Interplay between in-loop filtering and video tiles

1 . A method of processing video data, comprising:

performing a conversion between a video comprising a video unit and a bitstream of the video,

wherein the bitstream conforms to a format rule,

wherein the format rule specifies that information about applicability of a tool to the conversion is allowed to be indicated in the bitstream at both a video slice level and a video picture level, and the tool maps luma samples to particular values and selectively applies a scaling operation to the values of chroma samples, and

wherein whether the information about applicability of the tool to the conversion is allowed to be indicated in the bitstream at the video slice level depends on a syntax element indicating whether the tool is allowed to the conversion indicated in the video picture level.

2 . The method of claim 1 , wherein the format rule further specifies that a first syntax element indicating whether an in-loop filtering operation is allowed to be performed across tile boundaries is selectively included in the bitstream responsive to whether the video unit is partitioned into more than one tile.

3 . The method of claim 2 , wherein the video unit is a picture, and wherein the first syntax element is in a picture parameter set.

4 . The method of claim 2 , wherein the format rule specifies that the first syntax element is included in the bitstream in response to the video unit being partitioned into more than one tile, and that the first syntax element is excluded from the bitstream in response to the video unit comprising only one tile.

5 . The method of claim 2 , wherein the format rule specifies that the first syntax element is included in the bitstream in response to the bitstream including a value of zero for a second constraints information syntax element, wherein the second constraints information syntax element indicates whether there is only one tile per picture as a constraint and the zero value for the second constraints information syntax element indicates that the constraint is not imposed.

6 . The method of claim 5 , wherein the second constraints information syntax element is one_tile_per_pic_constraint_flag, and wherein the first syntax element is loop_filter_across_tiles_enabled_flag.

7 . The method of claim 2 , wherein the format rule specifies that the first syntax element is inferred to be equal to zero and is excluded from the bitstream in response to the bitstream including a value of one for a second constraints information syntax element, wherein the second constraints information syntax element indicates whether there is only one tile per picture as a constraint and the one value for the second constraints information syntax element indicates that the constraint is imposed, the zero value for the first syntax element indicates that the in-loop filtering operation across tile boundaries is disabled.

8 . The method of claim 2 , wherein the in-loop filtering operation includes at least one of a deblocking filter operation, a sample adaptive offset operation, or an adaptive loop filter operation.

9 . The method of claim 1 , wherein the format rule further specifies that a third syntax element indicating whether an in-loop filtering operation is allowed to be performed across slice boundaries is selectively included in the bitstream responsive to whether the video unit is partitioned into more than one slice.

10 . The method of claim 9 , wherein the third syntax element is in a picture parameter set.

11 . The method of claim 9 , wherein the video unit is a sub-picture, and the format rule specifies that the third syntax element is included in the bitstream in response to the sub-picture being partitioned into only one slice, and wherein the third syntax element is included in the bitstream in response to a first flag being equal to 1 which specifies that each sub-picture consists of one and only one rectangular slice, wherein the first flag is single_slice per_subpic_flag, and wherein the first flag is in a picture parameter set.

12 . The method of claim 9 , wherein the video unit is a picture, and the format rule further specifies that the third syntax element is included in the bitstream in response to the picture being partitioned in a non-rectangular shape, wherein the format rule specifies that the third syntax element is included in the bitstream in response to a second flag being equal to 0 which specifies that a raster-scan slice mode is in use for the picture, wherein the raster-scan slice mode is a non-rectangular slice mode, wherein the second flag is rect_slice_flag, and wherein the second flag is in a picture parameter set.

13 . The method of claim 1 , wherein the conversion comprises encoding the video into the bitstream.

14 . The method of claim 1 , wherein the conversion comprises decoding the video from the bitstream.

15 . 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:

perform a conversion between a video comprising a video unit and a bitstream of the video,

wherein the bitstream conforms to a format rule,

wherein the format rule specifies that information about applicability of a tool to the conversion is allowed to be indicated in the bitstream at both a video slice level and a video picture level, and the tool maps luma samples to particular values and selectively applies a scaling operation to the values of chroma samples, and

wherein whether the information about applicability of the tool to the conversion is allowed to be indicated in the bitstream at the video slice level depends on a syntax element indicating whether the tool is allowed to the conversion indicated in the video picture level.

