Audio/Video Transport (avt)
---------------------------
Charter
Current status: active working group
Chair(s):
Stephen Casner <casner@isi.edu>
Transport Area Director(s):
Allison Mankin <mankin@isi.edu>
Mailing lists:
General Discussion:rem-conf@es.net
To Subscribe: rem-conf-request@es.net
Archive: nic.es.net:pub/mailing-lists/mail-archive/rem-conf
Description of Working Group:
The Audio/Video Transport Working Group was formed to specify
experimental protocols for real-time transmission of audio and
video over UDP and IP multicast. The focus of this group is
near-term and its purpose is to integrate and coordinate the
current AVT efforts of existing research activities. No
standards-track protocols are expected to be produced because
UDP transmission of audio and video is only sufficient for
small-scale experiments over fast portions of the Internet.
However, the transport protocols produced by this working group
should be useful on a larger scale in the future in conjunction
with additional protocols to access network-level resource
management mechanisms. Those mechanisms, research efforts now,
will provide low-delay service and guard against unfair consumption
of bandwidth by audio/video traffic.
Similarly, initial experiments can work without any connection
establishment procedure so long as a priori agreements on port
numbers and coding types have been made. To go beyond that, we
will need to address simple control protocols as well. Since IP
multicast traffic may be received by anyone, the control
protocols must handle authentication and key exchange so that the
audio/video data can be encrypted. More sophisticated connection
management is also the subject of current research. It is
expected that standards-track protocols integrating transport,
resource management, and connection management will be the result
of later working group efforts.
The AVT Working Group may design independent protocols specific to each
medium, or a common, lightweight, real-time transport protocol
may be extracted. Sequencing of packets and synchronization
among streams are important functions, so one issue is the form
of timestamps and/or sequence numbers to be used. The working group will
not focus on compression or coding algorithms which are domain of
higher layers.
Goals and Milestones:
Done Define the scope of the working group, and who might contribute.
The first step will be to solicit contributions of potential
protocols from projects that have already developed packet audio
and video. From these contributions the group will distill the
appropriate protocol features.
Done Conduct a teleconference working group meeting using a combination of
packet audio and telephone. The topic will be a discussion of issues
to be resolved in the process of synthesizing a new protocol.
Done Review contributions of existing protocols, and discuss which
features should be included and tradeoffs of different methods. Make
writing assignments for first-draft documents.
Done Post an Internet-Draft of the lightweight audio/video transport
protocol.
Done Post a revision of the AVT protocol addressing new work and security
options as an Internet-Draft.
Jun 93 Submit the AVT protocol to the IESG for consideration as an
Experimental Protocol.
Internet-Drafts:
Posted Revised I-D Title <Filename>
------ ------- ------------------------------------------
Dec 92 Nov 94 <draft-ietf-avt-rtp-06.txt>
RTP: A Transport Protocol for Real-Time Applications
Mar 93 Sep 94 <draft-ietf-avt-video-packet-03.txt>
Packetization of H.261 video streams
Mar 94 Nov 94 <draft-ietf-avt-cellb-profile-02.txt>
RTP Encapsulation of CellB Video Encoding
Nov 94 New <draft-ietf-avt-jpeg-00.txt>
RTP Encapsulation of JPEG-compressed video.
Request For Comments:
None to date.