Using Simulcast in SDP and RTP Sessions
draft-ietf-mmusic-sdp-simulcast-08
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draft-burman-mmusic-sdp-simulcast
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Network Working Group B. Burman
Internet-Draft M. Westerlund
Intended status: Standards Track Ericsson
Expires: September 14, 2017 S. Nandakumar
M. Zanaty
Cisco
March 13, 2017
Using Simulcast in SDP and RTP Sessions
draft-ietf-mmusic-sdp-simulcast-08
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.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 14, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
Burman, et al. Expires September 14, 2017 [Page 1]
Internet-Draft Simulcast March 2017
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6. Detailed Description . . . . . . . . . . . . . . . . . . . . 10
6.1. Simulcast Attribute . . . . . . . . . . . . . . . . . . . 10
6.2. Simulcast Capability . . . . . . . . . . . . . . . . . . 11
6.3. Offer/Answer Use . . . . . . . . . . . . . . . . . . . . 14
6.3.1. Generating the Initial SDP Offer . . . . . . . . . . 14
6.3.2. Creating the SDP Answer . . . . . . . . . . . . . . . 14
6.3.3. Offerer Processing the SDP Answer . . . . . . . . . . 15
6.3.4. Modifying the Session . . . . . . . . . . . . . . . . 16
6.4. Use with Declarative SDP . . . . . . . . . . . . . . . . 16
6.5. Relating Simulcast Streams . . . . . . . . . . . . . . . 16
6.6. Signaling Examples . . . . . . . . . . . . . . . . . . . 17
6.6.1. Single-Source Client . . . . . . . . . . . . . . . . 17
6.6.2. Multi-Source Client . . . . . . . . . . . . . . . . . 18
7. RTP Aspects . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.1. Outgoing from Endpoint with Media Source . . . . . . . . 21
7.2. RTP Middlebox to Receiver . . . . . . . . . . . . . . . . 21
7.2.1. Media-Switching Mixer . . . . . . . . . . . . . . . . 23
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