16 . The apparatus of claim 15 , wherein the format rule further specifies that a first syntax element indicating whether an in-loop filtering operation is allowed to be performed across tile boundaries is selectively included in the bitstream responsive to whether the video unit is partitioned into more than one tile;

wherein the video unit is a picture;

wherein the format rule specifies that the first syntax element is included in the bitstream in response to the video unit being partitioned into more than one tile;

wherein the format rule specifies that the first syntax element is excluded from the bitstream in response to the video unit comprising only one tile;

wherein the in-loop filtering operation includes at least one of a deblocking filter operation, a sample adaptive offset operation, or an adaptive loop filter operation;

wherein the first syntax element is loop_filter_across_tiles_enabled_flag;

wherein the format rule specifies that the first syntax element is included in the bitstream in response to the bitstream including a value of zero for a second constraints information syntax element, wherein the second constraints information syntax element indicates whether there is only one tile per picture as a constraint and the zero value for the second constraints information syntax element indicates that the constraint is not imposed;

wherein the format rule specifies that the first syntax element is inferred to be equal to zero and is excluded from the bitstream in response to the bitstream including a value of one for a second constraints information syntax element, wherein the second constraints information syntax element indicates whether there is only one tile per picture as a constraint and the one value for the second constraints information syntax element indicates that the constraint is imposed, the zero value for the first syntax element indicates that the in-loop filtering operation across tile boundaries is disabled;

wherein the second syntax element is one_tile_per_pic_constraint_flag;

wherein the format rule further specifies that a third syntax element indicating whether an in-loop filtering operation is allowed to be performed across slice boundaries is selectively included in the bitstream responsive to whether the video unit is partitioned into more than one slice;

wherein the third syntax element is in a picture parameter set; and

wherein the video unit is a sub-picture, and the format rule specifies that the third syntax element is included in the bitstream in response to the sub-picture being partitioned into only one slice, and wherein the third syntax element is included in the bitstream in response to a first flag being equal to 1 which specifies that each sub-picture consists of one and only one rectangular slice, wherein the first flag is single_slice_per_subpic_flag, and wherein the first flag is in a picture parameter set; or wherein the video unit is a picture, and the format rule further specifies that the third syntax element is included in the bitstream in response to the picture being partitioned in a non-rectangular shape, wherein the format rule specifies that the third syntax element is included in the bitstream in response to a second flag being equal to 0 which specifies that a raster-scan slice mode is in use for the picture, wherein the raster-scan slice mode is a non-rectangular slice mode, wherein the second flag is rect_slice_flag, and wherein the second flag is in a picture parameter set.

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

perform a conversion between a video comprising a video unit and a bitstream of the video,

wherein the bitstream conforms to a format rule,

wherein the format rule specifies that information about applicability of a tool to the conversion is allowed to be indicated in the bitstream at both a video slice level and a video picture level, and the tool maps luma samples to particular values and selectively applies a scaling operation to the values of chroma samples, and

wherein whether the information about applicability of the tool to the conversion is allowed to be indicated in the bitstream at the video slice level depends on a syntax element indicating whether the tool is allowed to the conversion indicated in the video picture level.

18 . The non-transitory computer-readable storage medium of claim 17 , wherein the format rule further specifies that a first syntax element indicating whether an in-loop filtering operation is allowed to be performed across tile boundaries is selectively included in the bitstream responsive to whether the video unit is partitioned into more than one tile;

wherein the video unit is a picture;

wherein the format rule specifies that the first syntax element is included in the bitstream in response to the video unit being partitioned into more than one tile;

wherein the format rule specifies that the first syntax element is excluded from the bitstream in response to the video unit comprising only one tile;

wherein the in-loop filtering operation includes at least one of a deblocking filter operation, a sample adaptive offset operation, or an adaptive loop filter operation;

wherein the first syntax element is loop_filter_across_tiles_enabled_flag;

wherein the format rule specifies that the first syntax element is included in the bitstream in response to the bitstream including a value of zero for a second constraints information syntax element, wherein the second constraints information syntax element indicates whether there is only one tile per picture as a constraint and the zero value for the second constraints information syntax element indicates that the constraint is not imposed;

wherein the format rule specifies that the first syntax element is inferred to be equal to zero and is excluded from the bitstream in response to the bitstream including a value of one for a second constraints information syntax element, wherein the second constraints information syntax element indicates whether there is only one tile per picture as a constraint and the one value for the second constraints information syntax element indicates that the constraint is imposed, the zero value for the first syntax element indicates that the in-loop filtering operation across tile boundaries is disabled;

