draft-ietf-avt-rapid-rtp-sync-09.txt | draft-ietf-avt-rapid-rtp-sync-10.txt | |||
---|---|---|---|---|
Network Working Group C. Perkins | Network Working Group C. Perkins | |||
Internet-Draft University of Glasgow | Internet-Draft University of Glasgow | |||
Updates: RFC3550 T. Schierl | Updates: 3550 (if approved) T. Schierl | |||
(if approved) Fraunhofer HHI | Intended status: Standards Track Fraunhofer HHI | |||
Intended status: Standards Track January 8, 2010 | Expires: November 6, 2010 May 5, 2010 | |||
Expires: July 12, 2010 | ||||
Rapid Synchronisation of RTP Flows | Rapid Synchronisation of RTP Flows | |||
draft-ietf-avt-rapid-rtp-sync-09.txt | draft-ietf-avt-rapid-rtp-sync-10.txt | |||
Status of this Memo | ||||
This Internet-Draft is submitted to IETF in full conformance with the | ||||
provisions of BCP 78 and BCP 79. | ||||
Internet-Drafts are working documents of the Internet Engineering | ||||
Task Force (IETF), its areas, and its working groups. Note that | ||||
other groups may also distribute working documents as Internet- | ||||
Drafts. | ||||
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." | ||||
The list of current Internet-Drafts can be accessed at | ||||
http://www.ietf.org/ietf/1id-abstracts.txt. | ||||
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This Internet-Draft will expire on July 12, 2010. | ||||
Copyright Notice | ||||
Copyright (c) 2010 IETF Trust and the persons identified as the | ||||
document authors. All rights reserved. | ||||
This document is subject to BCP 78 and the IETF Trust's Legal | ||||
Provisions Relating to IETF Documents in effect on the date of | ||||
publication of this document (http://trustee.ietf.org/license-info). | ||||
Please review these documents carefully, as they describe your rights | ||||
and restrictions with respect to this document. | ||||
Abstract | Abstract | |||
This memo outlines how RTP sessions are synchronised, and discusses | This memo outlines how RTP sessions are synchronised, and discusses | |||
how rapidly such synchronisation can occur. We show that most RTP | how rapidly such synchronisation can occur. We show that most RTP | |||
sessions can be synchronised immediately, but that the use of video | sessions can be synchronised immediately, but that the use of video | |||
switching multipoint conference units (MCUs) or large source specific | switching multipoint conference units (MCUs) or large source specific | |||
multicast (SSM) groups can greatly increase the synchronisation | multicast (SSM) groups can greatly increase the synchronisation | |||
delay. This increase in delay can be unacceptable to some | delay. This increase in delay can be unacceptable to some | |||
applications that use layered and/or multi-description codecs. | applications that use layered and/or multi-description codecs. | |||
skipping to change at page 3, line 5 ¶ | skipping to change at page 1, line 32 ¶ | |||
This memo introduces three mechanisms to reduce the synchronisation | This memo introduces three mechanisms to reduce the synchronisation | |||
delay for such sessions. First, it updates the RTP Control Protocol | delay for such sessions. First, it updates the RTP Control Protocol | |||
(RTCP) timing rules to reduce the initial synchronisation delay for | (RTCP) timing rules to reduce the initial synchronisation delay for | |||
SSM sessions. Second, a new feedback packet is defined for use with | SSM sessions. Second, a new feedback packet is defined for use with | |||
the Extended RTP Profile for RTCP-based Feedback (RTP/AVPF), allowing | the Extended RTP Profile for RTCP-based Feedback (RTP/AVPF), allowing | |||
video switching MCUs to rapidly request resynchronisation. Finally, | video switching MCUs to rapidly request resynchronisation. Finally, | |||
new RTP header extensions are defined to allow rapid synchronisation | new RTP header extensions are defined to allow rapid synchronisation | |||
of late joiners, and guarantee correct timestamp based decoding order | of late joiners, and guarantee correct timestamp based decoding order | |||
recovery for layered codecs in the presence of clock skew. | recovery for layered codecs in the presence of clock skew. | |||
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 November 6, 2010. | ||||
Copyright Notice | ||||
Copyright (c) 2010 IETF Trust and the persons identified as the | ||||
document authors. All rights reserved. | ||||
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 | Table of Contents | |||
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 | 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 | |||
2. Synchronisation of RTP Flows . . . . . . . . . . . . . . . . . 5 | 2. Synchronisation of RTP Flows . . . . . . . . . . . . . . . . . 4 | |||
2.1. Initial Synchronisation Delay . . . . . . . . . . . . . . 6 | 2.1. Initial Synchronisation Delay . . . . . . . . . . . . . . 5 | |||
2.1.1. Unicast Sessions . . . . . . . . . . . . . . . . . . . 6 | 2.1.1. Unicast Sessions . . . . . . . . . . . . . . . . . . . 5 | |||
