RTP Stream Identifier Source Description (SDES)
draft-ietf-avtext-rid-09
Network Working Group A. Roach
Internet-Draft Mozilla
Intended status: Standards Track S. Nandakumar
Expires: April 9, 2017 Cisco Systems
P. Thatcher
Google
October 06, 2016
RTP Stream Identifier Source Description (SDES)
draft-ietf-avtext-rid-09
Abstract
This document defines and registers two new RTCP Stream Identifier
Source Description (SDES) items. One, named RtpStreamId, is used for
unique identification of RTP streams. The other,
RepairedRtpStreamId, can be used to identify which stream a
redundancy RTP stream is to be used to repair.
Status of This Memo
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This Internet-Draft will expire on April 9, 2017.
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Roach, et al. Expires April 9, 2017 [Page 1]
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Usage of RtpStreamId and RepairedRtpStreamId in RTP and RTCP 3
3.1. RTCP 'RtpStreamId' SDES Extension . . . . . . . . . . . . 5
3.2. RTCP 'RepairedRtpStreamId' SDES Extension . . . . . . . . 5
3.3. RTP 'RtpStreamId' and 'RepairedRtpStreamId' Header
Extensions . . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4.1. New RtpStreamId SDES item . . . . . . . . . . . . . . . . 6
4.2. New RepairRtpStreamId SDES item . . . . . . . . . . . . . 6
4.3. New RtpStreamId Header Extension URI . . . . . . . . . . 7
4.4. New RepairRtpStreamId Header Extension URI . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
RTP sessions frequently consist of multiple streams, each of which is
identified at any given time by its SSRC; however, the SSRC
associated with a stream is not guaranteed to be stable over its
lifetime. Within a session, these streams can be tagged with a
number of identifiers, including CNAMEs and MSIDs
[I-D.ietf-mmusic-msid]. Unfortunately, none of these have the proper
ordinality to refer to an individual stream; all such identifiers can
appear in more than one stream at a time. While approaches that use
unique Payload Types (PTs) per stream have been used in some
applications, this is a semantic overloading of that field, and one
for which its size is inadequate: in moderately complex systems that
use PT to uniquely identify every potential combination of codec
configuration and unique stream, it is possible to simply run out of
values.
To address this situation, we define a new RTCP Stream Identifier
Source Description (SDES) identifier, RtpStreamId, that uniquely
identifies a single RTP stream. A key motivator for defining this
identifier is the ability to differentiate among different encodings
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