wherein the second syntax element is one_tile_per_pic_constraint_flag;

wherein the format rule further specifies that a third syntax element indicating whether an in-loop filtering operation is allowed to be performed across slice boundaries is selectively included in the bitstream responsive to whether the video unit is partitioned into more than one slice;

wherein the third syntax element is in a picture parameter set; and

wherein the video unit is a sub-picture, and the format rule specifies that the third syntax element is included in the bitstream in response to the sub-picture being partitioned into only one slice, and wherein the third syntax element is included in the bitstream in response to a first flag being equal to 1 which specifies that each sub-picture consists of one and only one rectangular slice, wherein the first flag is single_slice_per_subpic_flag, and wherein the first flag is in a picture parameter set; or wherein the video unit is a picture, and the format rule further specifies that the third syntax element is included in the bitstream in response to the picture being partitioned in a non-rectangular shape, wherein the format rule specifies that the third syntax element is included in the bitstream in response to a second flag being equal to 0 which specifies that a raster-scan slice mode is in use for the picture, wherein the raster-scan slice mode is a non-rectangular slice mode, wherein the second flag is rect_slice_flag, and wherein the second flag is in a picture parameter set.

19 . A method for storing a bitstream of a video, comprising:

generating a bitstream for a video comprising a video unit; and

storing the bitstream in a non-transitory computer-readable recording medium,

wherein the bitstream conforms to a format rule,

wherein the format rule specifies that information about applicability of a tool to generating the bitstream is allowed to be indicated in the bitstream at both a video slice level and a video picture level, and the tool maps luma samples to particular values and selectively applies a scaling operation to the values of chroma samples, and

wherein whether the information about applicability of the tool to the conversion is allowed to be indicated in the bitstream at the video slice level depends on a syntax element indicating whether the tool is allowed to the conversion indicated in the video picture level.

20 . The method of claim 19 , wherein the format rule further specifies that a first syntax element indicating whether an in-loop filtering operation is allowed to be performed across tile boundaries is selectively included in the bitstream responsive to whether the video unit is partitioned into more than one tile;

wherein the video unit is a picture;

wherein the format rule specifies that the first syntax element is included in the bitstream in response to the video unit being partitioned into more than one tile;

wherein the format rule specifies that the first syntax element is excluded from the bitstream in response to the video unit comprising only one tile;

wherein the in-loop filtering operation includes at least one of a deblocking filter operation, a sample adaptive offset operation, or an adaptive loop filter operation;

wherein the first syntax element is loop_filter_across_tiles_enabled_flag;

wherein the format rule specifies that the first syntax element is included in the bitstream in response to the bitstream including a value of zero for a second constraints information syntax element, wherein the second constraints information syntax element indicates whether there is only one tile per picture as a constraint and the zero value for the second constraints information syntax element indicates that the constraint is not imposed;

wherein the format rule specifies that the first syntax element is inferred to be equal to zero and is excluded from the bitstream in response to the bitstream including a value of one for a second constraints information syntax element, wherein the second constraints information syntax element indicates whether there is only one tile per picture as a constraint and the one value for the second constraints information syntax element indicates that the constraint is imposed, the zero value for the first syntax element indicates that the in-loop filtering operation across tile boundaries is disabled;

wherein the second syntax element is one_tile_per_pic_constraint_flag;

wherein the format rule further specifies that a third syntax element indicating whether an in-loop filtering operation is allowed to be performed across slice boundaries is selectively included in the bitstream responsive to whether the video unit is partitioned into more than one slice;

wherein the third syntax element is in a picture parameter set; and

wherein the video unit is a sub-picture, and the format rule specifies that the third syntax element is included in the bitstream in response to the sub-picture being partitioned into only one slice, and wherein the third syntax element is included in the bitstream in response to a first flag being equal to 1 which specifies that each sub-picture consists of one and only one rectangular slice, wherein the first flag is single_slice_per_subpic_flag, and wherein the first flag is in a picture parameter set; or wherein the video unit is a picture, and the format rule further specifies that the third syntax element is included in the bitstream in response to the picture being partitioned in a non-rectangular shape, wherein the format rule specifies that the third syntax element is included in the bitstream in response to a second flag being equal to 0 which specifies that a raster-scan slice mode is in use for the picture, wherein the raster-scan slice mode is a non-rectangular slice mode, wherein the second flag is rect_slice_flag, and wherein the second flag is in a picture parameter set.