterTimeEnd, the
ChapterTimeStart of that Nested Chapter MUST be smaller than or equal
to the ChapterTimeEnd of the Parent Chapter.
20.2.4. Nested Chapters in Ordered Chapters
The ChapterTimeEnd of the lowest level of Nested Chapters MUST be set
for Ordered Chapters.
When used with Ordered Chapters, the ChapterTimeEnd value of a Parent
Chapter is useless for playback, as the proper playback sections are
described in its Nested Chapters. The ChapterTimeEnd SHOULD NOT be
set in Parent Chapters and MUST be ignored for playback.
20.2.5. ChapterFlagHidden
Each Chapter within a ChapterFlagHidden flag works independently of
Parent Chapters. A Nested Chapter with a ChapterFlagHidden flag that
evaluates to "0" remains visible in the user interface even if the
Parent Chapter ChapterFlagHidden flag is set to "1".
+==========================+===================+=========+
| Chapter + Nested Chapter | ChapterFlagHidden | visible |
+==========================+===================+=========+
| Chapter 1 | 0 | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 1.1 | 0 | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 1.2 | 1 | no |
+--------------------------+-------------------+---------+
| Chapter 2 | 1 | no |
+--------------------------+-------------------+---------+
| Nested Chapter 2.1 | 0 | yes |
+--------------------------+-------------------+---------+
| Nested Chapter 2.2 | 1 | no |
+--------------------------+-------------------+---------+
Table 51: ChapterFlagHidden Nested Visibility
20.3. Menu Features
The menu features are handled like a chapter codec. That means each
codec has a type, some private data, and some data in the chapters.
The type of the menu system is defined by the ChapProcessCodecID
parameter. For now, only two values are supported: 0 Matroska
Script, 1 menu borrowed from the DVD [DVD-Video]. The private data
depends on the type of menu system (stored in ChapProcessPrivate),
which is the same for the data in the chapters (stored in
ChapProcessData).
The menu system, as well as Chapter Codecs in general, can perform
actions on the Matroska Player, such as jumping to another Chapter or
Edition, selecting different tracks, and possibly more. The scope of
all the possibilities of Chapter Codecs is not covered in this
document, as it depends on the Chapter Codec features and its
integration in a Matroska Player.
20.4. Physical Types
Each level can have different meanings for audio and video. The
ORIGINAL_MEDIA_TYPE tag [MatroskaTags] can be used to specify a
string for ChapterPhysicalEquiv = 60. Here is the list of possible
levels for both audio and video:
+=======+=======================+=============+=====================+
| Value | Audio | Video | Comment |
+=======+=======================+=============+=====================+
| 70 | SET / PACKAGE | SET / | The collection of |
| | | PACKAGE | different media. |
+-------+-----------------------+-------------+---------------------+
| 60 | CD / 12" / 10" / 7" / | DVD / VHS | The physical |
| | TAPE / MINIDISC / DAT | / | medium, such as a |
| | | LASERDISC | CD or a DVD. |
+-------+-----------------------+-------------+---------------------+
| 50 | SIDE | SIDE | When the original |
| | | | medium (LP/DVD) has |
| | | | different sides. |
+-------+-----------------------+-------------+---------------------+
| 40 | - | LAYER | Another physical |
| | | | level on DVDs. |
+-------+-----------------------+-------------+---------------------+
| 30 | SESSION | SESSION | As found on CDs and |
| | | | DVDs. |
+-------+-----------------------+-------------+---------------------+
| 20 | TRACK | - | As found on CDs. |
+-------+-----------------------+-------------+---------------------+
| 10 | INDEX | - | The first logical |
| | | | level of the side/ |
| | | | medium. |
+-------+-----------------------+-------------+---------------------+
Table 52: ChapterPhysicalEquiv Meaning per Track Type
20.5. Chapter Examples
20.5.1. Example 1: Basic Chaptering
In this example, a movie is split in different chapters. It could
also just be an audio file (album) in which each track corresponds to
a chapter.
* 00000 ms - 05000 ms: Intro
* 05000 ms - 25000 ms: Before the crime
* 25000 ms - 27500 ms: The crime
* 27500 ms - 38000 ms: The killer is arrested
* 38000 ms - 43000 ms: Credits
This would translate in the following Matroska form, with the EBML
tree shown as XML:
16603393396715046047
1193046
0
5000000000
Intro
2311527
5000000000
25000000000
Before the crime
Avant le crime
fra
3430008
25000000000
27500000000
The crime
Le crime
fra
4548489
27500000000
38000000000
After the crime
Apres le crime
fra
5666960
38000000000
43000000000
Credits
Generique
fra
Figure 16: Basic Chapters Example
20.5.2. Example 2: Nested Chapters
In this example, an (existing) album is split into different chapters
and one of them contains another splitting.
20.5.2.1. The Micronauts "Bleep To Bleep"
* 00:00 - 12:28: Baby wants to Bleep/Rock
- 00:00 - 04:38: Baby wants to bleep (pt.1)
- 04:38 - 07:12: Baby wants to rock
- 07:12 - 10:33: Baby wants to bleep (pt.2)
- 10:33 - 12:28: Baby wants to bleep (pt.3)
* 12:30 - 19:38: Bleeper_O+2
* 19:40 - 22:20: Baby wants to bleep (pt.4)
* 22:22 - 25:18: Bleep to bleep
* 25:20 - 33:35: Baby wants to bleep (k)
* 33:37 - 44:28: Bleeper
This would translate in the following Matroska form, with the EBML
tree shown as XML:
1281690858003401414
1
0
748000000
Baby wants to Bleep/Rock
2
0
278000000
Baby wants to bleep (pt.1)
3
278000000
432000000
Baby wants to rock
4
432000000
633000000
Baby wants to bleep (pt.2)
5
633000000
748000000
Baby wants to bleep (pt.3)
6
750000000
1178500000
Bleeper_O+2
7
1180500000
1340000000
Baby wants to bleep (pt.4)
8
1342000000
1518000000
Bleep to bleep
9
1520000000
2015000000
Baby wants to bleep (k)
10
2017000000
2668000000
Bleeper
Figure 17: Nested Chapters Example
21. Attachments
Matroska supports storage of related files and data in the
Attachments Element (a Top-Level Element). Attachment Elements can
be used to store related cover art, font files, transcripts, reports,
error recovery files, picture or text-based annotations, copies of
specifications, or other ancillary files related to the Segment.
Matroska Readers MUST NOT execute files stored as Attachment
Elements.
21.1. Cover Art
This section defines a set of guidelines for the storage of cover art
in Matroska files. A Matroska Reader MAY use embedded cover art to
display a representational still-image depiction of the multimedia
contents of the Matroska file.
Only [JPEG] and PNG [RFC2083] image formats SHOULD be used for cover
art pictures.
There can be two different covers for a movie/album: a portrait style
(e.g., a DVD case) and a landscape style (e.g., a wide banner ad).
There can be two versions of the same cover: the normal cover and the
small cover. The dimension of the normal cover SHOULD be 600 pixels
on the smallest side (e.g., 960x600 for landscape, 600x800 for
portrait, or 600x600 for square). The dimension of the small cover
SHOULD be 120 pixels on the smallest side (e.g., 192x120 or 120x160).
Versions of cover art can be differentiated by the filename that is
stored in the FileName Element. The default filename of the normal
cover in square or portrait mode is cover.(jpg|png). When stored,
the normal cover SHOULD be the first Attachment in storage order.
The small cover SHOULD be prefixed with "small_", such as
small_cover.(jpg|png). The landscape variant SHOULD be suffixed with
"_land", such as cover_land.(jpg|png). The filenames are case-
sensitive.
The following table provides examples of file names for cover art in
Attachments.
+======================+===================+=================+
| FileName | Image Orientation | Pixel Length of |
| | | Smallest Side |
+======================+===================+=================+
| cover.jpg | Portrait or | 600 |
| | square | |
+----------------------+-------------------+-----------------+
| small_cover.png | Portrait or | 120 |
| | square | |
+----------------------+-------------------+-----------------+
| cover_land.png | Landscape | 600 |
+----------------------+-------------------+-----------------+
| small_cover_land.jpg | Landscape | 120 |
+----------------------+-------------------+-----------------+
Table 53: Cover Art Filenames
21.2. Font Files
Font files MAY be added to a Matroska file as Attachments so that the
font file may be used to display an associated subtitle track. This
allows the presentation of a Matroska file to be consistent in
various environments where the needed fonts might not be available on
the local system.
Depending on the font format in question, each font file can contain
multiple font variants. Each font variant has a name that will be
referred to as Font Name from now on. This Font Name can be
different from the Attachment's FileName, even when disregarding the
extension. In order to select a font for display, a Matroska player
SHOULD consider both the Font Name and the base name of the
Attachment's FileName, preferring the former when there are multiple
matches.
Subtitle codecs, such as SubStation Alpha (SSA/ASS), usually refer to
a font by its Font Name and instead of its filename. If none of the
Attachments are a match for the Font Name, the Matroska player SHOULD
attempt to find a system font whose Font Name matches the one used in
the subtitle track.
Since loading fonts temporarily can take a while, a Matroska player
usually loads or installs all the fonts found in attachments so they
are ready to be used during playback. Failure to use the font
attachment might result in incorrect rendering of the subtitles.
If a selected subtitle track has some AttachmentLink elements, the
player MAY restrict its font rendering to use only these fonts.
