Using Simulcast in SDP and RTP Sessions
draft-ietf-mmusic-sdp-simulcast-10

Document Type Active Internet-Draft (mmusic WG)
Last updated 2017-11-02 (latest revision 2017-07-20)
Replaces draft-burman-mmusic-sdp-simulcast
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Stream WG state WG Consensus: Waiting for Write-Up (wg milestone: Oct 2017 - Submit Using Simulca... )
Revised I-D Needed - Issue raised by WGLC
Document shepherd Flemming Andreasen
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Network Working Group                                          B. Burman
Internet-Draft                                             M. Westerlund
Intended status: Standards Track                                Ericsson
Expires: January 21, 2018                                  S. Nandakumar
                                                               M. Zanaty
                                                                   Cisco
                                                           July 20, 2017

                Using Simulcast in SDP and RTP Sessions
                   draft-ietf-mmusic-sdp-simulcast-10

Abstract

   In some application scenarios it may be desirable to send multiple
   differently encoded versions of the same media source in different
   RTP streams.  This is called simulcast.  This document describes how
   to accomplish simulcast in RTP and how to signal it in SDP.  The
   described solution uses an RTP/RTCP identification method to identify
   RTP streams belonging to the same media source, and makes an
   extension to SDP to relate those RTP streams as being different
   simulcast formats of that media source.  The SDP extension consists
   of a new media level SDP attribute that expresses capability to send
   and/or receive simulcast RTP streams.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on January 21, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Burman, et al.          Expires January 21, 2018                [Page 1]
Internet-Draft                  Simulcast                      July 2017

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   5
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Reaching a Diverse Set of Receivers . . . . . . . . . . .   6
     3.2.  Application Specific Media Source Handling  . . . . . . .   7
     3.3.  Receiver Media Source Preferences . . . . . . . . . . . .   7
   4.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Detailed Description  . . . . . . . . . . . . . . . . . . . .  10
     5.1.  Simulcast Attribute . . . . . . . . . . . . . . . . . . .  10
     5.2.  Simulcast Capability  . . . . . . . . . . . . . . . . . .  11
     5.3.  Offer/Answer Use  . . . . . . . . . . . . . . . . . . . .  13
       5.3.1.  Generating the Initial SDP Offer  . . . . . . . . . .  13
       5.3.2.  Creating the SDP Answer . . . . . . . . . . . . . . .  13
       5.3.3.  Offerer Processing the SDP Answer . . . . . . . . . .  14
       5.3.4.  Modifying the Session . . . . . . . . . . . . . . . .  15
     5.4.  Use with Declarative SDP  . . . . . . . . . . . . . . . .  15
     5.5.  Relating Simulcast Streams  . . . . . . . . . . . . . . .  16
     5.6.  Signaling Examples  . . . . . . . . . . . . . . . . . . .  16
       5.6.1.  Single-Source Client  . . . . . . . . . . . . . . . .  17
       5.6.2.  Multi-Source Client . . . . . . . . . . . . . . . . .  18
   6.  RTP Aspects . . . . . . . . . . . . . . . . . . . . . . . . .  21
     6.1.  Outgoing from Endpoint with Media Source  . . . . . . . .  21
     6.2.  RTP Middlebox to Receiver . . . . . . . . . . . . . . . .  21
       6.2.1.  Media-Switching Mixer . . . . . . . . . . . . . . . .  22
       6.2.2.  Selective Forwarding Middlebox  . . . . . . . . . . .  24
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