FIG. 11 illustrates an example coding tree unit 1100 that can be in a quantization group that uses chroma QP offset values from a table in the picture header. The coding tree unit 1100 is described by pseudo code modified from the H.265 pseudo code in order to accommodate additional chroma QP offsets. The coding tree unit 1100 is in the quantization group 821 of the slice 811. The slice 811 is in the picture 802, whose header or PPS includes the table 890. The pseudo code for the coding tree unit 1100 is identical to the pseudo code for the coding tree unit 400 of FIG. 4, since in some embodiments, there is no difference between a coding tree unit in a quantization group that embeds chroma QP offset values explicitly and a coding tree unit in a quantization group that uses a set of chroma QP offset values from a table.
The pseudo code for the coding tree unit 1100 is illustrated with darkened lines 1111-1113, which are added for the purpose of determining whether the coding tree unit is part of a QG. Specifically, at line 1111, the parameter “additional_chroma_qp_offset” is used to indicate whether additional chroma information is allowed. The parameter “chroma_qp_offset_max_depth” is compared against a variable “l(fā)og 2CbSize” for determining whether the coding tree unit 1100 is in a chroma quantization group. For some embodiments, this also initializes the starting point of the chroma quantization group.