A Matroska player SHOULD handle the official font media types from
[RFC8081] when the system can handle the type:
font/sfnt: Generic SFNT Font Type
font/ttf: TrueType Font (TTF) Font Type
font/otf: OpenType Layout (OTF) Font Type
font/collection: Collection Font Type
font/woff: WOFF 1.0
font/woff2: WOFF 2.0
Fonts in Matroska existed long before [RFC8081]. A few unofficial
media types for fonts were used in existing files. Therefore, it is
RECOMMENDED for a Matroska player to support the following legacy
media types for font attachments:
application/x-truetype-font: TTFs equivalent to font/ttf and
sometimes font/otf.
application/x-font-ttf: TTFs, equivalent to font/ttf.
application/vnd.ms-opentype: OTF fonts, equivalent to font/otf
application/font-sfnt: Generic SFNT Font Type, equivalent to font/
sfnt
application/font-woff: WOFF 1.0, equivalent to font/woff
There may also be some font attachments with the application/octet-
stream media type. In that case, the Matroska player MAY try to
guess the font type by checking the file extension of the
AttachedFile\FileName string. Common file extensions for fonts are:
* .ttf for TTFs, equivalent to font/ttf;
* .otf for OTF fonts, equivalent to font/otf; and
* .ttc for Collection fonts, equivalent to font/collection.
The file extension check MUST be case-insensitive.
Matroska Writers SHOULD use a valid font media type from [RFC8081] in
the AttachedFile\FileMediaType of the font attachment. They MAY use
the media types found in older files when compatibility with older
players is necessary.
22. Cues
The Cues Element provides an index of certain Cluster Elements to
allow for optimized seeking to absolute timestamps within the
Segment. The Cues Element contains one or many CuePoint Elements,
and each MUST reference an absolute timestamp (via the CueTime
Element), a Track (via the CueTrack Element), and a Segment Position
(via the CueClusterPosition Element). Additional non-mandated
Elements are part of the CuePoint Element, such as CueDuration,
CueRelativePosition, CueCodecState, and others that provide any
Matroska Reader with additional information to use in the
optimization of seeking performance.
22.1. Recommendations
The following recommendations are provided to optimize Matroska
performance.
* Unless Matroska is used as a live stream, it SHOULD contain a Cues
Element.
* For each video track, each keyframe SHOULD be referenced by a
CuePoint Element.
* It is RECOMMENDED to not reference non-keyframes of video tracks
in Cues unless it references a Cluster Element that contains a
CodecState Element, but no keyframes.
* For each subtitle track present, each subtitle frame SHOULD be
referenced by a CuePoint Element with a CueDuration Element.
* References to audio tracks MAY be skipped in CuePoint Elements if
a video track is present. When included, the CuePoint Elements
SHOULD reference audio keyframes once every 500 milliseconds at
most.
* If the referenced frame is not stored within the first SimpleBlock
or first BlockGroup within its Cluster Element, then the
CueRelativePosition Element SHOULD be written to reference where
in the Cluster the reference frame is stored.
* If a CuePoint Element references a Cluster Element that includes a
CodecState Element, then that CuePoint Element MUST use a
CueCodecState Element.
* CuePoint Elements SHOULD be numerically sorted in storage order by
the value of the CueTime Element.
23. Matroska Streaming
In Matroska, there are two kinds of streaming: file access and
livestreaming.
23.1. File Access
File access can simply be reading a file located on your computer,
but it also includes accessing a file from an HTTP (web) server or
Common Internet File System (CIFS) (Windows share) server. These
protocols are usually safe from reading errors and seeking in the
stream is possible. However, when a file is stored far away or on a
slow server, seeking can be an expensive operation and should be
avoided. The guidelines in Section 25, when followed, help reduce
the number of seeking operations for regular playback and also have
the playback start quickly without a lot of data needed to read first
(such as a Cues Element, Attachment Element, or SeekHead Element).
Matroska, having a small overhead, is well suited for storing music/
videos on file servers without a big impact on the bandwidth used.
Matroska does not require the index to be loaded before playing,
which allows playback to start very quickly. The index can be loaded
only when seeking is requested the first time.
23.2. Livestreaming
Livestreaming is the equivalent of television broadcasting on the
Internet. There are two families of servers for livestreaming: RTP /
Real-Time Streaming Protocol (RTSP) and HTTP. Matroska is not meant
to be used over RTP. RTP already has timing and channel mechanisms
that would be wasted if doubled in Matroska. Additionally, having
the same information at the RTP and Matroska level would be a source
of confusion if they do not match. Livestreaming of Matroska over
file-like protocols like HTTP, QUIC, etc., is possible.
A live Matroska stream is different from a file because it usually
has no known end (only ending when the client disconnects). For
this, all bits of the "size" portion of the Segment Element MUST be
set to 1. Another option is to concatenate Segment Elements with
known sizes one after the other. This solution allows a change of
codec/resolution between each Segment. For example, this allows for
a switch between 4:3 and 16:9 in a television program.
When Segment Elements are continuous, certain Elements like SeekHead,
Cues, Chapters, and Attachments MUST NOT be used.
It is possible for a Matroska Player to detect that a stream is not
seekable. If the stream has neither a SeekHead list nor a Cues list
at the beginning of the stream, it SHOULD be considered non-seekable.
Even though it is possible to seek forward in the stream, it is NOT
RECOMMENDED.
In the context of live radio or web TV, it is possible to "tag" the
content while it is playing. The Tags Element can be placed between
Clusters each time it is necessary. In that case, the new Tags
Element MUST reset the previously encountered Tags Elements and use
the new values instead.
24. Tags
24.1. Tags Precedence
Tags allow tagging all kinds of Matroska parts with very detailed
metadata in multiple languages.
Some Matroska elements also contain their own string value, such as
the Track Name (Section 5.1.4.1.18) or the Chapter String
(Section 5.1.7.1.4.10).
The following Matroska elements can also be defined with tags:
* The Track Name Element (Section 5.1.4.1.18) corresponds to a tag
with the TagTrackUID (Section 5.1.8.1.1.3) set to the given track,
a TagName of TITLE (Section 5.1.8.1.2.1), and a TagLanguage
(Section 5.1.8.1.2.2) or TagLanguageBCP47 (Section 5.1.8.1.2.3) of
"und".
* The Chapter String Element (Section 5.1.7.1.4.10) corresponds to a
tag with the TagChapterUID (Section 5.1.8.1.1.5) set to the same
chapter UID, a TagName of TITLE (Section 5.1.8.1.2.1), and a
TagLanguage (Section 5.1.8.1.2.2) or TagLanguageBCP47
(Section 5.1.8.1.2.3) matching the ChapLanguage
(Section 5.1.7.1.4.11) or ChapLanguageBCP47
(Section 5.1.7.1.4.12), respectively.
* The FileDescription Element (Section 5.1.6.1.1) of an attachment
corresponds to a tag with the TagAttachmentUID
(Section 5.1.8.1.1.6) set to the given attachment, a TagName of
TITLE (Section 5.1.8.1.2.1), and a TagLanguage
(Section 5.1.8.1.2.2) or TagLanguageBCP47 (Section 5.1.8.1.2.3) of
"und".
When both values exist in the file, the value found in Tags takes
precedence over the value found in original location of the element.
For example, if you have a TrackEntry\Name element and Tag TITLE for
that track in a Matroska Segment, the Tag string SHOULD be used
instead of the TrackEntry\Name string to identify the track.
As the Tag element is optional, a lot of Matroska Readers do not
handle it and will not use the tags value when it's found. For
maximum compatibility, it's usually better to put the strings in the
TrackEntry, ChapterAtom, and Attachment and keep the tags matching
these values if tags are also used.
24.2. Tag Levels
Tag elements allow tagging information on multiple levels; each level
has a TargetTypeValue Section 5.1.8.1.1.1. An element for a given
TargetTypeValue also applies to the lower levels denoted by smaller
TargetTypeValue values. If an upper value doesn't apply to a level,
but the actual value to use is not known, an empty TagString
element(Section 5.1.8.1.2.5) or an empty TagBinary element
(Section 5.1.8.1.2.6) MUST be used as the tag value for this level.
See [MatroskaTags] for more details on common tag names, types, and
descriptions.
25. Implementation Recommendations
25.1. Cluster
It is RECOMMENDED that each individual Cluster Element contains no
more than five seconds or five megabytes of content.
25.2. SeekHead
It is RECOMMENDED that the first SeekHead Element be followed by a
Void Element to allow for the SeekHead Element to be expanded to
cover new Top-Level Elements that could be added to the Matroska
file, such as Tags, Chapters, and Attachments Elements.
The size of this Void Element should be adjusted depending on the
Matroska file that already has Tags, Chapters, and Attachments
Elements.
25.3. Optimum Layouts
While there can be Top-Level Elements in any order, some ordering of
Elements are better than others. The following sections detail a few
optimum layouts for different use cases.
25.3.1. Optimum Layout for a Muxer
This is the basic layout muxers should be using for an efficient
playback experience:
* SeekHead
* Info
* Tracks
* Chapters
* Attachments
* Tags
* Clusters
* Cues
25.3.2. Optimum Layout after Editing Tags
When tags from the previous layout need to be extended, they are
moved to the end with the extra information. The location where the
old tags were located is voided.
* SeekHead
* Info
* Tracks
* Chapters
* Attachments
* Void
* Clusters
* Cues
* Tags
25.3.3. Optimum Layout with Cues at the Front
Cues are usually a big chunk of data referencing a lot of locations
in the file. Players that want to seek in the file need to seek to
the end of the file to access these locations. It is often better if
they are placed early in the file. On the other hand, that means
players that don't intend to seek will have to read/skip this data no
matter what.
Because the Cues reference locations further in the file, it's often
complicated to allocate the proper space for that element before all
the locations are known. Therefore, this layout is rarely used:
* SeekHead
* Info
* Tracks
* Chapters
* Attachments
* Tags
* Cues
* Clusters
25.3.4. Optimum Layout for Livestreaming
In Livestreaming (Section 23.2), only a few elements make sense. For
example, SeekHead and Cues are useless. All elements other than the
Clusters MUST be placed before the Clusters.
