A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Audio/Video Transport Working Group of the IETF.

Title : RTP Payload Format for the 1998 Version of ITU-T Rec. H.263 Video (H.263+) Author(s) : C. Maciocco, J. Ott, C. Bormann, C. Zhu, L. Cline, D.Newell, G. Sullivan, G.Deisher, S. Wenger Filename : draft-ietf-avt-rtp-h263-video-01.txt Pages : 10 Date : 14-Jan-98

This document specifies an RTP payload header format applicable to the transmission of video streams generated based on the 1998 version of ITU-T Recommendation H.263 [4]. Because the 1998 version of H.263 is a superset of the 1996 syntax, this format can also be used with the 1996 version of H.263.

The 1998 version of ITU-T Recommendation H.263 added numerous coding options to improve codec performance over the 1996 version. The 1998 version is referred to as H.263+ in this document. Among the new options, the ones with the biggest impact on the RTP payload specification and the error resilience of the video content are the slice structured mode, the independent segment decoding mode (ISD), the reference picture selection mode, and the scalability mode. This section summarizes the impact of these new coding options on packetization. Refer to [4] for more information on coding options.

The slice structured mode was added to H.263+ for three purposes: to provide enhanced error resilience capability, to make the bitstream more amenable to use with an underlying packet transport such as RTP, and to minimize video delay. The slice structured mode supports fragmentation at macroblock boundaries.

With the independent segment decoding option, a video picture frame is broken into segments and encoded in such a way that each segment is independently decodable. Utilizing ISD in a lossy network environment helps to prevent the propagation of errors from one segment of the picture to others.

The reference picture selection mode allows the use of an older reference picture rather than the one immediately preceding the current picture. Usually, the last transmitted frame is implicitly used as the reference picture for inter-frame prediction. If the reference picture selection mode is used, the data stream carries information on what reference frame should be used, indicated by the temporal reference as an ID for that reference fra

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