Advanced Video Coding: Difference between revisions

Revision as of 10:33, 26 September 2004

Revision as of 10:41, 26 September 2004

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The intents of H.264/AVC project were to create a standard that would lead to fast implementations, using low bitrates. That is: implementations that would demand little from the decoder hardware and from the network bandwidth.

H.264/AVC contains several innovative, useful new features that allow it to compress video much more effectively than older codecs. CABAC (Context-Adaptive Binary Arithmetic Coding) is a clever technique that can be used in H.264 to losslessly compress syntax elements in the video stream. ItH.264 also implements an in-loop deblocking filter which canhelps prevent the ringing and blocking artifacts that are common to other [[DCT]]-based image compression techniques. In previous video standards, [[motion compensation]] is handled by allowing blocks in a frame to refer only to the frame before it. H.264/AVC allows theframes possibilityto ofbe predicting new framespredicted from other frames that are arbitrarily far in the past. This usually allows modest improvements in bitrate and quality in most scenes. But (for example) in rapidlycertain flashingtypes of scenes with rapid repetitive flashing, it allows a massive reduction in bitrate. These ideas, along with many other new ideas, help H.264 to perform significantly better than MPEG-4 ASP can. H.264 can usually perform radically better than [[MPEG-2]] at a fraction of the bitrate.

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.