H.264 is a high compression digital video codec standard written by the ITU-T Video Coding Experts Group (VCEG) together with the ISO/IEC Moving Picture Experts Group (MPEG) as the product of a collective effort known as the Joint Video Team (JVT). This standard is identical to ISO MPEG-4 part 10, also known as AVC, for Advanced Video Coding. The final drafting work on the standard was completed in May of 2003.
H.264 is a name related to the ITU-T line of H.26x video standards, while AVC relates to its ISO MPEG roots. It is usual to call the standard as H.264/AVC, or AVC/H.264 to emphasize the common heritage. The name H.26L, also related to its ITU-T history, is far less common, but still used.
More recently, the JVT has been working on a corrigendum (a list of errata corrections) to the original standard. The drafting work on the corrigendum should be completed in May of 2004.
In addition, the JVT is nearing completion of the development of some extensions to the original standard that are known as the Fidelity Range Extensions. These extensions will support higher-fidelity video coding by supporting increased sample accuracy (including 10-bit and 12-bit coding) and higher-resolution color information (including sampling structures known as YUV 4:2:2 and YUV 4:4:4). Several other features are also included in the Fidelity Range Extensions project. The drafting work on the Fidelity Range Extensions should be completed in the Summer of 2004.
H.264 is already widely used for videoconferencing, including its support in products of the two main companies in that market (Polycom and Tandberg). It has also been preliminarily adopted as a mandatory part of the future DVD specification known as HD-DVD, now under development by the DVD Forum. A number of broadcasters in Japan and Korea have announced future support for the codec, and it is under consideration for other broadcast use -- for example, it is under consideration in the United States' Advanced Television Systems Committee (ATSC) and in Europe's Digital Video Broadcast (DVB) standards bodies. In the wireless world, it is under consideration for adoption by the 3rd-Generation Partnership Project (3GPP).
Like many ISO video standards, H.264/AVC has a reference implementation, that can be freely downloaded. Its main concern is to give examples of H.264/AVC features, instead of being a useful application per se.
A tweaked variant of this codec is implemented in the form of the Sorenson codec, as was found by an FFmpeg developer working on reverse-engineering the Sorenson codec.
Apple Computer is working on integrating H.264 into Tiger, the next version of Mac OS X.
External link
- H.264/MPEG-4 Part 10 Tutorials
- H.264/AVC Software Coordination
- ftp.imtc-files.org/jvt-experts FTP site for reference implementation history as well as expert meetings