Chroma quantization in video coding
摘要
說(shuō)明書(shū)
At 730, the process determines whether it has reached the start of a chroma quantization group. In some embodiments, the process examines whether it is at the level of the video hierarchy that has been identified as a chroma quantization group. If the process is not at the start of a chroma quantization group (e.g., is already inside a chroma quantization group), the process proceeds to 750. If the process is at the start of a chroma quantization group, the process proceeds to 740. Examples of operations 720 and 730 are discussed by reference to
At 740, the process identifies the chroma QP offset values for the chroma quantization group. In some embodiments, chroma QP offsets are encoded explicitly within the chroma quantization groups as discussed above by reference to
The process then identifies (at 750) luma QP value(s) for the chroma quantization group. As mentioned, in some embodiments, luma QP values are set according to luma quantization groups, which may or may not be the same as chroma quantization groups. Depending on signaling, there can be more or fewer luma quantization groups than chroma quantization groups. In some embodiments, a luma quantization group may contain multiple chroma quantization groups or vice versa. In some embodiments, chroma quantization groups and luma quantization groups may overlap each other. Consequently, different coding units in the same chroma quantization group may have different luma QP values based on luma quantization groups.
