Audio/Video Transport (avt) --------------------------- Charter Last Modified: 24-Oct-97 Current Status: Active Working Group Chair(s): Stephen Casner Transport Area Director(s): Scott Bradner Allyn Romanow Transport Area Advisor: Allyn Romanow Mailing Lists: General Discussion:rem-conf@es.net To Subscribe: rem-conf-request@es.net Archive: ftp://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 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 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 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 ------ ------- ------------------------------------------ Mar 96 Jun 97 RTP usage with Layered Multimedia Streams Apr 96 Sep 97 RTP Payload Format for H.263 Video Streams Aug 96 Feb 97 RTP Payload Format for Bundled MPEG Nov 96 Jul 97 Compressing IP/UDP/RTP Headers for Low-Speed Serial Links Nov 96 Jan 97 Alternatives for Enhancing RTCP Scalability Mar 97 New Real-Time Transport Protocol Management Information Base Mar 97 Jul 97 RTP Profile for Audio and Video Conferences with Minimal Control Apr 97 Jun 97 RTP Payload Format for MPEG1/MPEG2 Video Jul 97 New RTP Payload Format for QuickTime Media Streams Jul 97 New RTP Payload for DTMF Digits Aug 97 New An A/V Profile Extension for Generic Forward Error Correction in RTP Aug 97 New Options for Repair of Streaming Media Request For Comments: RFC Stat Published Title ------- -- ---------- ----------------------------------------- RFC1889 PS Jan 96 RTP: A Transport Protocol for Real-Time Applications RFC1890 PS Jan 96 RTP Profile for Audio and Video Conferences with Minimal Control RFC2035 PS Oct 96 RTP Payload Format for JPEG-compressed Video RFC2032 PS Oct 96 RTP payload format for H.261 video streams RFC2038 PS Oct 96 RTP Payload Format for MPEG1/MPEG2 Video RFC2029 PS Oct 96 RTP Payload Format of Sun's CellB Video Encoding RFC2190 PS Sep 97 RTP Payload Format for H.263 Video Streams RFC2198 PS Sep 97 RTP Payload for Redundant Audio Data