Chrominance Processing in High Efficiency Video Codecs

摘要

For 4:2:2 and 4:4:4 chroma-subsampling schemes, a high efficiency video coding system may implement several aspects of its encoding method differently to when using a 4:2:0 chroma ­subsampling scheme, in recognition of the greater amounts of chroma information retained in these schemes and the resulting changes to prediction unit and transform unit block structures. Consequently aspects of the present invention variously split a largest coding unit to a unit of 4x4 pixels, adapt coding unit tree structures, chroma transform unit block size selection, chroma intra-prediction mode angles, chroma intra­ prediction unit interpolation, chroma motion vector derivation, chroma spatial frequency transforms, so-called `cipprime' flags, chroma quantisation parameters, and chroma. quantisation matrices.