* Info
* Tracks
* Attachments (rare)
* Tags
* Clusters
26. Security Considerations
Matroska inherits security considerations from EBML.
Attacks on a Matroska Reader could include:
* Storage of an arbitrary and potentially executable data within an
Attachment Element. Matroska Readers that extract or use data
from Matroska Attachments SHOULD check that the data adheres to
expectations or not use the attachement.
* A Matroska Attachment with an inaccurate media type.
* Damage to the Encryption and Compression fields (Section 14) that
would result in bogus binary data interpreted by the decoder.
* Chapter Codecs running unwanted commands on the host system.
The same error handling done for EBML applies to Matroska files.
Particular error handling is not covered in this specification, as
this is depends on the goal of the Matroska Readers. It is up to the
decision of the Matroska Readers on how to handle the errors if they
are recoverable in their code or not. For example, if the checksum
of the \Segment\Tracks is invalid, some could decide to try to read
the data anyway, some will just reject the file, and most will not
even check it.
Matroska Reader implementations need to be robust against malicious
payloads; those that are related to denial of service are outlined in
Section 2.1 of [RFC4732].
Although rarer, the same may apply to a Matroska Writer. Malicious
stream data must not cause the Matroska Writer to misbehave, as this
might allow an attacker access to transcoding gateways.
As an audio and visual container format, a Matroska file or stream
will potentially encapsulate numerous byte streams created with a
variety of codecs. Implementers will need to consider the security
considerations of these encapsulated formats.
27. IANA Considerations
27.1. Matroska Element IDs Registry
This document creates a new IANA registry called the "Matroska
Element IDs" registry.
To register a new Element ID in this registry, one needs an Element
ID, a Change Controller (IETF or email of registrant), and an
optional reference to a document describing the Element ID.
Element IDs are encoded using the VINT mechanism described in
Section 4 of [RFC8794] and can be between one and five octets long.
Five-octet-long Element IDs are possible only if they are declared in
the EBML header.
Element IDs are described in Section 5 of [RFC8794] with [Err7189]
and [Err7191].
One-octet Matroska Element IDs are to be allocated according to the
"RFC Required" policy [RFC8126].
Two-octet Matroska Element IDs are to be allocated according to the
"Specification Required" policy [RFC8126].
Three-octet and four-octet Matroska Element IDs are to be allocated
according to the "First Come First Served" policy [RFC8126].
The allowed values in the Matroska Element IDs registry are similar
to the ones found in the EBML Element IDs registry defined in
Section 17.1 of [RFC8794].
EBML IDs defined for the EBML Header, as defined in Section 17.1 of
[RFC8794], MUST NOT be used as Matroska Element IDs.
Given the scarcity of the one-octet Element IDs, they should only be
created to save space for elements found many times in a file. For
example, within a BlockGroup or Chapters. The four-octet Element IDs
are mostly for synchronization of large elements. They should only
be used for such high level elements. Elements that are not expected
to be used often should use three-octet Element IDs.
Elements found in Appendix A have an assigned Matroska Element ID for
historical reasons. These elements are not in use and SHOULD NOT be
reused unless there is no other IDs available with the desired size.
Such IDs are considered as reclaimed to the IANA registry, as they
could be used for other things in the future.
Values of Matroska Element IDs found in this document are assigned as
initial values as follows:
+============+=============================+======================+
| Element ID | Element Name | Reference |
+============+=============================+======================+
| 0x80 | ChapterDisplay | Described in |
| | | Section 5.1.7.1.4.9 |
+------------+-----------------------------+----------------------+
| 0x83 | TrackType | Described in |
| | | Section 5.1.4.1.3 |
+------------+-----------------------------+----------------------+
| 0x85 | ChapString | Described in |
| | | Section 5.1.7.1.4.10 |
+------------+-----------------------------+----------------------+
| 0x86 | CodecID | Described in |
| | | Section 5.1.4.1.21 |
+------------+-----------------------------+----------------------+
| 0x88 | FlagDefault | Described in |
| | | Section 5.1.4.1.5 |
+------------+-----------------------------+----------------------+
| 0x8E | Slices | Reclaimed |
| | | (Appendix A.5) |
+------------+-----------------------------+----------------------+
| 0x91 | ChapterTimeStart | Described in |
| | | Section 5.1.7.1.4.3 |
+------------+-----------------------------+----------------------+
| 0x92 | ChapterTimeEnd | Described in |
| | | Section 5.1.7.1.4.4 |
+------------+-----------------------------+----------------------+
| 0x96 | CueRefTime | Described in |
| | | Section 5.1.5.1.2.8 |
+------------+-----------------------------+----------------------+
| 0x97 | CueRefCluster | Reclaimed |
| | | (Appendix A.37) |
+------------+-----------------------------+----------------------+
| 0x98 | ChapterFlagHidden | Described in |
| | | Section 5.1.7.1.4.5 |
+------------+-----------------------------+----------------------+
| 0x9A | FlagInterlaced | Described in |
| | | Section 5.1.4.1.28.1 |
+------------+-----------------------------+----------------------+
| 0x9B | BlockDuration | Described in |
| | | Section 5.1.3.5.3 |
+------------+-----------------------------+----------------------+
| 0x9C | FlagLacing | Described in |
| | | Section 5.1.4.1.12 |
+------------+-----------------------------+----------------------+
| 0x9D | FieldOrder | Described in |
| | | Section 5.1.4.1.28.2 |
+------------+-----------------------------+----------------------+
| 0x9F | Channels | Described in |
| | | Section 5.1.4.1.29.3 |
+------------+-----------------------------+----------------------+
| 0xA0 | BlockGroup | Described in |
| | | Section 5.1.3.5 |
+------------+-----------------------------+----------------------+
| 0xA1 | Block | Described in |
| | | Section 5.1.3.5.1 |
+------------+-----------------------------+----------------------+
| 0xA2 | BlockVirtual | Reclaimed |
| | | (Appendix A.3) |
+------------+-----------------------------+----------------------+
| 0xA3 | SimpleBlock | Described in |
| | | Section 5.1.3.4 |
+------------+-----------------------------+----------------------+
| 0xA4 | CodecState | Described in |
| | | Section 5.1.3.5.6 |
+------------+-----------------------------+----------------------+
| 0xA5 | BlockAdditional | Described in |
| | | Section 5.1.3.5.2.2 |
+------------+-----------------------------+----------------------+
| 0xA6 | BlockMore | Described in |
| | | Section 5.1.3.5.2.1 |
+------------+-----------------------------+----------------------+
| 0xA7 | Position | Described in |
| | | Section 5.1.3.2 |
+------------+-----------------------------+----------------------+
| 0xAA | CodecDecodeAll | Reclaimed |
| | | (Appendix A.22) |
+------------+-----------------------------+----------------------+
| 0xAB | PrevSize | Described in |
| | | Section 5.1.3.3 |
+------------+-----------------------------+----------------------+
| 0xAE | TrackEntry | Described in |
| | | Section 5.1.4.1 |
+------------+-----------------------------+----------------------+
| 0xAF | EncryptedBlock | Reclaimed |
| | | (Appendix A.15) |
+------------+-----------------------------+----------------------+
| 0xB0 | PixelWidth | Described in |
| | | Section 5.1.4.1.28.6 |
+------------+-----------------------------+----------------------+
| 0xB2 | CueDuration | Described in |
| | | Section 5.1.5.1.2.4 |
+------------+-----------------------------+----------------------+
| 0xB3 | CueTime | Described in |
| | | Section 5.1.5.1.1 |
+------------+-----------------------------+----------------------+
| 0xB5 | SamplingFrequency | Described in |
| | | Section 5.1.4.1.29.1 |
+------------+-----------------------------+----------------------+
| 0xB6 | ChapterAtom | Described in |
| | | Section 5.1.7.1.4 |
+------------+-----------------------------+----------------------+
| 0xB7 | CueTrackPositions | Described in |
| | | Section 5.1.5.1.2 |
+------------+-----------------------------+----------------------+
| 0xB9 | FlagEnabled | Described in |
| | | Section 5.1.4.1.4 |
+------------+-----------------------------+----------------------+
| 0xBA | PixelHeight | Described in |
| | | Section 5.1.4.1.28.7 |
+------------+-----------------------------+----------------------+
| 0xBB | CuePoint | Described in |
| | | Section 5.1.5.1 |
+------------+-----------------------------+----------------------+
| 0xC0 | TrickTrackUID | Reclaimed |
| | | (Appendix A.28) |
+------------+-----------------------------+----------------------+
| 0xC1 | TrickTrackSegmentUID | Reclaimed |
| | | (Appendix A.29) |
+------------+-----------------------------+----------------------+
| 0xC4 | TrickMasterTrackSegmentUID | Reclaimed |
| | | (Appendix A.32) |
+------------+-----------------------------+----------------------+
| 0xC6 | TrickTrackFlag | Reclaimed |
| | | (Appendix A.30) |
+------------+-----------------------------+----------------------+
| 0xC7 | TrickMasterTrackUID | Reclaimed |
| | | (Appendix A.31) |
+------------+-----------------------------+----------------------+
| 0xC8 | ReferenceFrame | Reclaimed |
| | | (Appendix A.12) |
