Audio/Video Transport (avt) --------------------------- Charter Last Modified: 2007-10-23 Current Status: Active Working Group Chair(s): Colin Perkins Roni Even Tom Taylor Real-time Applications and Infrastructure Area Director(s): Jon Peterson Cullen Jennings Real-time Applications and Infrastructure Area Advisor: Cullen Jennings Mailing Lists: General Discussion:avt@ietf.org To Subscribe: https://www1.ietf.org/mailman//listinfo/avt Archive: http://www.ietf.org/mail-archive/web/avt/index.html Description of Working Group: The Audio/Video Transport Working Group was formed to specify a protocol for real-time transmission of audio and video over unicast and multicast UDP/IP. This is the Real-time Transport Protocol, RTP, together with its associated profiles and payload formats. The current aims of the working group are: - to review and revise existing payload formats to advance those which are useful to Draft Standard, and to declare others as Historic. Milestones will be established as a champion for each payload format is identified. - to develop payload formats for new media codecs, and to document best-current practices in payload format design. The group continues to be precluded from work on codecs themselves because of overlap with the other standards bodies, and because the IETF does not have the ability to effectively review new codecs. An exception was made for the freeware iLBC codec on a highly experimental basis, but acceptance of new codec work is unexpected and subject to rechartering. - to complete the forward error correction work to update RFC 2733 in the form of the ULP payload format - to extend RTP to work with Source-Specific Multicast sessions with unicast feedback - to provide a framing mechanism for RTP over TCP and TLS - in collaboration with the MPLS and ROHC WGs, to develop a solution for header compression of RTP across MPLS networks that avoid decompression and compression at each MPLS node. - to develop a new RTP profile for the combination of the SRTP profile and the Extended RTP Profile for RTCP-based Feedback (RTP/SAVPF) - to maintain and enhance the SRTP Profile, with review and input from the Security Area - to develop a new RTP profile for usage of TFRC (RFC 3448) with RTP over UDP to allow application developers to gain experience with TCP friendly congestion control. - to develop a MIB for RTCP XR (RFC 3611). - to update the RTP MIB, including aligning it with RFC 3550. - to clarify how RTP is used for media in conferencing with centralised nodes performing relay, translation or mixing of media. - to develop the mechanisms needed for efficient control of media and its encoding process in RTP based conferencing, both over multicast and transport containing relays, translators and mixers. An example of such a mechanism is a method to request a full intra coded frame of video. This would be used to allow joining participants to receive video immediately after joining instead of waiting for the next intra coded frame. It also allows mixers to perform switching between media sources without the need to re-encode the media. - to develop a solution for carrying media meta data, specifically SMPTE timestamps, to enhance the media stream. Such transport may be done in either RTP or RTCP depending on which is most suitable. The WG may consider if a generalized mechanism should be developed to enable future types of meta data to be easier to include. - to develop two new metric blocks for the RTCP XR (RFC 3611) framework to provide information on the media quality experienced by the receiver of RTP flows. One metrics block is for high resolution measurements of audio and speech quality. A second one for providing information on the quality of video. The timescale to complete this second