Chroma quantization in video coding

摘要

A method of signaling additional chroma QP offset values that are specific to quantization groups is provided, in which each quantization group explicitly specifies its own set of chroma QP offset values. Alternatively, a table of possible sets of chroma QP offset values is specified in the header area of the picture, 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 specific chroma QP offset values are then used to determine the chroma QP values for blocks within the quantization group in addition to chroma QP offset values already specified for higher levels of the video coding hierarchy.

主权项

1. A method comprising:
identifying two or more initial sets of chroma quantization parameter (QP) offset values at two or more levels of a video coding hierarchy, each initial set of chroma QP offset values for specifying chroma QPs of video units encompassed by one level of the video coding hierarchy; identifying an additional set of chroma QP offset values for a quantization group comprising a plurality of video units; and for the plurality of video units, computing a set of chroma QP values by adding (i) the initial sets of chroma QP offset values that were identified for the plurality of video units and (ii) the additional set of chroma QP offset values that was identified for the quantization group.