+------------+-----------------------------+----------------------+
| 0xC9 | ReferenceOffset | Reclaimed |
| | | (Appendix A.13) |
+------------+-----------------------------+----------------------+
| 0xCA | ReferenceTimestamp | Reclaimed |
| | | (Appendix A.14) |
+------------+-----------------------------+----------------------+
| 0xCB | BlockAdditionID | Reclaimed |
| | | (Appendix A.9) |
+------------+-----------------------------+----------------------+
| 0xCC | LaceNumber | Reclaimed |
| | | (Appendix A.7) |
+------------+-----------------------------+----------------------+
| 0xCD | FrameNumber | Reclaimed |
| | | (Appendix A.8) |
+------------+-----------------------------+----------------------+
| 0xCE | Delay | Reclaimed |
| | | (Appendix A.10) |
+------------+-----------------------------+----------------------+
| 0xCF | SliceDuration | Reclaimed |
| | | (Appendix A.11) |
+------------+-----------------------------+----------------------+
| 0xD7 | TrackNumber | Described in |
| | | Section 5.1.4.1.1 |
+------------+-----------------------------+----------------------+
| 0xDB | CueReference | Described in |
| | | Section 5.1.5.1.2.7 |
+------------+-----------------------------+----------------------+
| 0xE0 | Video | Described in |
| | | Section 5.1.4.1.28 |
+------------+-----------------------------+----------------------+
| 0xE1 | Audio | Described in |
| | | Section 5.1.4.1.29 |
+------------+-----------------------------+----------------------+
| 0xE2 | TrackOperation | Described in |
| | | Section 5.1.4.1.30 |
+------------+-----------------------------+----------------------+
| 0xE3 | TrackCombinePlanes | Described in |
| | | Section 5.1.4.1.30.1 |
+------------+-----------------------------+----------------------+
| 0xE4 | TrackPlane | Described in |
| | | Section 5.1.4.1.30.2 |
+------------+-----------------------------+----------------------+
| 0xE5 | TrackPlaneUID | Described in |
| | | Section 5.1.4.1.30.3 |
+------------+-----------------------------+----------------------+
| 0xE6 | TrackPlaneType | Described in |
| | | Section 5.1.4.1.30.4 |
+------------+-----------------------------+----------------------+
| 0xE7 | Timestamp | Described in |
| | | Section 5.1.3.1 |
+------------+-----------------------------+----------------------+
| 0xE8 | TimeSlice | Reclaimed |
| | | (Appendix A.6) |
+------------+-----------------------------+----------------------+
| 0xE9 | TrackJoinBlocks | Described in |
| | | Section 5.1.4.1.30.5 |
+------------+-----------------------------+----------------------+
| 0xEA | CueCodecState | Described in |
| | | Section 5.1.5.1.2.6 |
+------------+-----------------------------+----------------------+
| 0xEB | CueRefCodecState | Reclaimed |
| | | (Appendix A.39) |
+------------+-----------------------------+----------------------+
| 0xED | TrackJoinUID | Described in |
| | | Section 5.1.4.1.30.6 |
+------------+-----------------------------+----------------------+
| 0xEE | BlockAddID | Described in |
| | | Section 5.1.3.5.2.3 |
+------------+-----------------------------+----------------------+
| 0xF0 | CueRelativePosition | Described in |
| | | Section 5.1.5.1.2.3 |
+------------+-----------------------------+----------------------+
| 0xF1 | CueClusterPosition | Described in |
| | | Section 5.1.5.1.2.2 |
+------------+-----------------------------+----------------------+
| 0xF7 | CueTrack | Described in |
| | | Section 5.1.5.1.2.1 |
+------------+-----------------------------+----------------------+
| 0xFA | ReferencePriority | Described in |
| | | Section 5.1.3.5.4 |
+------------+-----------------------------+----------------------+
| 0xFB | ReferenceBlock | Described in |
| | | Section 5.1.3.5.5 |
+------------+-----------------------------+----------------------+
| 0xFD | ReferenceVirtual | Reclaimed |
| | | (Appendix A.4) |
+------------+-----------------------------+----------------------+
| 0x41A4 | BlockAddIDName | Described in |
| | | Section 5.1.4.1.17.2 |
+------------+-----------------------------+----------------------+
| 0x41E4 | BlockAdditionMapping | Described in |
| | | Section 5.1.4.1.17 |
+------------+-----------------------------+----------------------+
| 0x41E7 | BlockAddIDType | Described in |
| | | Section 5.1.4.1.17.3 |
+------------+-----------------------------+----------------------+
| 0x41ED | BlockAddIDExtraData | Described in |
| | | Section 5.1.4.1.17.4 |
+------------+-----------------------------+----------------------+
| 0x41F0 | BlockAddIDValue | Described in |
| | | Section 5.1.4.1.17.1 |
+------------+-----------------------------+----------------------+
| 0x4254 | ContentCompAlgo | Described in |
| | | Section 5.1.4.1.31.6 |
+------------+-----------------------------+----------------------+
| 0x4255 | ContentCompSettings | Described in |
| | | Section 5.1.4.1.31.7 |
+------------+-----------------------------+----------------------+
| 0x437C | ChapLanguage | Described in |
| | | Section 5.1.7.1.4.11 |
+------------+-----------------------------+----------------------+
| 0x437D | ChapLanguageBCP47 | Described in |
| | | Section 5.1.7.1.4.12 |
+------------+-----------------------------+----------------------+
| 0x437E | ChapCountry | Described in |
| | | Section 5.1.7.1.4.13 |
+------------+-----------------------------+----------------------+
| 0x4444 | SegmentFamily | Described in |
| | | Section 5.1.2.7 |
+------------+-----------------------------+----------------------+
| 0x4461 | DateUTC | Described in |
| | | Section 5.1.2.11 |
+------------+-----------------------------+----------------------+
| 0x447A | TagLanguage | Described in |
| | | Section 5.1.8.1.2.2 |
+------------+-----------------------------+----------------------+
| 0x447B | TagLanguageBCP47 | Described in |
| | | Section 5.1.8.1.2.3 |
+------------+-----------------------------+----------------------+
| 0x4484 | TagDefault | Described in |
| | | Section 5.1.8.1.2.4 |
+------------+-----------------------------+----------------------+
| 0x4485 | TagBinary | Described in |
| | | Section 5.1.8.1.2.6 |
+------------+-----------------------------+----------------------+
| 0x4487 | TagString | Described in |
| | | Section 5.1.8.1.2.5 |
+------------+-----------------------------+----------------------+
| 0x4489 | Duration | Described in |
| | | Section 5.1.2.10 |
+------------+-----------------------------+----------------------+
| 0x44B4 | TagDefaultBogus | Reclaimed |
| | | (Appendix A.43) |
+------------+-----------------------------+----------------------+
| 0x450D | ChapProcessPrivate | Described in |
| | | Section 5.1.7.1.4.16 |
+------------+-----------------------------+----------------------+
| 0x45A3 | TagName | Described in |
| | | Section 5.1.8.1.2.1 |
+------------+-----------------------------+----------------------+
| 0x45B9 | EditionEntry | Described in |
| | | Section 5.1.7.1 |
+------------+-----------------------------+----------------------+
| 0x45BC | EditionUID | Described in |
| | | Section 5.1.7.1.1 |
+------------+-----------------------------+----------------------+
| 0x45DB | EditionFlagDefault | Described in |
| | | Section 5.1.7.1.2 |
+------------+-----------------------------+----------------------+
| 0x45DD | EditionFlagOrdered | Described in |
| | | Section 5.1.7.1.3 |
+------------+-----------------------------+----------------------+
| 0x465C | FileData | Described in |
| | | Section 5.1.6.1.4 |
+------------+-----------------------------+----------------------+
| 0x4660 | FileMediaType | Described in |
| | | Section 5.1.6.1.3 |
+------------+-----------------------------+----------------------+
| 0x4661 | FileUsedStartTime | Reclaimed |
| | | (Appendix A.41) |
+------------+-----------------------------+----------------------+
| 0x4662 | FileUsedEndTime | Reclaimed |
| | | (Appendix A.42) |
+------------+-----------------------------+----------------------+
| 0x466E | FileName | Described in |
| | | Section 5.1.6.1.2 |
+------------+-----------------------------+----------------------+
| 0x4675 | FileReferral | Reclaimed |
| | | (Appendix A.40) |
+------------+-----------------------------+----------------------+
| 0x467E | FileDescription | Described in |
| | | Section 5.1.6.1.1 |
+------------+-----------------------------+----------------------+
| 0x46AE | FileUID | Described in |
| | | Section 5.1.6.1.5 |
+------------+-----------------------------+----------------------+
| 0x47E1 | ContentEncAlgo | Described in |
| | | Section 5.1.4.1.31.9 |
+------------+-----------------------------+----------------------+
| 0x47E2 | ContentEncKeyID | Described in Section |
| | | 5.1.4.1.31.10 |
+------------+-----------------------------+----------------------+
| 0x47E3 | ContentSignature | Reclaimed |
| | | (Appendix A.33) |
+------------+-----------------------------+----------------------+
| 0x47E4 | ContentSigKeyID | Reclaimed |
| | | (Appendix A.34) |
+------------+-----------------------------+----------------------+
| 0x47E5 | ContentSigAlgo | Reclaimed |
| | | (Appendix A.35) |
+------------+-----------------------------+----------------------+
| 0x47E6 | ContentSigHashAlgo | Reclaimed |
| | | (Appendix A.36) |
+------------+-----------------------------+----------------------+
| 0x47E7 | ContentEncAESSettings | Described in Section |
| | | 5.1.4.1.31.11 |
+------------+-----------------------------+----------------------+
| 0x47E8 | AESSettingsCipherMode | Described in Section |
| | | 5.1.4.1.31.12 |
+------------+-----------------------------+----------------------+
| 0x4D80 | MuxingApp | Described in |
| | | Section 5.1.2.13 |
+------------+-----------------------------+----------------------+