block and the included metrics are highly dependable on the development of standardized subjective metrics for video quality. The WG will consider what metrics that are available and if they should be included or not. The metrics blocks shall not duplicate signalling information anyway necessary for the establishment of the session. - to specify how the RFC 3550 requirement on RTCP senders to always send compound packets can be relaxed to allow for non-compound packets. The specification need to define under which criteria non-compound RTCP packets may be sent while maintaining the functionality that motivated the usage of compound RTCP packets and keep the bandwidth within specified limits. The longer term goals of the working group are to advance the SRTP Profile, the Extended RTP Profile for RTCP-based Feedback, the Compressed RTP framework, and the RTP MIB to Draft Standard. The group has no plans to develop new RTP profiles beyond those listed above, but will consider rechartering to produce profile level extensions if appropriate. Goals and Milestones: Done Review DCCP including prototypes and API; feedback to DCCP WG Done Initial draft requirements for ECRTP over MPLS; discuss with MPLS WG Done Submit iLBC payload format for Proposed Standard Done Submit iLBC codec specification for Experimental Done Advance RTP specification and A/V profile to Full Standard Done Submit RTP/SAVPF profile for Proposed Standard Done Finished investigation of advanced FEC codes for RTP, update plan Done Submit ULP Payload Format for Proposed Standard Feb 2007 Submit Codec Control Messages for Proposed Standard Done Submit SMTPE Timestamping of Media for Proposed Standard Mar 2007 Submit SRTP for Draft Standard Mar 2007 Submit RTCP XR Video Metrics block for Proposed Standard Done Submit Multiplexing of RTCP and RTP on the same port for Proposed Standard Apr 2007 Submit RTCP/SSM draft for Proposed Standard Jul 2007 Submit update of RTP MIB for Proposed or Draft Standard Done Submit draft on Enhancing RTP header extensions for proposed standard Aug 2007 Submit RTCP XR MIB for Proposed Standard Aug 2007 Submit RTCP XR High Resolution Audio Metrics for Proposed Standard Sep 2007 Submit RTP/AVPF for Draft Standard Dec 2007 Submit in band keying mechanism for SRTP draft for Proposed Standard Feb 2008 Submit draft on Mechanisms to keep NAT bindings for RTP flows alive for BCP Sep 2008 Submit Non-Compound usage specification for PS Internet-Drafts: Posted Revised I-D Title ------ ------- -------------------------------------------- Nov 2000 Aug 2007 RTP Payload Format for Generic Forward Error Correction Feb 2002 Nov 2007 RTCP Extensions for Single-Source Multicast Sessions with Unicast Feedback May 2002 Sep 2007 RTP Payload Format for JPEG 2000 Video Streams Oct 2002 Aug 2007 A More Loss-Tolerant RTP Payload Format for MP3 Audio Oct 2003 Nov 2007 Extended Secure RTP Profile for RTCP-based Feedback (RTP/SAVPF) Jun 2004 Jul 2007 RTP with TCP Friendly Rate Control Aug 2004 Aug 2007 RTP Payload Format for Adaptive TRansform Acoustic Coding (ATRAC) Family Feb 2005 Jun 2007 Definition of Events For Channel-Oriented Telephony Signalling Feb 2005 Sep 2007 Payload Format for JPEG 2000 Video: Extensions for Scalability and Main Header Recovery May 2005 May 2007 A No-Op Payload Format for RTP Aug 2005 Aug 2007 A general mechanism for RTP Header Extensions Aug 2005 Aug 2007 Associating Time-codes with RTP streams Aug 2005 Nov 2007 RTP Payload Format for ITU-T Recommendation G.722.1 Oct 2005 Jul 2007 RTP Payload Format for the Speex Codec Feb 2006 Nov 2007 RTP Payload Format for Vorbis Encoded Audio May 2006 Jul 2007 How to Write an RTP Payload Format Aug 2006 Aug 2007 Transmission Time offsets in RTP streams Aug 2006 Oct 2007 Codec Control