Audio/Video Transport (avt)

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: 2008-04-23

Additional information is available at tools.ietf.org/wg/avt

Chair(s):

Colin Perkins <csp@csperkins.org>

Roni Even <roni.even@polycom.co.il>

Tom Taylor <tom.taylor@rogers.com>

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

Jon Peterson <jon.peterson@neustar.biz>

Cullen Jennings <fluffy@cisco.com>

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:

Request For Comments:

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