| 0x4DBB | Seek | Described in |
| | | Section 5.1.1.1 |
+------------+-----------------------------+----------------------+
| 0x5031 | ContentEncodingOrder | Described in |
| | | Section 5.1.4.1.31.2 |
+------------+-----------------------------+----------------------+
| 0x5032 | ContentEncodingScope | Described in |
| | | Section 5.1.4.1.31.3 |
+------------+-----------------------------+----------------------+
| 0x5033 | ContentEncodingType | Described in |
| | | Section 5.1.4.1.31.4 |
+------------+-----------------------------+----------------------+
| 0x5034 | ContentCompression | Described in |
| | | Section 5.1.4.1.31.5 |
+------------+-----------------------------+----------------------+
| 0x5035 | ContentEncryption | Described in |
| | | Section 5.1.4.1.31.8 |
+------------+-----------------------------+----------------------+
| 0x535F | CueRefNumber | Reclaimed |
| | | (Appendix A.38) |
+------------+-----------------------------+----------------------+
| 0x536E | Name | Described in |
| | | Section 5.1.4.1.18 |
+------------+-----------------------------+----------------------+
| 0x5378 | CueBlockNumber | Described in |
| | | Section 5.1.5.1.2.5 |
+------------+-----------------------------+----------------------+
| 0x537F | TrackOffset | Reclaimed |
| | | (Appendix A.18) |
+------------+-----------------------------+----------------------+
| 0x53AB | SeekID | Described in |
| | | Section 5.1.1.1.1 |
+------------+-----------------------------+----------------------+
| 0x53AC | SeekPosition | Described in |
| | | Section 5.1.1.1.2 |
+------------+-----------------------------+----------------------+
| 0x53B8 | StereoMode | Described in |
| | | Section 5.1.4.1.28.3 |
+------------+-----------------------------+----------------------+
| 0x53B9 | OldStereoMode | Described in |
| | | Section 5.1.4.1.28.5 |
+------------+-----------------------------+----------------------+
| 0x53C0 | AlphaMode | Described in |
| | | Section 5.1.4.1.28.4 |
+------------+-----------------------------+----------------------+
| 0x54AA | PixelCropBottom | Described in |
| | | Section 5.1.4.1.28.8 |
+------------+-----------------------------+----------------------+
| 0x54B0 | DisplayWidth | Described in Section |
| | | 5.1.4.1.28.12 |
+------------+-----------------------------+----------------------+
| 0x54B2 | DisplayUnit | Described in Section |
| | | 5.1.4.1.28.14 |
+------------+-----------------------------+----------------------+
| 0x54B3 | AspectRatioType | Reclaimed |
| | | (Appendix A.24) |
+------------+-----------------------------+----------------------+
| 0x54BA | DisplayHeight | Described in Section |
| | | 5.1.4.1.28.13 |
+------------+-----------------------------+----------------------+
| 0x54BB | PixelCropTop | Described in |
| | | Section 5.1.4.1.28.9 |
+------------+-----------------------------+----------------------+
| 0x54CC | PixelCropLeft | Described in Section |
| | | 5.1.4.1.28.10 |
+------------+-----------------------------+----------------------+
| 0x54DD | PixelCropRight | Described in Section |
| | | 5.1.4.1.28.11 |
+------------+-----------------------------+----------------------+
| 0x55AA | FlagForced | Described in |
| | | Section 5.1.4.1.6 |
+------------+-----------------------------+----------------------+
| 0x55AB | FlagHearingImpaired | Described in |
| | | Section 5.1.4.1.7 |
+------------+-----------------------------+----------------------+
| 0x55AC | FlagVisualImpaired | Described in |
| | | Section 5.1.4.1.8 |
+------------+-----------------------------+----------------------+
| 0x55AD | FlagTextDescriptions | Described in |
| | | Section 5.1.4.1.9 |
+------------+-----------------------------+----------------------+
| 0x55AE | FlagOriginal | Described in |
| | | Section 5.1.4.1.10 |
+------------+-----------------------------+----------------------+
| 0x55AF | FlagCommentary | Described in |
| | | Section 5.1.4.1.11 |
+------------+-----------------------------+----------------------+
| 0x55B0 | Colour | Described in Section |
| | | 5.1.4.1.28.16 |
+------------+-----------------------------+----------------------+
| 0x55B1 | MatrixCoefficients | Described in Section |
| | | 5.1.4.1.28.17 |
+------------+-----------------------------+----------------------+
| 0x55B2 | BitsPerChannel | Described in Section |
| | | 5.1.4.1.28.18 |
+------------+-----------------------------+----------------------+
| 0x55B3 | ChromaSubsamplingHorz | Described in Section |
| | | 5.1.4.1.28.19 |
+------------+-----------------------------+----------------------+
| 0x55B4 | ChromaSubsamplingVert | Described in Section |
| | | 5.1.4.1.28.20 |
+------------+-----------------------------+----------------------+
| 0x55B5 | CbSubsamplingHorz | Described in Section |
| | | 5.1.4.1.28.21 |
+------------+-----------------------------+----------------------+
| 0x55B6 | CbSubsamplingVert | Described in Section |
| | | 5.1.4.1.28.22 |
+------------+-----------------------------+----------------------+
| 0x55B7 | ChromaSitingHorz | Described in Section |
| | | 5.1.4.1.28.23 |
+------------+-----------------------------+----------------------+
| 0x55B8 | ChromaSitingVert | Described in Section |
| | | 5.1.4.1.28.24 |
+------------+-----------------------------+----------------------+
| 0x55B9 | Range | Described in Section |
| | | 5.1.4.1.28.25 |
+------------+-----------------------------+----------------------+
| 0x55BA | TransferCharacteristics | Described in Section |
| | | 5.1.4.1.28.26 |
+------------+-----------------------------+----------------------+
| 0x55BB | Primaries | Described in Section |
| | | 5.1.4.1.28.27 |
+------------+-----------------------------+----------------------+
| 0x55BC | MaxCLL | Described in Section |
| | | 5.1.4.1.28.28 |
+------------+-----------------------------+----------------------+
| 0x55BD | MaxFALL | Described in Section |
| | | 5.1.4.1.28.29 |
+------------+-----------------------------+----------------------+
| 0x55D0 | MasteringMetadata | Described in Section |
| | | 5.1.4.1.28.30 |
+------------+-----------------------------+----------------------+
| 0x55D1 | PrimaryRChromaticityX | Described in Section |
| | | 5.1.4.1.28.31 |
+------------+-----------------------------+----------------------+
| 0x55D2 | PrimaryRChromaticityY | Described in Section |
| | | 5.1.4.1.28.32 |
+------------+-----------------------------+----------------------+
| 0x55D3 | PrimaryGChromaticityX | Described in Section |
| | | 5.1.4.1.28.33 |
+------------+-----------------------------+----------------------+
| 0x55D4 | PrimaryGChromaticityY | Described in Section |
| | | 5.1.4.1.28.34 |
+------------+-----------------------------+----------------------+
| 0x55D5 | PrimaryBChromaticityX | Described in Section |
| | | 5.1.4.1.28.35 |
+------------+-----------------------------+----------------------+
| 0x55D6 | PrimaryBChromaticityY | Described in Section |
| | | 5.1.4.1.28.36 |
+------------+-----------------------------+----------------------+
| 0x55D7 | WhitePointChromaticityX | Described in Section |
| | | 5.1.4.1.28.37 |
+------------+-----------------------------+----------------------+
| 0x55D8 | WhitePointChromaticityY | Described in Section |
| | | 5.1.4.1.28.38 |
+------------+-----------------------------+----------------------+
| 0x55D9 | LuminanceMax | Described in Section |
| | | 5.1.4.1.28.39 |
+------------+-----------------------------+----------------------+
| 0x55DA | LuminanceMin | Described in Section |
| | | 5.1.4.1.28.40 |
+------------+-----------------------------+----------------------+
| 0x55EE | MaxBlockAdditionID | Described in |
| | | Section 5.1.4.1.16 |
+------------+-----------------------------+----------------------+
| 0x5654 | ChapterStringUID | Described in |
| | | Section 5.1.7.1.4.2 |
+------------+-----------------------------+----------------------+
| 0x56AA | CodecDelay | Described in |
| | | Section 5.1.4.1.25 |
+------------+-----------------------------+----------------------+
| 0x56BB | SeekPreRoll | Described in |
| | | Section 5.1.4.1.26 |
+------------+-----------------------------+----------------------+
| 0x5741 | WritingApp | Described in |
| | | Section 5.1.2.14 |
+------------+-----------------------------+----------------------+
| 0x5854 | SilentTracks | Reclaimed |
| | | (Appendix A.1) |
+------------+-----------------------------+----------------------+
| 0x58D7 | SilentTrackNumber | Reclaimed |
| | | (Appendix A.2) |
+------------+-----------------------------+----------------------+
| 0x61A7 | AttachedFile | Described in |
| | | Section 5.1.6.1 |
+------------+-----------------------------+----------------------+
| 0x6240 | ContentEncoding | Described in |
| | | Section 5.1.4.1.31.1 |
+------------+-----------------------------+----------------------+
| 0x6264 | BitDepth | Described in |
| | | Section 5.1.4.1.29.4 |
+------------+-----------------------------+----------------------+
| 0x63A2 | CodecPrivate | Described in |
| | | Section 5.1.4.1.22 |
+------------+-----------------------------+----------------------+
| 0x63C0 | Targets | Described in |
| | | Section 5.1.8.1.1 |
+------------+-----------------------------+----------------------+
| 0x63C3 | ChapterPhysicalEquiv | Described in |
| | | Section 5.1.7.1.4.8 |
+------------+-----------------------------+----------------------+
| 0x63C4 | TagChapterUID | Described in |
| | | Section 5.1.8.1.1.5 |
+------------+-----------------------------+----------------------+
| 0x63C5 | TagTrackUID | Described in |
| | | Section 5.1.8.1.1.3 |
+------------+-----------------------------+----------------------+
| 0x63C6 | TagAttachmentUID | Described in |
