draft-ietf-mmusic-decoding-dependency-04.txt   draft-ietf-mmusic-decoding-dependency-05.txt 
Network Working Group T. Schierl Network Working Group T. Schierl
Internet-Draft Fraunhofer HHI Internet-Draft Fraunhofer HHI
Intended status: Standards Track S. Wenger Intended status: Standards Track S. Wenger
Expires: April 20, 2009 Nokia Expires: May 19, 2009 Nokia
October 21, 2008 November 20, 2008
Signaling media decoding dependency in Session Description Protocol Signaling media decoding dependency in Session Description Protocol
(SDP) (SDP)
draft-ietf-mmusic-decoding-dependency-04 draft-ietf-mmusic-decoding-dependency-05
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
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have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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This Internet-Draft will expire on April 20, 2009. This Internet-Draft will expire on May 19, 2009.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
Abstract Abstract
This memo defines semantics that allow for signaling the decoding This memo defines semantics that allow for signaling the decoding
dependency of different media descriptions with the same media type in dependency of different media descriptions with the same media type in
the Session Description Protocol (SDP). This is required, for example, the Session Description Protocol (SDP). This is required, for example,
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4.2. Use cases ................................................... 8 4.2. Use cases ................................................... 8
5. Signaling Media Dependencies .................................. 8 5. Signaling Media Dependencies .................................. 8
5.1. Design Principles ........................................... 8 5.1. Design Principles ........................................... 8
5.2. Semantics ................................................... 9 5.2. Semantics ................................................... 9
5.2.1. SDP grouping semantics for decoding dependency ............ 9 5.2.1. SDP grouping semantics for decoding dependency ............ 9
5.2.2. "depend" attribute for dependency signaling per media-stream 5.2.2. "depend" attribute for dependency signaling per media-stream
................................................................... 9 ................................................................... 9
6. Usage of new semantics in SDP ................................ 11 6. Usage of new semantics in SDP ................................ 11
6.1. Usage with the SDP Offer/Answer Model ...................... 11 6.1. Usage with the SDP Offer/Answer Model ...................... 11
6.2. Declarative usage .......................................... 11 6.2. Declarative usage .......................................... 11
6.3. Usage with Capability Negotiation .......................... 11 6.3. Usage with AVP and SAVP RTP profiles ....................... 11
6.4. Examples ................................................... 12 6.4. Usage with Capability Negotiation .......................... 12
6.5. Examples ................................................... 12
7. Security Considerations ...................................... 14 7. Security Considerations ...................................... 14
8. IANA Considerations .......................................... 14 8. IANA Considerations .......................................... 14
9. Informative note on RFC 3388bis .............................. 15 9. Informative note on RFC 3388bis .............................. 15
10. References ................................................... 15 10. References ................................................... 15
10.1. Normative References ....................................... 15 10.1. Normative References ....................................... 16
10.2. Informative References ..................................... 16 10.2. Informative References ..................................... 16
Appendix A. Acknowledgements..................................... 16 Appendix A. Acknowledgements..................................... 17
Authors' Addresses................................................ 17 Authors' Addresses................................................ 17
Full Copyright Statement.......................................... 18 Full Copyright Statement.......................................... 18
Intellectual Property Statement................................... 18 Intellectual Property Statement................................... 18
1. Introduction 1. Introduction
An SDP session description may contain one or more media An SDP session description may contain one or more media
descriptions, each identifying a single media stream. A media descriptions, each identifying a single media stream. A media
description is identified by one "m=" line. Today, if more than one description is identified by one "m=" line. Today, if more than one
"m=" lines exist indicating the same media type, a receiver cannot "m=" lines exist indicating the same media type, a receiver cannot
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Operation Point of its choice. Operation Point of its choice.
