Definition of zero unit
Devices, systems and methods for using zero-units in video and image coding are described. In a representative aspect, a method for processing video, including: determining, for a conversion between a block of the video and a bitstream of the video, that the block is a zero-unit (ZU) block based on one or more dimensions of the block being a non-power-of-two number, wherein no transform and inverse-transform operations are performed on the block; and performing the conversion based on the determination.
1 . A method for processing video, comprising:
determining, for a conversion between a block of the video and a bitstream of the video, that the block is a zero-unit (ZU) block based on one or more dimensions of the block being a non-power-of-two number, wherein no transform and inverse-transform operations are performed on the block;
performing the conversion based on the determining,
wherein the ZU block is a coding unit (CU) split in an asymmetric binary-tree (ABT) partitioning.
2 . The method of claim 1 , wherein, in response to determining that the block is a ZU block, setting all residuals of the ZU block to zero.
3 . The method of claim 1 , wherein any one of the dimensions of the block is an even number of a form 2 N.
4 . The method of claim 1 , wherein any one of the dimensions of the block is of a form 2 KN where K is an integer.
5 . The method of claim 1 , wherein a transform operation or an inverse-transform operation is not performed on the ZU block.
6 . The method of claim 1 , further comprising signaling an encoded ZU block in the bitstream, wherein the signaling excludes any syntax element indicating a prediction mode.
7 . The method of claim 1 , wherein motion information of the ZU block is inherited from motion information of a neighboring block.
8 . The method of claim 1 , wherein signaling does not include a cbf_flag and a cbf flag of the ZU block is inferred to be zero.
9 . The method of claim 6 , wherein the signaling excludes a transform skip flag.
10 . The method of claim 1 , wherein the ZU block is a block at a border of a picture, slice or tile.
11 . The method of claim 1 , wherein each coding unit at a border of a picture, slice, or tile is a ZU block.
12 . The method of claim 1 , wherein the ZU block may only be an inter-coded block.
13 . The method of claim 1 , wherein the determining further includes determining that the block is the ZU block due to a total number of samples of the block being greater than or equal to a threshold number T.
14 . The method of claim 1 , wherein the determining further includes determining that the block is the ZU block due to the dimensions further being greater than a first threshold for width or a second threshold for height of the block of the video.
15 . The method of claim 1 , wherein the conversion includes decoding the block from the bitstream.
16 . The method of claim 1 , wherein the conversion includes encoding the block into the bitstream.
17 . An apparatus for processing video comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:
determine, for a conversion between a block of a video and a bitstream of the video, that the block is a zero-unit (ZU) block based on one or more dimensions of the block being a non-power-of-two number, wherein no transform and inverse-transform operations are performed on the block;
perform the conversion based on the determination,
wherein the ZU block is a coding unit (CU) split in an asymmetric binary-tree (ABT) partitioning.
18 . A non-transitory computer-readable storage medium storing instructions that cause a processor to:
determine, for a conversion between a block of video and a bitstream of the video, that the block is a zero-unit (ZU) block based on one or more dimensions of the block being a non-power-of-two number, wherein no transform and inverse-transform operations are performed on the block;
perform the conversion based on the determination,
wherein the ZU block is a coding unit (CU) split in an asymmetric binary-tree (ABT) partitioning.
19 . 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:
determining, for a block of the video, that the block is a zero-unit (ZU) block based on one or more dimensions of the block being a non-power-of-two number, wherein no transform and inverse-transform operations are performed on the block;
generating the bitstream from the block based on the determining,
wherein the ZU block is a coding unit (CU) split in an asymmetric binary-tree (ABT) partitioning.