http://www.rfc-editor.org/rfc/rfc7266.txt
RFC 7266: RTP Control Protocol (RTCP) Extended Report (XR) Blocks for Mean Opinion Score (MOS) Metric Reporting, A. Clark, Q. Wu, R. Schott, G. Zorn2014-06-01T23:00:00-00:00This document defines an RTP Control Protocol (RTCP) Extended Report (XR) Block including two new segment types and associated Session Description Protocol (SDP) parameters that allow the reporting of mean opinion score (MOS) Metrics for use in a range of RTP applications.