Chroma quantization in video coding
摘要
說明書
In order to provide a video coding system in which chroma quantization parameters (QP) can be more flexibly specified, some embodiments of the invention provide a method of signaling additional chroma QP offset values that are specific to quantization groups. In some embodiments, each quantization group explicitly specifies its own set of chroma QP offset values. In some embodiments, a table of possible sets of chroma QP offset values is specified in the header area of the picture or the slice, and each quantization group uses an index to select an entry from the table for determining its own set of chroma QP offset values. The quantization group level chroma QP offset values are then used to determine the chroma QP values for blocks or sets of pixels within the quantization group. In some embodiments, the quantization group chroma QP values are used in conjunction with the luma QP of the block and the chroma QP offset values already specified at higher levels of the video coding hierarchy.
Some embodiments associate chroma QP offset specifications with quantization groups (QGs) that include one or more video data units. In some embodiments, each QG is associated with its own set of chroma QP offset specifications, and in some of these embodiments, the set of chroma QP offset specifications associated with a QG is encoded or embedded within the coding structure of a video data unit in the QG.
