2.5.2 Audio/Video Transport (avt)

NOTE: This charter is a snapshot of the 72nd IETF Meeting in Dublin, Ireland. It may now be out-of-date.
In addition to this official charter maintained by the IETF Secretariat, there is additional information about this working group on the Web at:

       RTP FAQ Page

Last Modified: 2007-10-23

Chair(s):

Colin Perkins <csp@csperkins.org>
Tom Taylor <tom.taylor@rogers.com>
Roni Even <roni.even@polycom.co.il>

Real-time Applications and Infrastructure Area Director(s):

Jon Peterson <jon.peterson@neustar.biz>
Cullen Jennings <fluffy@cisco.com>

* The Real-time Applications and Infrastructure Area Directors were seated during the IETF 65.

Real-time Applications and Infrastructure Area Advisor:

Cullen Jennings <fluffy@cisco.com>

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:

  • draft-ietf-avt-rtcpssm-17.txt
  • draft-ietf-avt-rtp-jpeg2000-18.txt
  • draft-ietf-avt-profile-savpf-12.txt
  • draft-ietf-avt-rtp-atrac-family-15.txt
  • draft-ietf-avt-rfc2833biscas-05.txt
  • draft-ietf-avt-rtp-jpeg2000-beam-09.txt
  • draft-ietf-avt-rtp-hdrext-15.txt
  • draft-ietf-avt-smpte-rtp-12.txt
  • draft-ietf-avt-rfc3047-bis-05.txt
  • draft-ietf-avt-rtp-speex-05.txt
  • draft-ietf-avt-rtp-vorbis-09.txt
  • draft-ietf-avt-rtp-howto-03.txt
  • draft-ietf-avt-rtp-toffset-07.txt
  • draft-ietf-avt-avpf-ccm-10.txt
  • draft-ietf-avt-rtp-and-rtcp-mux-07.txt
  • draft-ietf-avt-rtcpxr-video-02.txt
  • draft-ietf-avt-rtp-svc-08.txt
  • draft-ietf-avt-rfc4695-bis-03.txt
  • draft-ietf-avt-rtp-evrc-wb-09.txt
  • draft-ietf-avt-rtcphr-03.txt
  • draft-ietf-avt-rtp-uemclip-04.txt
  • draft-ietf-avt-app-rtp-keepalive-02.txt
  • draft-ietf-avt-rtp-h264-params-01.txt
  • draft-ietf-avt-dtls-srtp-02.txt
  • draft-ietf-avt-rtcpxr-audio-01.txt
  • draft-ietf-avt-forward-shifted-red-01.txt
  • draft-ietf-avt-seed-srtp-01.txt
  • draft-ietf-avt-rtcp-non-compound-03.txt
  • draft-ietf-avt-rtp-h264-rcdo-00.txt
  • draft-ietf-avt-rfc4749-dtx-update-00.txt

    Request For Comments:

    RFCStatusTitle
    RFC1889 PS RTP: A Transport Protocol for Real-Time Applications
    RFC1890 PS RTP Profile for Audio and Video Conferences with Minimal Control
    RFC2029 PS RTP Payload Format of Sun's CellB Video Encoding
    RFC2032 PS RTP payload format for H.261 video streams
    RFC2035 PS RTP Payload Format for JPEG-compressed Video
    RFC2038 PS RTP Payload Format for MPEG1/MPEG2 Video
    RFC2190 PS RTP Payload Format for H.263 Video Streams
    RFC2198 PS RTP Payload for Redundant Audio Data
    RFC2250 PS RTP Payload Format for MPEG1/MPEG2 Video
    RFC2343 E RTP Payload Format for Bundled MPEG
    RFC2354 I Options for Repair of Streaming Media
    RFC2429 PS RTP Payload Format for the 1998 Version of ITU-T Rec. H.263 Video (H.263+)
    RFC2431 PS RTP Payload Format for BT.656 Video Encoding
    RFC2435 PS RTP Payload Format for JPEG-compressed Video
    RFC2508 PS Compressing IP/UDP/RTP Headers for Low-Speed Serial Links
    RFC2733 PS An RTP Payload Format for Generic Forward Error Correction
    RFC2736 BCP Guidelines for Writers of RTP Payload Format Specifications
    RFC2762 E Sampling of the Group Membership in RTP
    RFC2793 PS RTP Payload for Text Conversation
    RFC2833 PS RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals
    RFC2862 PS RTP Payload Format for Real-Time Pointers
    RFC2959 PS Real-Time Transport Protocol Management Information Base
    RFC3009 PS Registration of parityfec MIME types
    RFC3016 PS RTP payload format for MPEG-4 Audio/Visual streams
    RFC3047 PS RTP Payload Format for ITU-T Recommendation G.722.1
    RFC3119 PS A More Loss-Tolerant RTP Payload Format for MP3 Audio
    RFC3158 I RTP Testing Strategies
    RFC3189 PS RTP Payload Format for DV Format Video
    RFC3190 PS RTP Payload Format for 12-bit DAT, 20- and 24-bit Linear Sampled Audio
    RFC3267 PS RTP payload format and file storage format for the Adoptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) audio codecs
    RFC3389 PS RTP Payload for Comfort Noise
    RFC3497 PS RTP Payload Format for Society of Motion Picture and Television Engineers (SMPTE) 292M Video
    RFC3545 PS Enhanced Compressed RTP (CRTP) for links with High Delay,Packet Loss and Reordering
    RFC3550 DS RTP: A Transport Protocol for Real-Time Applications
    RFC3551 DS RTP Profile for Audio and Video Conferences with Minimal Control
    RFC3555 PS MIME Type Registration of RTP Payload Formats
    RFC3556 PS Session Description Protocol (SDP) Bandwidth Modifiers for RTP Control Protocol (RTCP) Bandwidth
    RFC3557 PS RTP Payload Format for European Telecommunications Standards Institute (ETSI) European Standard ES 201 108 Distributed Speech Recognition Encoding
    RFC3558 PS RTP Payload Format for Enhanced Variable Rate Codecs (EVRC) and Selectable Mode Vocoders SMV
    RFC3611 Standard RTP Control Protocol Extended Reports (RTCP XR)
    RFC3640 Standard RTP Payload Format for Transport of MPEG-4 Elementary Streams
    RFC3711 Standard The Secure Real-time Transport Protocol
    RFC3951 E Internet Low Bit Rate Codec
    RFC3952 E RTP Payload Format for iLBC Speech
    RFC3984 Standard RTP payload Format for H.264 Video
    RFC4040 Standard RTP payload format for a 64 kbit/s transparent call
    RFC4060 Standard 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
    RFC4102 Standard Registration of the text/red MIME Sub-Type
    RFC4103 Standard RTP Payload for Text Conversation
    RFC4170 BCP Tunneling Multiplexed Compressed RTP (TCRTP)
    RFC4175 Standard RTP Payload Format for Uncompressed Video
    RFC4184 Standard RTP Payload Format for AC-3 Audio
    RFC4247 I Requirements for Header Compression over MPLS
    RFC4298 Standard RTP Payload Format for BroadVoice Speech Codecs
    RFC4348 Standard Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Audio Codec
    RFC4351 H Real-Time Transport Protocol (RTP) Payload for Text Conversation Interleaved in an Audio Stream
    RFC4352 Standard RTP Payload Format for the Extended Adaptive Multi-Rate Wideband (AMR-WB+) Audio Codec
    RFC4396 Standard RTP Payload Format for 3rd Generation Partnership Project (3GPP) Timed Text
    RFC4421 Standard RTP Payload Format for Uncompressed Video: Additional Colour Sampling Modes
    RFC4424 PS Real-Time Transport Protocol (RTP) Payload Format for the Variable-Rate Multimode Wideband (VMR-WB) Extension Audio Codec
    RFC4425 PS RTP Payload Format for Video Codec 1 (VC-1)
    RFC4571 PS Framing Real-time Transport Protocol (RTP) and RTP Control Protocol (RTCP) Packets over Connection-Oriented Transport
    RFC4573 PS MIME Type Registration for RTP Payload Format for H.224
    RFC4585 PS Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)
    RFC4587 PS RTP Payload Format for H.261 Video Streams
    RFC4588 PS RTP Retransmission Payload Format
    RFC4598 PS Real-time Transport Protocol (RTP) Payload Format for Enhanced AC-3 (E-AC-3) Audio
    RFC4628 I RTP Payload Format for H.263 using RFC2190 to Historic status
    RFC4629 PS RTP Payload Format for ITU-T Rec. H.263 Video
    RFC4695 PS RTP Payload Format for MIDI
    RFC4696 I An Implementation Guide for RTP MIDI
    RFC4733 PS RTP Payload for DTMF Digits, Telephony Tones and Telephony Signals
    RFC4734 PS Definition of Events For Modem, FAX, and Text Telephony Signals
    RFC4749 PS RTP Payload Format for the G.729.1 Audio Codec
    RFC4788 PS Enhancements to RTP Payload Formats for EVRC Family Codecs
    RFC4855 PS Media Type Registration of RTP Payload Formats
    RFC4856 PS Media Type Registration of Payload Formats in the RTP Profile for Audio and Video Conferences
    RFC4867 PS RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs
    RFC4901 PS Protocol Extensions for Header Compression over MPLS
    RFC5109 PS RTP Payload Format for Generic Forward Error Correction
    RFC5117 I RTP Topologies
    RFC5219 PS A More Loss-Tolerant RTP Payload Format for MP3 Audio

    Meeting Minutes


    Slides

    Agenda
    RTP Payload Format for SVC
    Session Multiplexing for SVC Video
    RTP Payload Format for H.264
    Guidelines for Extending RTCP
    DTLS-SRTP Key Transport
    SRTP Store and Forward
    RTP Timestamps for Layered Encodings
    Why RTP does not mandate a single security mechanism
    RTP Payload Format for Geographic Location
    Rapid Synchronization with RTP Multicast Sessions
    Post-Repair Loss RLE Report Block Type for RTCP XR
    1-D Interleaved Parity FEC Scheme for FEC Framework
    RTCP HR
    Monitoring Architectures for RTP
    RTCP SSM security considerations