Using quantization groups in video coding

1. A method of processing video data, comprising:

applying, in a conversion between a video comprising multiple color components and a bitstream of the video, a deblocking filter to video blocks of the multiple color components;

performing the conversion based on the applying,

wherein a deblocking filter strength for the deblocking filter of the video blocks of each of the multiple color components is determined according to a rule;

wherein the rule specifies to use a different manner for determining the deblocking filter strength for the video blocks of each of the multiple color components;

wherein the multiple color components comprise at least a Cb component and a Cr component; and wherein each of the multiple color components is associated with deblocking parameter offsets for a variable beta and a variable tC in different video unit levels which are used to determine the deblocking filter strength; and

wherein the different video unit levels comprise a picture parameter set (PPS), wherein a first syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the PPS is pps_cb_beta_offset_div2 and a first syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in PPS is pps_cr_beta_offset_div2; and wherein a second syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in PPS is pps_cb_tc_offset_div2 and a second syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the PPS is pps_cr_tc_offset_div2.

2. The method of claim 1 , wherein pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify default deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in slice headers of the slices referring to the PPS; and

wherein pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify default deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cr component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the slice headers of the slices referring to the PPS.

3. The method of claim 1 , wherein the different video unit levels comprise a picture header, wherein a third syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the picture header is pic_cb_beta_offset_div2 and a third syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the picture header is pic_cr_beta_offset_div2; and a fourth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the picture header is pic_cb_tc_offset_div2 and a fourth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the picture header is pic_cr_tc_offset_div2.

4. The method of claim 3 , wherein pic_cb_beta_offset_div2 and pic_cb_tc_offset_div2 specify deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for slices associated with the picture header; and

wherein pic_cr_beta_offset_div2 and pic_cr_tc_offset_div2 specify deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cr component for the slices associated with the picture header.

5. The method of claim 1 , wherein the different video unit levels comprise a slice header, wherein a fifth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the slice header is slice_cb_beta_offset_div2 and a fifth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the slice header is slice_cr_beta_offset_div2; and a sixth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the slice header is slice_cb_tc_offset_div2 and a sixth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the slice header is slice_cr_tc_offset_div2.

6. The method of claim 5 , wherein slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify the deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for a current slice; and

wherein slice_cr_beta_offset_div2 and slice_cr_tc_offset_div2 specify the deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for the current slice.

7. The method of claim 1 , wherein the conversion includes encoding the video into the bitstream.

8. The method of claim 1 , wherein the conversion includes decoding the video from the bitstream.

9. An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:

apply, in a conversion between a video comprising multiple color components and a bitstream of the video, a deblocking filter to video blocks of the multiple color components; and

perform the conversion based on the applied deblocking filter,

wherein a deblocking filter strength for the deblocking filter of the video blocks of each of the multiple color components is determined according to a rule;

wherein the rule specifies to use a different manner for determining the deblocking filter strength for the video blocks of each of the multiple color components;

wherein the multiple color components comprise at least a Cb component and a Cr component; and wherein each of the multiple color components is associated with deblocking parameter offsets for a variable beta and a variable tC in different video unit levels which are used to determine the deblocking filter strength; and

wherein the different video unit levels comprise a picture parameter set (PPS), wherein a first syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the PPS is pps_cb_beta_offset_div2 and a first syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the PPS is pps_cr_beta_offset_div2; and a second syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the PPS is pps_cb_tc_offset_div2 and a second syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the PPS is pps_cr_tc_offset_div2.

10. The apparatus of claim 9 ,

wherein pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify default deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in slice headers of the slices referring to the PPS; and

wherein pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify default deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cr component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the slice headers of the slices referring to the PPS.

11. The apparatus of claim 9 , wherein the different video unit levels comprise a picture header, wherein a third syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the picture header is pic_cb_beta_offset_div2 and a third syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the picture header is pic_cr_beta_offset_div2; and a fourth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the picture header is pic_cb_tc_offset_div2 and a fourth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the picture header is pic_cr_tc_offset_div2;

wherein pic_cb_beta_offset_div2 and pic_cb_tc_offset_div2 specify deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for slices associated with the picture header; and

wherein pic_cr_beta_offset_div2 and pic_cr_tc_offset_div2 specify deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cr component for the slices associated with the picture header.

12. The apparatus of claim 9 , wherein the different video unit levels comprise a slice header, wherein a fifth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the slice header is slice_cb_beta_offset_div2 and a fifth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the slice header is slice_cr_beta_offset_div2; and a sixth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the slice header is slice_cb_tc_offset_div2 and a sixth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the slice header is slice_cr_tc_offset_div2;

wherein slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify the deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for a current slice; and

wherein slice_cr_beta_offset_div2 and slice_cr_tc_offset_div2 specify the deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for the current slice.