Messages in the RTP Audio-Visual Profile with Feedback (AVPF) Aug 2006 Oct 2007 RTP Topologies Oct 2006 Aug 2007 Multiplexing RTP Data and Control Packets on a Single Port Dec 2006 Nov 2007 RTCP XR - Video Metrics Report Blocks Dec 2006 Nov 2007 RTP Payload Format for SVC Video Jan 2007 Aug 2007 RTP Payload Format for MIDI Jan 2007 Nov 2007 RTP payload format for Enhanced Variable Rate Wideband Codec (EVRC-WB) and media subtype updates for EVRC-B codec Feb 2007 Nov 2007 RTCP HR - High Resolution VoIP Metrics Report Blocks May 2007 Nov 2007 RTP payload format for UEMCLIP speech codec Jun 2007 Jun 2007 Application Mechanism for maintaining alive the Network Address Translator (NAT) mappings associated to RTP flows. Jul 2007 Jul 2007 Parameters for Static Macroblocks and Aspect Ratio in the RTP Payload Format for H.264 Video Jul 2007 Nov 2007 Datagram Transport Layer Security (DTLS) Extension to Establish Keys for Secure Real-time Transport Protocol (SRTP) Jul 2007 Nov 2007 RTCP XR - Audio Metrics Report Block Jul 2007 Jul 2007 RTCP XR - MPEG Transport Metrics Report Block Sep 2007 Sep 2007 Forward-shifted RTP Redundancy Payload Support Oct 2007 Oct 2007 The SEED Cipher Algorithm and Its Use with the Secure Real-time Transport Protocol (SRTP) Request For Comments: RFC Stat Published Title ------- -- ----------- ------------------------------------ RFC1889 PS Jan 1996 RTP: A Transport Protocol for Real-Time Applications RFC1890 PS Jan 1996 RTP Profile for Audio and Video Conferences with Minimal Control RFC2035 PS Oct 1996 RTP Payload Format for JPEG-compressed Video RFC2032 PS Oct 1996 RTP payload format for H.261 video streams RFC2038 PS Oct 1996 RTP Payload Format for MPEG1/MPEG2 Video RFC2029 PS Oct 1996 RTP Payload Format of Sun's CellB Video Encoding RFC2190 PS Sep 1997 RTP Payload Format for H.263 Video Streams RFC2198 PS Sep 1997 RTP Payload for Redundant Audio Data RFC2250 PS Jan 1998 RTP Payload Format for MPEG1/MPEG2 Video RFC2343 E May 1998 RTP Payload Format for Bundled MPEG RFC2354 I Jun 1998 Options for Repair of Streaming Media RFC2429 PS Oct 1998 RTP Payload Format for the 1998 Version of ITU-T Rec. H.263 Video (H.263+) RFC2431 PS Oct 1998 RTP Payload Format for BT.656 Video Encoding RFC2435 PS Oct 1998 RTP Payload Format for JPEG-compressed Video RFC2508 PS Feb 1999 Compressing IP/UDP/RTP Headers for Low-Speed Serial Links RFC2733 PS Dec 1999 An RTP Payload Format for Generic Forward Error Correction RFC2736BCP Dec 1999 Guidelines for Writers of RTP Payload Format Specifications RFC2762 E Feb 2000 Sampling of the Group Membership in RTP RFC2833 PS Jun 2000 RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals RFC2793 PS Jun 2000 RTP Payload for Text Conversation RFC2862 PS Jul 2000 RTP Payload Format for Real-Time Pointers RFC2959 PS Oct 2000 Real-Time Transport Protocol Management Information Base RFC3009 PS Dec 2000 Registration of parityfec MIME types RFC3016 PS Dec 2000 RTP payload format for MPEG-4 Audio/Visual streams RFC3047 PS Feb 2001 RTP Payload Format for ITU-T Recommendation G.722.1 RFC3119 PS Jun 2001 A More Loss-Tolerant RTP Payload Format for MP3 Audio RFC3158 I Aug 2001 RTP Testing Strategies RFC3189 PS Jan 2002 RTP Payload Format for DV Format Video RFC3190 PS Jan 2002 RTP Payload Format for 12-bit DAT, 20- and 24-bit Linear Sampled Audio RFC3267 PS Jul 2002 RTP payload format and file storage format for the Adoptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) audio codecs RFC3389 PS Oct 2002 RTP Payload for Comfort Noise RFC3497 PS Mar 2003 RTP Payload Format for Society of Motion Picture and Television Engineers (SMPTE) 292M Video RFC3550 DS Jul 2003 RTP: A Transport Protocol for Real-Time Applications RFC3551 DS Jul 2003 RTP Profile for Audio and Video Conferences with