If an RTSP receiver does not understand the signaling defined within If an RTSP receiver does not understand the signaling defined within
this memo, it falls back to normal SDP processing. Two likely cases this memo, it falls back to normal SDP processing. Two likely cases
have to be distinguished: (1) if at least one of the media types have to be distinguished: (1) if at least one of the media types
included in the SDP is within the receiver's capabilities, it selects included in the SDP is within the receiver's capabilities, it selects
among those candidates according to implementation specific criteria among those candidates according to implementation specific criteria
for setup, as usual. (2) If none of the media type included in the for setup, as usual. (2) If none of the media type included in the
SDP can be processed, then obviously no setup can occur. SDP can be processed, then obviously no setup can occur.
6.3. Usage with Capability Negotiation 6.3. Usage with AVP and SAVP RTP profiles
The signaling mechanisms defined in this draft MUST NOT be used to
negotiate between using AVP [RFC3551] and SAVP [RFC3711] profile for
RTP. But both profiles MAY be used separately or jointly with the
signaling mechanism defined in this draft.
6.4. Usage with Capability Negotiation
This memo does not cover the interaction with Capability Negotiation This memo does not cover the interaction with Capability Negotiation
[I-D.ietf-mmusic-sdp-capability-negotiation]. This issue is for [I-D.ietf-mmusic-sdp-capability-negotiation]. This issue is for
further study and will be addressed in a different memo. further study and will be addressed in a different memo.
6.4. Examples 6.5. Examples
a.) Example for signaling layered decoding dependency: a.) Example for signaling layered decoding dependency:
The example below shows a session description with three media The example below shows a session description with three media
descriptions, all of type video and with layered decoding descriptions, all of type video and with layered decoding
dependency ("lay"). Each of the media description includes two dependency ("lay"). Each of the media description includes two
possible media format descriptions with different encoding possible media format descriptions with different encoding
parameters as, e.g. "packetization-mode" (not shown in the parameters as, e.g. "packetization-mode" (not shown in the
example) for the media subtypes "H264" and "H264-SVC" given by example) for the media subtypes "H264" and "H264-SVC" given by
the "a=rtpmap:"-line. The first media description includes two the "a=rtpmap:"-line. The first media description includes two
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10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3388] Camarillo, G., Holler, J., and H. Schulzrinne, "Grouping of [RFC3388] Camarillo, G., Holler, J., and H. Schulzrinne, "Grouping of
Media Lines in the Session Description Protocol (SDP)", Media Lines in the Session Description Protocol (SDP)",
RFC 3388, December 2002. RFC 3388, December 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003. Applications", STD 64, RFC 3550, July 2003.
[RFC3551] Schulzrinne, H., and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551,
July 2003.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
[RFC4566] Handley, M., Jacobson, V, and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V, and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 5234, January 2008. Specifications: ABNF", RFC 5234, January 2008.
10.2. Informative References 10.2. Informative References
[I-D.ietf-avt-rtp-svc] [I-D.ietf-avt-rtp-svc]
Wenger, S., Wang Y.-K., T. Schierl and A. Eleftheriadis, Wenger, S., Wang Y.-K., T. Schierl and A. Eleftheriadis,
"RTP Payload Format for SVC Video", "RTP Payload Format for SVC Video",
draft-ietf-avt-rtp-svc-14 (work in progress), September draft-ietf-avt-rtp-svc-15 (work in progress), November
2008. 2008.
[I-D.ietf-mmusic-rfc3388bis] [I-D.ietf-mmusic-rfc3388bis]
Camarillo, G "The SDP (Session Description Protocol) Camarillo, G "The SDP (Session Description Protocol)
Grouping Framework", Grouping Framework",
draft-ietf-mmusic-rfc3388bis-01 (work in progress), July draft-ietf-mmusic-rfc3388bis-01 (work in progress), July
2008. 2008.
[I-D.ietf-mmusic-sdp-capability-negotiation] [I-D.ietf-mmusic-sdp-capability-negotiation]
Andreasen, F., "SDP Capability Negotiation", Andreasen, F., "SDP Capability Negotiation",
draft-ietf-mmusic-sdp-capability-negotiation-09, (work in draft-ietf-mmusic-sdp-capability-negotiation-09, (work in
progress), July 2008. progress), July 2008.
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