ITU and MPEG Particpants,

Two days ago I sent a message noting the achievement of H.263 compatibility in MPEG-4 video. I want to clarify one aspect of that message. In my exuberance over the outcome of the Tokyo MPEG meeting, I may have glossed over describing the precise resulting technical relationship between the two standards. This was pointed out to me in a private email message.

To clarify, the MPEG-4 video syntax was altered in Tokyo so that an MPEG-4 video decoder can decode H.263 Baseline bitstreams. However, since the MPEG-4 video syntax can also support additional features not supported in H.263 Baseline syntax, the opposite is not true in general -- not all MPEG-4 video streams can be decoded by H.263 Baseline decoders. (This is probably understood by those of us who have intimate knowledge of these standards, but may need to be clarified for others.)

Best Wishes,

Gary Sullivan

---------------------------------------------- From: Gary Sullivan garys@pictel.com Subject: MPEG-4 Compatibility with ITU-T H.263

In Re: Compatibility between MPEG-4 Video and ITU-T Rec. H.263:

I wish to take note of what I believe to be an important milestone in video coding standardization. Last week, the MPEG-4 project achieved compatibility with ITU-T H.263.

MPEG created a "final committee draft" of its draft MPEG-4 video coding standard last week (March 16-20) at its 43rd meeting in Tokyo. Full compatibility with the prior video coding standard ITU-T Recommendation H.263 was adopted into that draft. The compatibility was achieved by an alignment of complete syntax support for the primary "Baseline" interoperability operational mode of Rec. H.263. This is an important event in video coding standardization development, ensuring that the new implementations of the future MPEG-4 video standard (FCD for ISO/IEC 14496-2) can have full compatibility with the deployed implementations of Rec. H.263 worldwide. This action sends a clear message that H.263 technology remains at the heart of today's understanding of low bit-rate video compression coding, and that interoperability of these standardized systems is needed world-wide.

ITU-T Recommendation H.263 is a video coding standard developed by the International Telecommunications Union (Telecommunications Standardization Sector, formerly CCITT). It was originally approved in November of 1995 and is maintained by the ITU-T Advanced Video Coding Experts Group, formally chartered as Question 15 of the ITU-T Study Group 16 for Multimedia Standardization. Newly approved in a second-generation specification completed in September of 1997 and approved in January of 1998, Rec. H.263 is the current "flagship" ITU standard for low bit rate video communication coding. The "Baseline" mode which forms the heart of H.263 operation was the fundamental requirement for all implementations of the original H.263 specification and is now also fully supported in both the second version of H.263 and in the new draft of MPEG-4 video. The H.263 Baseline mode provides an excellent interoperable common core for video coding systems.

MPEG-4 video, to be formalized in ISO/IEC 14496-2, is a project of the Moving Picture Experts Group (MPEG) formally chartered as Working Group 11 of ISO/IEC JTC1 SC29. The MPEG-4 video coding standardization project is developing its specification to provide a broadly-applicable and flexible set of video coding tools and defined configuration profiles for a wide range of multimedia applications with new functionalities such as object-segmented coding and the handling of hybrids of natural and synthetic content. The first of two planned versions of MPEG-4 video is now in a "final committee draft" stage and is expected to receive final approval in December of 1998.

I want to thank those who helped bring about this important convergence of standardization development. In particular I would like to thank the MPEG convenor Mr. Leonardo Chiariglione, the MPEG Video chairman Mr. Thomas Sikora, the MPEG Video Coding Efficiency chairman Mr. T. K. Tan, and the supporting MPEG National Bodies of Canada, France, Norway, and the Netherlands. I also wish to especially thank those individuals who recently actively contributed toward the final detailed technical evaluation, proposal, and drafting process for this effort, in particular especially Ms. Gunn Kristin Klungsoyr, Mr. Cor Quist, Mr. Aasmand Sandvand, Mr. Peter List, and Ms. Cecille Dufour. I also wish to thank those who contributed toward this goal previously at critical moments, in partular Mr. Robert Danielsen, Mr. Tom-Ivar Johansen, Mr. Richard Schaphorst, Prof. Faouzi Kossentini, and Mr. Jan De Lameillieure.

Sincerely,

Gary Sullivan ITU-T Advanced Video Coding Rapporteur PictureTel Corporation

This is not an official statement of PictureTel or of ITU-T Q15/SG16.