Audio/Video Transport (avt) --------------------------- Charter Chair(s): Stephen Casner Transport Area Director(s) Allison Mankin Mailing lists: General Discussion:rem-conf@es.net To Subscribe: rem-conf-request@es.net Archive: nic.es.net:~/ietf/rem-conf/av-transport-archive 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 AV transport 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. Our first step will be to solicit contributions of potential protocols from projects that have already developed packet audio and video. From these contributions we 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. May 93 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 ------ ------- ------------------------------------------ Oct 92 New Issues in Designing a Transport Protocol for Audio and Video Conferences and other Multiparticipant Real-Time Applications Dec 92 May 93 A Transport Protocol for Real-Time Applications Dec 92 New Media Encodings Dec 92 New Sample Profile for the Use of RTP for Audio and Video Conferences with Minimal Control Mar 93 New Packetization of H.261 video streams Request For Comments: None to date.