| | | Section 5.1.8.1.1.6 |
+------------+-----------------------------+----------------------+
| 0x63C9 | TagEditionUID | Described in |
| | | Section 5.1.8.1.1.4 |
+------------+-----------------------------+----------------------+
| 0x63CA | TargetType | Described in |
| | | Section 5.1.8.1.1.2 |
+------------+-----------------------------+----------------------+
| 0x6624 | TrackTranslate | Described in |
| | | Section 5.1.4.1.27 |
+------------+-----------------------------+----------------------+
| 0x66A5 | TrackTranslateTrackID | Described in |
| | | Section 5.1.4.1.27.1 |
+------------+-----------------------------+----------------------+
| 0x66BF | TrackTranslateCodec | Described in |
| | | Section 5.1.4.1.27.2 |
+------------+-----------------------------+----------------------+
| 0x66FC | TrackTranslateEditionUID | Described in |
| | | Section 5.1.4.1.27.3 |
+------------+-----------------------------+----------------------+
| 0x67C8 | SimpleTag | Described in |
| | | Section 5.1.8.1.2 |
+------------+-----------------------------+----------------------+
| 0x68CA | TargetTypeValue | Described in |
| | | Section 5.1.8.1.1.1 |
+------------+-----------------------------+----------------------+
| 0x6911 | ChapProcessCommand | Described in |
| | | Section 5.1.7.1.4.17 |
+------------+-----------------------------+----------------------+
| 0x6922 | ChapProcessTime | Described in |
| | | Section 5.1.7.1.4.18 |
+------------+-----------------------------+----------------------+
| 0x6924 | ChapterTranslate | Described in |
| | | Section 5.1.2.8 |
+------------+-----------------------------+----------------------+
| 0x6933 | ChapProcessData | Described in |
| | | Section 5.1.7.1.4.19 |
+------------+-----------------------------+----------------------+
| 0x6944 | ChapProcess | Described in |
| | | Section 5.1.7.1.4.14 |
+------------+-----------------------------+----------------------+
| 0x6955 | ChapProcessCodecID | Described in |
| | | Section 5.1.7.1.4.15 |
+------------+-----------------------------+----------------------+
| 0x69A5 | ChapterTranslateID | Described in |
| | | Section 5.1.2.8.1 |
+------------+-----------------------------+----------------------+
| 0x69BF | ChapterTranslateCodec | Described in |
| | | Section 5.1.2.8.2 |
+------------+-----------------------------+----------------------+
| 0x69FC | ChapterTranslateEditionUID | Described in |
| | | Section 5.1.2.8.3 |
+------------+-----------------------------+----------------------+
| 0x6D80 | ContentEncodings | Described in |
| | | Section 5.1.4.1.31 |
+------------+-----------------------------+----------------------+
| 0x6DE7 | MinCache | Reclaimed |
| | | (Appendix A.16) |
+------------+-----------------------------+----------------------+
| 0x6DF8 | MaxCache | Reclaimed |
| | | (Appendix A.17) |
+------------+-----------------------------+----------------------+
| 0x6E67 | ChapterSegmentUUID | Described in |
| | | Section 5.1.7.1.4.6 |
+------------+-----------------------------+----------------------+
| 0x6EBC | ChapterSegmentEditionUID | Described in |
| | | Section 5.1.7.1.4.7 |
+------------+-----------------------------+----------------------+
| 0x6FAB | TrackOverlay | Reclaimed |
| | | (Appendix A.23) |
+------------+-----------------------------+----------------------+
| 0x7373 | Tag | Described in |
| | | Section 5.1.8.1 |
+------------+-----------------------------+----------------------+
| 0x7384 | SegmentFilename | Described in |
| | | Section 5.1.2.2 |
+------------+-----------------------------+----------------------+
| 0x73A4 | SegmentUUID | Described in |
| | | Section 5.1.2.1 |
+------------+-----------------------------+----------------------+
| 0x73C4 | ChapterUID | Described in |
| | | Section 5.1.7.1.4.1 |
+------------+-----------------------------+----------------------+
| 0x73C5 | TrackUID | Described in |
| | | Section 5.1.4.1.2 |
+------------+-----------------------------+----------------------+
| 0x7446 | AttachmentLink | Described in |
| | | Section 5.1.4.1.24 |
+------------+-----------------------------+----------------------+
| 0x75A1 | BlockAdditions | Described in |
| | | Section 5.1.3.5.2 |
+------------+-----------------------------+----------------------+
| 0x75A2 | DiscardPadding | Described in |
| | | Section 5.1.3.5.7 |
+------------+-----------------------------+----------------------+
| 0x7670 | Projection | Described in Section |
| | | 5.1.4.1.28.41 |
+------------+-----------------------------+----------------------+
| 0x7671 | ProjectionType | Described in Section |
| | | 5.1.4.1.28.42 |
+------------+-----------------------------+----------------------+
| 0x7672 | ProjectionPrivate | Described in Section |
| | | 5.1.4.1.28.43 |
+------------+-----------------------------+----------------------+
| 0x7673 | ProjectionPoseYaw | Described in Section |
| | | 5.1.4.1.28.44 |
+------------+-----------------------------+----------------------+
| 0x7674 | ProjectionPosePitch | Described in Section |
| | | 5.1.4.1.28.45 |
+------------+-----------------------------+----------------------+
| 0x7675 | ProjectionPoseRoll | Described in Section |
| | | 5.1.4.1.28.46 |
+------------+-----------------------------+----------------------+
| 0x78B5 | OutputSamplingFrequency | Described in |
| | | Section 5.1.4.1.29.2 |
+------------+-----------------------------+----------------------+
| 0x7BA9 | Title | Described in |
| | | Section 5.1.2.12 |
+------------+-----------------------------+----------------------+
| 0x7D7B | ChannelPositions | Reclaimed |
| | | (Appendix A.27) |
+------------+-----------------------------+----------------------+
| 0x22B59C | Language | Described in |
| | | Section 5.1.4.1.19 |
+------------+-----------------------------+----------------------+
| 0x22B59D | LanguageBCP47 | Described in |
| | | Section 5.1.4.1.20 |
+------------+-----------------------------+----------------------+
| 0x23314F | TrackTimestampScale | Described in |
| | | Section 5.1.4.1.15 |
+------------+-----------------------------+----------------------+
| 0x234E7A | DefaultDecodedFieldDuration | Described in |
| | | Section 5.1.4.1.14 |
+------------+-----------------------------+----------------------+
| 0x2383E3 | FrameRate | Reclaimed |
| | | (Appendix A.26) |
+------------+-----------------------------+----------------------+
| 0x23E383 | DefaultDuration | Described in |
| | | Section 5.1.4.1.13 |
+------------+-----------------------------+----------------------+
| 0x258688 | CodecName | Described in |
| | | Section 5.1.4.1.23 |
+------------+-----------------------------+----------------------+
| 0x26B240 | CodecDownloadURL | Reclaimed |
| | | (Appendix A.21) |
+------------+-----------------------------+----------------------+
| 0x2AD7B1 | TimestampScale | Described in |
| | | Section 5.1.2.9 |
+------------+-----------------------------+----------------------+
| 0x2EB524 | UncompressedFourCC | Described in Section |
| | | 5.1.4.1.28.15 |
+------------+-----------------------------+----------------------+
| 0x2FB523 | GammaValue | Reclaimed |
| | | (Appendix A.25) |
+------------+-----------------------------+----------------------+
| 0x3A9697 | CodecSettings | Reclaimed |
| | | (Appendix A.19) |
+------------+-----------------------------+----------------------+
| 0x3B4040 | CodecInfoURL | Reclaimed |
| | | (Appendix A.20) |
+------------+-----------------------------+----------------------+
| 0x3C83AB | PrevFilename | Described in |
| | | Section 5.1.2.4 |
+------------+-----------------------------+----------------------+
| 0x3CB923 | PrevUUID | Described in |
| | | Section 5.1.2.3 |
+------------+-----------------------------+----------------------+
| 0x3E83BB | NextFilename | Described in |
| | | Section 5.1.2.6 |
+------------+-----------------------------+----------------------+
| 0x3EB923 | NextUUID | Described in |
| | | Section 5.1.2.5 |
+------------+-----------------------------+----------------------+
| 0x1043A770 | Chapters | Described in |
| | | Section 5.1.7 |
+------------+-----------------------------+----------------------+
| 0x114D9B74 | SeekHead | Described in |
| | | Section 5.1.1 |
+------------+-----------------------------+----------------------+
| 0x1254C367 | Tags | Described in |
| | | Section 5.1.8 |
+------------+-----------------------------+----------------------+
| 0x1549A966 | Info | Described in |
| | | Section 5.1.2 |
+------------+-----------------------------+----------------------+
| 0x1654AE6B | Tracks | Described in |
| | | Section 5.1.4 |
+------------+-----------------------------+----------------------+
| 0x18538067 | Segment | Described in |
| | | Section 5.1 |
+------------+-----------------------------+----------------------+
| 0x1941A469 | Attachments | Described in |
| | | Section 5.1.6 |
+------------+-----------------------------+----------------------+
| 0x1C53BB6B | Cues | Described in |
| | | Section 5.1.5 |
+------------+-----------------------------+----------------------+
| 0x1F43B675 | Cluster | Described in |
| | | Section 5.1.3 |
+------------+-----------------------------+----------------------+
Table 54: IDs and Names for Matroska Element IDs Assigned by
RFC 9559
27.2. Chapter Codec IDs Registry
This document creates a new IANA registry called the "Matroska
Chapter Codec IDs" registry. The values correspond to the unsigned
integer ChapProcessCodecID value described in Section 5.1.7.1.4.15.
To register a new Chapter Codec ID in this registry, one needs a
Chapter Codec ID, a Change Controller (IETF or email of registrant),
and an optional reference to a document describing the Chapter Codec
ID.
