Context Adaptive Variable Length Coding

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Context Adaptive Variable Length Coding ( CAVLC , German: Context Adaptive Code of Variable Length) describes a context-dependent run length coding and is a type of lossless entropy coding . CAVLC is used for video compression MPEG-4 / Part 10 ( H.264 / AVC). The CAVLC was designed in such a way that it can use as many peculiarities of MPEG quantization as possible. Features of MPEG quantization include:

  • The initial set mainly contains zeros,
  • the highest values ​​are at the beginning of the initial quantity and become lower and at the end
  • the highest values ​​in the initial set are often sequences of 1 and −1.

A data stream compressed with CAVLC is around 10-20% larger than a data stream compressed with the more computationally intensive Context-Adaptive Binary Arithmetic Coding (CABAC).

literature

  • Iain EG Richardson: H.264 and MPEG-4 Video Compression: Video Coding for Next-generation Multimedia . John Wiley & Sons Ltd., Chichester 2003.

Web links