Once the set of chroma QP offset values has been identified from the table 890, the computation of chroma quantization parameters is similar to that of FIG. 1. In the example of FIG. 8, the luma QP values 851 (from four luma QGs overlapping the chroma QG 821) are applicable to the chroma QG 821, the luma QP value 852 (from a same luma QG) is applicable to the chroma QG 822, and the luma QP values 853 (from two luma QGs overlapping the chroma QG 823) is applicable to QG 823. Adding the luma QP values 851, the chroma QP offset 831 (for the picture 802 and/or for slice 811), and the chroma QP offset C (retrieved from table entry 893 for QG 821) yields chroma QP values 861 for the QG 821. Adding the luma QP values 852, the chroma QP offset 831, and the chroma QP offset A (retrieved from table entry 891) yields chroma QP values 862 for the QG 822. Adding the luma QP values 853, the chroma QP offset 831, and the chroma QP offset A (retrieved from table entry 891) yields chroma QP values 863 for the QG 823.
In some embodiments, the table of chroma QP offsets is encoded within the header area of an encoded video picture. FIG. 9 illustrates an example picture header or PPS 900 that encodes the table 890. The picture header 900 is described by pseudo code that is modified from the H.265 standard in order to accommodate additional chroma QP offsets.