The Chapter Codec IDs are to be allocated according to the "First
Come First Served" policy [RFC8126].
ChapProcessCodecID values of "0" and "1" are RESERVED to the IETF for
future use.
27.3. Media Types
Matroska files and streams are found in three main forms: audio-video
files, audio-only, and occasionally with stereoscopic video tracks.
Historically, Matroska files and streams have used the following
media types with an "x-" prefix. For better compatibility, a system
SHOULD be able to handle both formats. Newer systems SHOULD NOT use
the historic format and use the format that follows the [RFC6838]
format instead.
Please register three media types, the [RFC6838] templates are below:
27.3.1. For Files Containing Video Tracks
Type name: video
Subtype name: matroska
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: as per this document and RFC8794
Security considerations: See Section 26.
Interoperability considerations: Due to the extensibility of
Matroska, it is possible to encounter files with unknown but valid
EBML Elements. Readers should be ready to handle this case. The
fixed byte order, octet boundaries, and UTF-8 usage allow for
broad interoparability.
Published specification: THISRFC
Applications that use this media type: FFmpeg, VLC, ...
Fragment identifier considerations: N/A
Additional information:
Deprecated alias names for this type: video/x-matroska
Magic number(s): N/A
File extension(s): mkv
Macintosh file type code(s): N/A
Person & email address to contact for further information: IETF
CELLAR WG cellar@ietf.org
Intended usage: COMMON
Restrictions on usage: None
Author: IETF CELLAR WG
Change controller: IETF
27.3.2. For Files Containing Audio Tracks with No Video Tracks
Type name: audio
Subtype name: matroska
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: as per this document and RFC8794
Security considerations: See Section 26.
Interoperability considerations: Due to the extensibility of
Matroska, it is possible to encounter files with unknown but valid
EBML Elements. Readers should be ready to handle this case. The
fixed byte order, octet boundaries, and UTF-8 usage allow for
broad interoparability.
Published specification: THISRFC
Applications that use this media type: FFmpeg, VLC, ...
Fragment identifier considerations: N/A
Additional information:
Deprecated alias names for this type: audio/x-matroska
Magic number(s): N/A
File extension(s): mka
Macintosh file type code(s): N/A
Person & email address to contact for further information: IETF
CELLAR WG cellar@ietf.org
Intended usage: COMMON
Restrictions on usage: None
Author: IETF CELLAR WG
Change controller: IETF
27.3.3. For Files Containing a Stereoscopic Video Track
Type name: video
Subtype name: matroska-3d
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: as per this document and RFC8794
Security considerations: See Section 26.
Interoperability considerations: Due to the extensibility of
Matroska, it is possible to encounter files with unknown but valid
EBML Elements. Readers should be ready to handle this case. The
fixed byte order, octet boundaries, and UTF-8 usage allow for
broad interoparability.
Published specification: THISRFC
Applications that use this media type: FFmpeg, VLC, ...
Fragment identifier considerations: N/A
Additional information:
Deprecated alias names for this type: video/x-matroska-3d
Magic number(s): N/A
File extension(s): mk3d
Macintosh file type code(s): N/A
Person & email address to contact for further information: IETF
CELLAR WG cellar@ietf.org
Intended usage: COMMON
Restrictions on usage: None
Author: IETF CELLAR WG
Change controller: IETF
28. References
28.1. Normative References
[BCP47] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, .
[CIE-1931] Wikipedia, "CIE 1931 color space",
.
[ISO639-2] International Organization for Standardization, "Codes for
the Representation of Names of Languages", ISO 639-2,
December 2017, .
[ISO9899] International Organization for Standardization,
"Information technology -- Programming languages -- C",
ISO/IEC 9899:2018, June 2018,
.
[ITU-H.273]
ITU-T, "Coding-independent code points for video signal
type identification", ITU-T Recommendation H.273,
September 2023,
.
[RFC1950] Deutsch, P. and J. Gailly, "ZLIB Compressed Data Format
Specification version 3.3", RFC 1950,
DOI 10.17487/RFC1950, May 1996,
.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122,
DOI 10.17487/RFC4122, July 2005,
.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
.
[RFC8081] Lilley, C., "The "font" Top-Level Media Type", RFC 8081,
DOI 10.17487/RFC8081, February 2017,
.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, .
[RFC8794] Lhomme, S., Rice, D., and M. Bunkus, "Extensible Binary
Meta Language", RFC 8794, DOI 10.17487/RFC8794, July 2020,
.
28.2. Informative References
[AVIFormat]
Microsoft Corporation, "AVI RIFF File Reference", June
2023, .
[Blowfish] Schneier, B., "The Blowfish Encryption Algorithm", 1993,
.
[BZIP2] Seward, J., "bzip2", July 2019,
.
[DivXTrickTrack]
"Smooth FF/RW", December 2010,
.
[DivXWorldFonts]
"World Fonts", December 2010,
.
[DVD-Video]
DVD Forum, "DVD-Books: Part 3 DVD-Video Book", November
1995, .
[Err7189] RFC Errata, Erratum ID 7189, RFC 8794,
.
[Err7191] RFC Errata, Erratum ID 7191, RFC 8794,
.
[FIPS197] National Institute of Standards and Technology (NIST),
"Advanced Encryption Standard (AES)", FIPS PUB 197,
DOI 10.6028/NIST.FIPS.197, November 2001,
.
[FIPS46-3] National Institute of Standards and Technology (NIST),
"Data Encryption Standard (DES)", FIPS PUB 46, October
1999,
.
[FourCC-RGB]
FOURCC, "RGB pixel formats",
.
[FourCC-YUV]
FOURCC, "YUV pixel formats",
.
[JPEG] ITU, "INFORMATION TECHNOLOGY - DIGITAL COMPRESSION AND
CODING OF CONTINUOUS-TONE STILL IMAGES - REQUIREMENTS AND
GUIDELINES", ITU Recommendation T.81, September 1992,
.
[LZO] Tarreau, W. and R. Rodgman, "LZO stream format as
understood by Linux's LZO decompressor", October 2018,
.
[MatroskaCodec]
Lhomme, S., Bunkus, M., and D. Rice, "Matroska Media
Container Codec Specifications", Work in Progress,
Internet-Draft, draft-ietf-cellar-codec-12, 27 January
2024, .
[MatroskaTags]
Lhomme, S., Bunkus, M., and D. Rice, "Matroska Media
Container Tag Specifications", Work in Progress, Internet-
Draft, draft-ietf-cellar-tags-12, 22 October 2023,
.
[MCF] "MCF specification, introduction",
.
[MSRGB] Microsoft Corporation, "Compression Enumeration", June
2021, .
[MSYUV16] Microsoft Corporation, "10-bit and 16-bit YUV Video
Formats", November 2022, .
[MSYUV8] Microsoft Corporation, "Recommended 8-Bit YUV Formats for
Video Rendering", January 2021,
.
[RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol",
STD 9, RFC 959, DOI 10.17487/RFC0959, October 1985,
.
[RFC2083] Boutell, T., "PNG (Portable Network Graphics)
Specification Version 1.0", RFC 2083,
DOI 10.17487/RFC2083, March 1997,
.
[RFC3533] Pfeiffer, S., "The Ogg Encapsulation Format Version 0",
RFC 3533, DOI 10.17487/RFC3533, May 2003,
.
[RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet
Denial-of-Service Considerations", RFC 4732,
DOI 10.17487/RFC4732, December 2006,
.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
.
[SMB-CIFS] Microsoft Corporation, "[MS-CIFS]: Common Internet File
System (CIFS) Protocol", October 2020,
.
[SP800-38A]
National Institute of Standards and Technology (NIST),
"Recommendation for Block Cipher Modes of Operation:
Methods and Techniques", DOI 10.6028/NIST.SP.800-38A, NIST
Special Publication 800-38A, December 2001,
.
[SP800-67] National Institute of Standards and Technology (NIST),
"Recommendation for the Triple Data Encryption Algorithm
(TDEA) Block Cipher", DOI 10.6028/NIST.SP.800-67r2, NIST
Special Publication 800-67, November 2017,
.
[Twofish] Schneier, B., Kelsey, J., Whiting, D., Wagner, D., Hall,
C., and N. Ferguson, "Twofish: A 128-Bit Block Cipher",
June 1998, .
[WebM-Enc] Galligan, F., "WebM Encryption", September 2016,
.
[WebVTT] Pieters, S., Pfeiffer, S., Ed., Jaegenstedt, P., and I.
Hickson, "WebVTT: The Web Video Text Tracks Format", W3C
Candidate Recommendation, April 2019,
.
Appendix A. Historic Deprecated Elements
Since Matroska has evolved since 2002, many parts that were
considered for use in the format were never used and often
incorrectly designed. Many of the elements that were defined then
are not found in any known files, but were part of public specs.
DivX also had a few custom elements that were designed for custom
features.
We list these elements that have a known ID that SHOULD NOT be reused
to avoid colliding with existing files. They might be reassigned by
IANA in the future if there are no more IDs for a given size. A
short description of what each ID was used for is included, but the
text is not normative.
A.1. SilentTracks Element
type / id: master / 0x5854
path: \Segment\Cluster\SilentTracks
documentation: The list of tracks that are not used in that part of
the stream. It is useful when using overlay tracks on seeking or
deciding what track to use.
A.2. SilentTrackNumber Element
type / id: uinteger / 0x58D7
path: \Segment\Cluster\SilentTracks\SilentTrackNumber
documentation: One of the track numbers that are not used from now
on in the stream. It could change later if it is not specified as
silent in a further Cluster.
A.3. BlockVirtual Element
type / id: binary / 0xA2
path: \Segment\Cluster\BlockGroup\BlockVirtual
documentation: A Block with no data. It must be stored in the
stream at the place that the real Block would be in display order.