13. A non-transitory computer-readable storage medium storing instructions that cause a processor to:

apply, in a conversion between a video comprising multiple color components and a bitstream of the video, a deblocking filter to video blocks of the multiple color components; and

perform the conversion based on the applied deblocking filter,

wherein a deblocking filter strength for the deblocking filter of the video blocks of each of the multiple color components is determined according to a rule;

wherein the rule specifies to use a different manner for determining the deblocking filter strength for the video blocks of each of the multiple color components;

wherein the multiple color components comprise at least a Cb component and a Cr component; and wherein each of the multiple color components is associated with deblocking parameter offsets for a variable beta and a variable tC in different video unit levels which are used to determine the deblocking filter strength; and

wherein the different video unit levels comprise a picture parameter set (PPS), wherein a first syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the PPS is pps_cb_beta_offset_div2 and a first syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the PPS is pps_cr_beta_offset_div2; and a second syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the PPS is pps_cb_tc_offset_div2 and a second syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the PPS is pps_cr_tc_offset_div2.

14. The non-transitory computer-readable storage medium of claim 13 ,

wherein pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify default deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in slice headers of the slices referring to the PPS; and

wherein pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify default deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cr component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the slice headers of the slices referring to the PPS.

15. The non-transitory computer-readable storage medium of claim 13 , wherein the different video unit levels comprise a picture header, wherein a third syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the picture header is pic_cb_beta_offset_div2 and a third syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the picture header is pic_cr_beta_offset_div2; and a fourth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the picture header is pic_cb_tc_offset_div2 and a fourth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the picture header is pic_cr_tc_offset_div2;

wherein pic_cb_beta_offset_div2 and pic_cb_tc_offset_div2 specify deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for slices associated with the picture header; and

wherein pic_cr_beta_offset_div2 and pic_cr_tc_offset_div2 specify deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cr component for the slices associated with the picture header.

16. The non-transitory computer-readable storage medium of claim 13 , wherein the different video unit levels comprise a slice header, wherein a fifth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the slice header is slice_cb_beta_offset_div2 and a fifth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the slice header is slice_cr_beta_offset_div2; and a sixth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the slice header is slice_cb_tc_offset_div2 and a sixth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the slice header is slice_cr_tc_offset_div2;

wherein slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify the deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for a current slice; and

wherein slice_cr_beta_offset_div2 and slice_cr_tc_offset_div2 specify the deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for the current slice.

17. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:

applying a deblocking filter to video blocks of multiple color components of a video; and

generating the bitstream based on the applying,

wherein a deblocking filter strength for the deblocking filter of the video blocks of each of the multiple color components is determined according to a rule;

wherein the rule specifies to use a different manner for determining the deblocking filter strength for the video blocks of each of the multiple color components;

wherein the multiple color components comprise at least a Cb component and a Cr component; and wherein each of the multiple color components is associated with deblocking parameter offsets for a variable beta and a variable tC in different video unit levels which are used to determine the deblocking filter strength; and

wherein the different video unit levels comprise a picture parameter set (PPS), wherein a first syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the PPS is pps_cb_beta_offset_div2 and a first syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the PPS is pps_cr_beta_offset_div2; and a second syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the PPS is pps_cb_tc_offset_div2 and a second syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the PPS is pps_cr_tc_offset_div2.

18. The non-transitory computer-readable recording medium of claim 17 ,

wherein pps_cb_beta_offset_div2 and pps_cb_tc_offset_div2 specify default deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in slice headers of the slices referring to the PPS; and

wherein pps_cr_beta_offset_div2 and pps_cr_tc_offset_div2 specify default deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cr component for slices referring to the PPS, unless the default deblocking parameter offsets are overridden by the deblocking parameter offsets present in the slice headers of the slices referring to the PPS.

19. The non-transitory computer-readable recording medium of claim 17 , wherein the different video unit levels comprise a picture header, wherein a third syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the picture header is pic_cb_beta_offset_div2 and a third syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the picture header is pic_cr_beta_offset_div2; and a fourth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the picture header is pic_cb_tc_offset_div2 and a fourth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the picture header is pic_cr_tc_offset_div2;

wherein pic_cb_beta_offset_div2 and pic_cb_tc_offset_div2 specify deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for slices associated with the picture header;

wherein pic_cr_beta_offset_div2 and pic_cr_tc_offset_div2 specify deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cr component for the slices associated with the picture header;

wherein the different video unit levels comprise a slice header, wherein a fifth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable beta in the slice header is slice_cb_beta_offset_div2 and a fifth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable beta in the slice header is slice_cr_beta_offset_div2; and a sixth syntax element associated with the Cb component indicating the deblocking parameter offsets for the variable tC in the slice header is slice_cb_tc_offset_div2 and a sixth syntax element associated with the Cr component indicating the deblocking parameter offsets for the variable tC in the slice header is slice_cr_tc_offset_div2;

wherein slice_cb_beta_offset_div2 and slice_cb_tc_offset_div2 specify the deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for a current slice; and

wherein slice_cr_beta_offset_div2 and slice_cr_tc_offset_div2 specify the deblocking parameter offsets for the variable beta and the variable tC (divided by 2) that are applied to the Cb component for the current slice.