2.1.2. Source Specific Multicast (SSM) Sessions . . . . . . . 7 | 2.1.2. Source Specific Multicast (SSM) Sessions . . . . . . . 6 | |||
2.1.3. Any Source Multicast (ASM) Sessions . . . . . . . . . 8 | 2.1.3. Any Source Multicast (ASM) Sessions . . . . . . . . . 7 | |||
2.1.4. Discussion . . . . . . . . . . . . . . . . . . . . . . 9 | 2.1.4. Discussion . . . . . . . . . . . . . . . . . . . . . . 8 | |||
2.2. Synchronisation for Late Joiners . . . . . . . . . . . . . 9 | 2.2. Synchronisation for Late Joiners . . . . . . . . . . . . . 8 | |||
3. Reducing RTP Synchronisation Delays . . . . . . . . . . . . . 10 | 3. Reducing RTP Synchronisation Delays . . . . . . . . . . . . . 9 | |||
3.1. Reduced Initial RTCP Interval for SSM Senders . . . . . . 10 | 3.1. Reduced Initial RTCP Interval for SSM Senders . . . . . . 9 | |||
3.2. Rapid Resynchronisation Request . . . . . . . . . . . . . 11 | 3.2. Rapid Resynchronisation Request . . . . . . . . . . . . . 10 | |||
3.3. In-band Delivery of Synchronisation Metadata . . . . . . . 12 | 3.3. In-band Delivery of Synchronisation Metadata . . . . . . . 11 | |||
4. Application to Decoding Order Recovery in Layered Codecs . . . 14 | 4. Application to Decoding Order Recovery in Layered Codecs . . . 13 | |||
4.1. In-band Synchronisation for Decoding Order Recovery . . . 15 | 4.1. In-band Synchronisation for Decoding Order Recovery . . . 14 | |||
4.2. Timestamp based decoding order recovery . . . . . . . . . 16 | 4.2. Timestamp based decoding order recovery . . . . . . . . . 15 | |||
4.3. Example . . . . . . . . . . . . . . . . . . . . . . . . . 17 | 4.3. Example . . . . . . . . . . . . . . . . . . . . . . . . . 16 | |||
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18 | 5. Security Considerations . . . . . . . . . . . . . . . . . . . 17 | |||
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 | 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 | |||
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19 | 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 | |||
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 | 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 | |||
8.1. Normative References . . . . . . . . . . . . . . . . . . . 19 | 8.1. Normative References . . . . . . . . . . . . . . . . . . . 18 | |||
8.2. Informative References . . . . . . . . . . . . . . . . . . 20 | 8.2. Informative References . . . . . . . . . . . . . . . . . . 19 | |||
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21 | Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20 | |||
1. Introduction | 1. Introduction | |||
When using RTP to deliver multimedia content it's often necessary to | When using RTP to deliver multimedia content it's often necessary to | |||
synchronise playout of audio and video components of a presentation. | synchronise playout of audio and video components of a presentation. | |||
This is achieved using information contained in RTP Control Protocol | This is achieved using information contained in RTP Control Protocol | |||
(RTCP) Sender Report (SR) packets [1]. These are sent periodically, | (RTCP) Sender Report (SR) packets [1]. These are sent periodically, | |||
and the components of a multimedia session cannot be synchronised | and the components of a multimedia session cannot be synchronised | |||
until sufficient RTCP SR packets have been received for each RTP flow | until sufficient RTCP SR packets have been received for each RTP flow | |||
to allow the receiver to establish mappings between the media clock | to allow the receiver to establish mappings between the media clock | |||
skipping to change at page 20, line 8 ¶ | skipping to change at page 19, line 8 ¶ | |||
"RTP: A Transport Protocol for Real-Time Applications", STD 64, | "RTP: A Transport Protocol for Real-Time Applications", STD 64, | |||
RFC 3550, July 2003. | RFC 3550, July 2003. | |||
[2] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, | [2] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, | |||
"Extended RTP Profile for Real-time Transport Control Protocol | "Extended RTP Profile for Real-time Transport Control Protocol | |||
(RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July 2006. | (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July 2006. | |||
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement | [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement | |||
Levels", BCP 14, RFC 2119, March 1997. | Levels", BCP 14, RFC 2119, March 1997. | |||
[4] Schooler, E., Ott, J., and J. Chesterfield, "RTCP Extensions | [4] Ott, J., Chesterfield, J., and E. Schooler, "RTP Control | |||
for Single-Source Multicast Sessions with Unicast Feedback", | Protocol (RTCP) Extensions for Single-Source Multicast Sessions | |||
draft-ietf-avt-rtcpssm-18 (work in progress), March 2009. | with Unicast Feedback", RFC 5760, February 2010. | |||
[5] Johansson, I. and M. Westerlund, "Support for Reduced-Size | [5] Johansson, I. and M. Westerlund, "Support for Reduced-Size | |||