A.4. ReferenceVirtual Element
type / id: integer / 0xFD
path: \Segment\Cluster\BlockGroup\ReferenceVirtual
documentation: The Segment Position of the data that would otherwise
be in position of the virtual block.
A.5. Slices Element
type / id: master / 0x8E
path: \Segment\Cluster\BlockGroup\Slices
documentation: Contains slices description.
A.6. TimeSlice Element
type / id: master / 0xE8
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice
documentation: Contains extra time information about the data
contained in the Block. Being able to interpret this Element is
not required for playback.
A.7. LaceNumber Element
type / id: uinteger / 0xCC
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\LaceNumber
documentation: The reverse number of the frame in the lace (0 is the
last frame, 1 is the next to last, etc.). Being able to interpret
this Element is not required for playback.
A.8. FrameNumber Element
type / id: uinteger / 0xCD
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\FrameNumber
documentation: The number of the frame to generate from this lace
with this delay (allows for the generation of many frames from the
same Block/Frame).
A.9. BlockAdditionID Element
type / id: uinteger / 0xCB
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\BlockAdditionID
documentation: The ID of the BlockAdditional Element (0 is the main
Block).
A.10. Delay Element
type / id: uinteger / 0xCE
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\Delay
documentation: The delay to apply to the Element expressed in Track
Ticks; see Section 11.1.
A.11. SliceDuration Element
type / id: uinteger / 0xCF
path: \Segment\Cluster\BlockGroup\Slices\TimeSlice\SliceDuration
documentation: The duration to apply to the Element expressed in
Track Ticks; see Section 11.1.
A.12. ReferenceFrame Element
type / id: master / 0xC8
path: \Segment\Cluster\BlockGroup\ReferenceFrame
documentation: Contains information about the last reference frame.
See [DivXTrickTrack].
A.13. ReferenceOffset Element
type / id: uinteger / 0xC9
path: \Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceOffset
documentation: The relative offset, in bytes, from the previous
BlockGroup element for this Smooth FF/RW video track to the
containing BlockGroup element. See [DivXTrickTrack].
A.14. ReferenceTimestamp Element
type / id: uinteger / 0xCA
path: \Segment\Cluster\BlockGroup\ReferenceFrame\ReferenceTimestamp
documentation: The timestamp of the BlockGroup pointed to by
ReferenceOffset expressed in Track Ticks; see Section 11.1. See
[DivXTrickTrack].
A.15. EncryptedBlock Element
type / id: binary / 0xAF
path: \Segment\Cluster\EncryptedBlock
documentation: Similar to SimpleBlock (see Section 10.2), but the
data inside the Block is Transformed (encrypt and/or signed).
A.16. MinCache Element
type / id: uinteger / 0x6DE7
path: \Segment\Tracks\TrackEntry\MinCache
documentation: The minimum number of frames a player should be able
to cache during playback. If set to 0, the reference pseudo-cache
system is not used.
A.17. MaxCache Element
type / id: uinteger / 0x6DF8
path: \Segment\Tracks\TrackEntry\MaxCache
documentation: The maximum cache size necessary to store referenced
frames in and the current frame. 0 means no cache is needed.
A.18. TrackOffset Element
type / id: integer / 0x537F
path: \Segment\Tracks\TrackEntry\TrackOffset
documentation: A value to add to the Block's Timestamp expressed in
Matroska Ticks -- i.e., in nanoseconds; see Section 11.1. This
can be used to adjust the playback offset of a track.
A.19. CodecSettings Element
type / id: utf-8 / 0x3A9697
path: \Segment\Tracks\TrackEntry\CodecSettings
documentation: A string describing the encoding setting used.
A.20. CodecInfoURL Element
type / id: string / 0x3B4040
path: \Segment\Tracks\TrackEntry\CodecInfoURL
documentation: A URL to find information about the codec used.
A.21. CodecDownloadURL Element
type / id: string / 0x26B240
path: \Segment\Tracks\TrackEntry\CodecDownloadURL
documentation: A URL to download about the codec used.
A.22. CodecDecodeAll Element
type / id: uinteger / 0xAA
path: \Segment\Tracks\TrackEntry\CodecDecodeAll
documentation: Set to 1 if the codec can decode potentially damaged
data.
A.23. TrackOverlay Element
type / id: uinteger / 0x6FAB
path: \Segment\Tracks\TrackEntry\TrackOverlay
documentation: Specify that this track is an overlay track for the
Track specified (in the u-integer). That means when this track
has a gap on SilentTracks, the overlay track should be used
instead. The order of multiple TrackOverlay matters; the first
one is the one that should be used. If the first one is not
found, it should be the second, etc.
A.24. AspectRatioType Element
type / id: uinteger / 0x54B3
path: \Segment\Tracks\TrackEntry\Video\AspectRatioType
documentation: Specify the possible modifications to the aspect
ratio.
A.25. GammaValue Element
type / id: float / 0x2FB523
path: \Segment\Tracks\TrackEntry\Video\GammaValue
documentation: Gamma Value.
A.26. FrameRate Element
type / id: float / 0x2383E3
path: \Segment\Tracks\TrackEntry\Video\FrameRate
documentation: Number of frames per second. This value is
Informational only. It is intended for constant frame rate
streams and should not be used for a variable frame rate
TrackEntry.
A.27. ChannelPositions Element
type / id: binary / 0x7D7B
path: \Segment\Tracks\TrackEntry\Audio\ChannelPositions
documentation: Table of horizontal angles for each successive
channel.
A.28. TrickTrackUID Element
type / id: uinteger / 0xC0
path: \Segment\Tracks\TrackEntry\TrickTrackUID
documentation: The TrackUID of the Smooth FF/RW video in the paired
EBML structure corresponding to this video track. See
[DivXTrickTrack].
A.29. TrickTrackSegmentUID Element
type / id: binary / 0xC1
path: \Segment\Tracks\TrackEntry\TrickTrackSegmentUID
documentation: The SegmentUID of the Segment containing the track
identified by TrickTrackUID. See [DivXTrickTrack].
A.30. TrickTrackFlag Element
type / id: uinteger / 0xC6
path: \Segment\Tracks\TrackEntry\TrickTrackFlag
documentation: Set to 1 if this video track is a Smooth FF/RW track.
If set to 1, MasterTrackUID and MasterTrackSegUID should be
present and BlockGroups for this track must contain ReferenceFrame
structures. Otherwise, TrickTrackUID and TrickTrackSegUID must be
present if this track has a corresponding Smooth FF/RW track. See
[DivXTrickTrack].
A.31. TrickMasterTrackUID Element
type / id: uinteger / 0xC7
path: \Segment\Tracks\TrackEntry\TrickMasterTrackUID
documentation: The TrackUID of the video track in the paired EBML
structure that corresponds to this Smooth FF/RW track. See
[DivXTrickTrack].
A.32. TrickMasterTrackSegmentUID Element
type / id: binary / 0xC4
path: \Segment\Tracks\TrackEntry\TrickMasterTrackSegmentUID
documentation: The SegmentUID of the Segment containing the track
identified by MasterTrackUID. See [DivXTrickTrack].
A.33. ContentSignature Element
type / id: binary / 0x47E3
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentSignature
documentation: A cryptographic signature of the contents.
A.34. ContentSigKeyID Element
type / id: binary / 0x47E4
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentSigKeyID
documentation: This is the ID of the private key that the data was
signed with.
A.35. ContentSigAlgo Element
type / id: uinteger / 0x47E5
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentSigAlgo
documentation: The algorithm used for the signature.
A.36. ContentSigHashAlgo Element
type / id: uinteger / 0x47E6
path: \Segment\Tracks\TrackEntry\ContentEncodings\ContentEncoding\Co
ntentEncryption\ContentSigHashAlgo
documentation: The hash algorithm used for the signature.
A.37. CueRefCluster Element
type / id: uinteger / 0x97
path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefCl
uster
documentation: The Segment Position of the Cluster containing the
referenced Block.
A.38. CueRefNumber Element
type / id: uinteger / 0x535F
path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefNu
mber
documentation: Number of the referenced Block of Track X in the
specified Cluster.
A.39. CueRefCodecState Element
type / id: uinteger / 0xEB
path: \Segment\Cues\CuePoint\CueTrackPositions\CueReference\CueRefCo
decState
documentation: The Segment Position of the Codec State corresponding
to this referenced Element. 0 means that the data is taken from
the initial Track Entry.
A.40. FileReferral Element
type / id: binary / 0x4675
path: \Segment\Attachments\AttachedFile\FileReferral
documentation: A binary value that a track/codec can refer to when
the attachment is needed.
A.41. FileUsedStartTime Element
type / id: uinteger / 0x4661
path: \Segment\Attachments\AttachedFile\FileUsedStartTime
documentation: The timestamp at which this optimized font attachment
comes into context and is expressed in Segment Ticks, which are
based on TimestampScale. See [DivXWorldFonts].
A.42. FileUsedEndTime Element
type / id: uinteger / 0x4662
path: \Segment\Attachments\AttachedFile\FileUsedEndTime
documentation: The timestamp at which this optimized font attachment
goes out of context and is expressed in Segment Ticks, which are
based on TimestampScale. See [DivXWorldFonts].
A.43. TagDefaultBogus Element
type / id: uinteger / 0x44B4
path: \Segment\Tags\Tag\+SimpleTag\TagDefaultBogus
documentation: A variant of the TagDefault element with a bogus
Element ID. See Section 5.1.8.1.2.4.
Authors' Addresses
Steve Lhomme
Email: slhomme@matroska.org
Moritz Bunkus
Email: moritz@bunkus.org
Dave Rice
Email: dave@dericed.com