Minimal Control RFC3555 PS Jul 2003 MIME Type Registration of RTP Payload Formats RFC3556 PS Jul 2003 Session Description Protocol (SDP) Bandwidth Modifiers for RTP Control Protocol (RTCP) Bandwidth RFC3557 PS Jul 2003 RTP Payload Format for European Telecommunications Standards Institute (ETSI) European Standard ES 201 108 Distributed Speech Recognition Encoding RFC3558 PS Jul 2003 RTP Payload Format for Enhanced Variable Rate Codecs (EVRC) and Selectable Mode Vocoders SMV RFC3545 PS Jul 2003 Enhanced Compressed RTP (CRTP) for links with High Delay,Packet Loss and Reordering RFC3611Standard Nov 2003 RTP Control Protocol Extended Reports (RTCP XR) RFC3640Standard Dec 2003 RTP Payload Format for Transport of MPEG-4 Elementary Streams RFC3711Standard Mar 2004 The Secure Real-time Transport Protocol RFC3951 E Dec 2004 Internet Low Bit Rate Codec RFC3952 E Dec 2004 RTP Payload Format for iLBC Speech RFC3984Standard Feb 2005 RTP payload Format for H.264 Video RFC4040Standard Apr 2005 RTP payload format for a 64 kbit/s transparent call RFC4060Standard May 2005 RTP Payload Formats for European Telecommunications Standardsv Institute (ETSI) European Standard ES 202 050, ES 202 211, and ES 202 212 Distributed Speech Recognition Encoding RFC4102Standard Jun 2005 Registration of the text/red MIME Sub-Type RFC4103Standard Jun 2005 RTP Payload for Text Conversation RFC4175Standard Sep 2005 RTP Payload Format for Uncompressed Video RFC4184Standard Oct 2005 RTP Payload Format for AC-3 Audio RFC4247 I Nov 2005 Requirements for Header Compression over MPLS RFC4170BCP Nov 2005 Tunneling Multiplexed Compressed RTP (TCRTP) RFC4298Standard Dec 2005 RTP Payload Format for BroadVoice Speech Codecs RFC4348Standard Jan 2006 Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Audio Codec RFC4351 H Jan 2006 Real-Time Transport Protocol (RTP) Payload for Text Conversation Interleaved in an Audio Stream RFC4352Standard Jan 2006 RTP Payload Format for the Extended Adaptive Multi-Rate Wideband (AMR-WB+) Audio Codec RFC4396Standard Feb 2006 RTP Payload Format for 3rd Generation Partnership Project (3GPP) Timed Text RFC4425 PS Feb 2006 RTP Payload Format for Video Codec 1 (VC-1) RFC4421Standard Feb 2006 RTP Payload Format for Uncompressed Video: Additional Colour Sampling Modes RFC4424 PS Feb 2006 Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Extension Audio Codec RFC4573 PS Jul 2006 MIME Type Registration for RTP Payload Format for H.224 RFC4585 PS Jul 2006 Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF) RFC4571 PS Jul 2006 Framing Real-time Transport Protocol (RTP) and RTP Control Protocol (RTCP) Packets over Connection-Oriented Transport RFC4588 PS Jul 2006 RTP Retransmission Payload Format RFC4598 PS Jul 2006 Real-time Transport Protocol (RTP) Payload Format for Enhanced AC-3 (E-AC-3) Audio RFC4587 PS Aug 2006 RTP Payload Format for H.261 Video Streams RFC4749 PS Oct 2006 RTP Payload Format for the G.729.1 Audio Codec RFC4695 PS Nov 2006 RTP Payload Format for MIDI RFC4696 I Nov 2006 An Implementation Guide for RTP MIDI RFC4734 PS Dec 2006 Definition of Events For Modem, FAX, and Text Telephony Signals RFC4733 PS Dec 2006 RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals RFC4788 PS Jan 2007 Enhancements to RTP Payload Formats for EVRC Family Codecs RFC4629 PS Jan 2007 RTP Payload Format for ITU-T Rec. H.263 Video RFC4628 I Feb 2007 RTP Payload Format for H.263 using RFC2190 to Historic status RFC4855 PS Feb 2007 Media Type Registration of RTP Payload Formats RFC4856 PS Feb 2007 Media Type Registration of Payload Formats in the RTP Profile for Audio and Video Conferences RFC4867 PS Apr 2007 RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs RFC4901 PS Jun 2007 Protocol Extensions for Header Compression over MPLS