Real-Time Transport Control Protocol (RTCP): Opportunities and | Real-Time Transport Control Protocol (RTCP): Opportunities and | |||
Consequences", RFC 5506, April 2009. | Consequences", RFC 5506, April 2009. | |||
[6] Singer, D. and H. Desineni, "A General Mechanism for RTP Header | [6] Singer, D. and H. Desineni, "A General Mechanism for RTP Header | |||
Extensions", RFC 5285, July 2008. | Extensions", RFC 5285, July 2008. | |||
[7] Mills, D., "Network Time Protocol (Version 3) Specification, | [7] Mills, D., "Network Time Protocol (Version 3) Specification, | |||
Implementation", RFC 1305, March 1992. | Implementation", RFC 1305, March 1992. | |||
[8] Schierl, T. and S. Wenger, "Signaling media decoding dependency | [8] Schierl, T. and S. Wenger, "Signaling Media Decoding Dependency | |||
in Session Description Protocol (SDP)", | in the Session Description Protocol (SDP)", RFC 5583, | |||
draft-ietf-mmusic-decoding-dependency-08 (work in progress), | July 2009. | |||
April 2009. | ||||
8.2. Informative References | 8.2. Informative References | |||
[9] Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis, "RTP | [9] Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis, "RTP | |||
Payload Format for SVC Video", draft-ietf-avt-rtp-svc-18 (work | Payload Format for SVC Video", draft-ietf-avt-rtp-svc-21 (work | |||
in progress), March 2009. | in progress), April 2010. | |||
[10] Lennox, J., Ott, J., and T. Schierl, "Source-Specific Media | [10] Lennox, J., Ott, J., and T. Schierl, "Source-Specific Media | |||
Attributes in the Session Description Protocol (SDP)", | Attributes in the Session Description Protocol (SDP)", | |||
draft-ietf-mmusic-sdp-source-attributes-02 (work in progress), | RFC 5576, June 2009. | |||
October 2008. | ||||
[11] Casner, S., "Session Description Protocol (SDP) Bandwidth | [11] Casner, S., "Session Description Protocol (SDP) Bandwidth | |||
Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC 3556, | Modifiers for RTP Control Protocol (RTCP) Bandwidth", RFC 3556, | |||
July 2003. | July 2003. | |||
[12] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A | [12] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A | |||
Protocol for Network Address Translator (NAT) Traversal for | Protocol for Network Address Translator (NAT) Traversal for | |||
Offer/Answer Protocols", draft-ietf-mmusic-ice-19 (work in | Offer/Answer Protocols", RFC 5245, April 2010. | |||
progress), October 2007. | ||||
[13] McGrew, D. and E. Rescorla, "Datagram Transport Layer Security | [13] McGrew, D. and E. Rescorla, "Datagram Transport Layer Security | |||
(DTLS) Extension to Establish Keys for Secure Real-time | (DTLS) Extension to Establish Keys for Secure Real-time | |||
Transport Protocol (SRTP)", draft-ietf-avt-dtls-srtp-05 (work | Transport Protocol (SRTP)", draft-ietf-avt-dtls-srtp-07 (work | |||
in progress), September 2008. | in progress), February 2009. | |||
[14] Zimmermann, P., Johnston, A., and J. Callas, "ZRTP: Media Path | [14] Zimmermann, P., Johnston, A., and J. Callas, "ZRTP: Media Path | |||
Key Agreement for Secure RTP", draft-zimmermann-avt-zrtp-13 | Key Agreement for Unicast Secure RTP", | |||
(work in progress), January 2009. | draft-zimmermann-avt-zrtp-18 (work in progress), April 2010. | |||
[15] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 5117, | [15] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 5117, | |||
January 2008. | January 2008. | |||
[16] Steeg, B., Begen, A., Caenegem, T., and Z. Vax, "Unicast-Based | [16] Steeg, B., Begen, A., Caenegem, T., and Z. Vax, "Unicast-Based | |||
Rapid Acquisition of Multicast RTP Sessions", | Rapid Acquisition of Multicast RTP Sessions", | |||
draft-ietf-avt-rapid-acquisition-for-rtp-05 (work in progress), | draft-ietf-avt-rapid-acquisition-for-rtp-09 (work in progress), | |||
November 2009. | April 2010. | |||
[17] Bont, F., Doehla, S., Schmidt, M., and R. Sperschneider, "RTP | [17] de Bont, F., Doehla, S., Schmidt, M., and R. Sperschneider, | |||
Payload Format for Elementary Streams with MPEG Surround multi- | "RTP Payload Format for Elementary Streams with MPEG Surround | |||
channel audio", draft-ietf-avt-rtp-mps-02 (work in progress), | Multi-Channel Audio", RFC 5691, October 2009. | |||
January 2009. | ||||
[18] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. | [18] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. | |||
Norrman, "The Secure Real-time Transport Protocol (SRTP)", | Norrman, "The Secure Real-time Transport Protocol (SRTP)", | |||
RFC 3711, March 2004. | RFC 3711, March 2004. | |||
Authors' Addresses | Authors' Addresses | |||
Colin Perkins | Colin Perkins | |||
University of Glasgow | University of Glasgow | |||
Department of Computing Science | Department of Computing Science | |||
End of changes. 13 change blocks. | ||||
87 lines changed or deleted | 79 lines changed or added | |||
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