http://www.rfc-editor.org/rfc/rfc6843.txt
RFC 6843: RTP Control Protocol (RTCP) Extended Report (XR) Block for Delay Metric Reporting, A. Clark, K. Gross, Q. Wu2013-01-01T23:00:00-00:00This document defines an RTP Control Protocol (RTCP) Extended Report (XR) block that allows the reporting of delay metrics for use in a range of Real-time Transport Protocol (RTP) applications. [STANDARDS-TRACK]