Definition of zero unit

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 at least one dimension being a non-power-of-two number, wherein no transform or inverse-transform operations are performed on the ZU block; and

performing the conversion based on the determining,

wherein, in response to the block being the ZU block, all residuals of the block are set to zero;

wherein signaling for an encoded ZU block in the bitstream excludes any syntax element indicating a prediction mode;

wherein the signaling for the encoded ZU block does not include a cbf_flag and the cbf_flag of the ZU block is inferred to be zero, or

the signaling for the encoded ZU block excludes a transform skip flag; and

wherein motion information of the ZU block is inherited from motion information of a neighboring block.

2. The method of claim 1 , wherein any one of the dimensions of the block is an even number of form 2N, where N is an integer.

3. The method of claim 1 , wherein any one of the dimensions of the block is of form 2K N where K is an integer.

4. The method of claim 1 , wherein a transform operation or an inverse-transform operation is not performed on the ZU block.

5. The method of claim 1 , wherein the ZU block is a coding unit (CU) split in an asymmetric binary-tree (ABT) partitioning.

6. The method of claim 1 , wherein the ZU block is a block at a border of a picture, slice or tile.

7. The method of claim 1 , wherein each coding unit at a border of a picture, slice, or tile is a ZU block.

8. The method of claim 1 , wherein the ZU block may only be an inter-coded block.

9. 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.

10. 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.

11. The method of claim 1 , wherein the conversion includes decoding the block from the bitstream.

12. The method of claim 1 , wherein the conversion includes encoding the block into the bitstream.

13. 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 at least one dimension being a non-power-of-two number, wherein no transform or inverse-transform operations are performed on the ZU block; and

perform the conversion based on the determination,

wherein, in response to the block being the ZU block, all residuals of the block are set to zero;

wherein signaling for an encoded ZU block in the bitstream excludes any syntax element indicating a prediction mode; and

wherein the signaling for the encoded ZU block does not include a cbf_flag and the cbf_flag of the ZU block is inferred to be zero, or

the signaling for the encoded ZU block excludes a transform skip flag; and

wherein motion information of the ZU block is inherited from motion information of a neighboring block.

14. The apparatus of claim 13 , wherein any one of the dimensions of the block is an even number of form 2N, where N is an integer.

15. 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 at least one dimension being a non-power-of-two number, wherein no transform or inverse-transform operations are performed on the ZU block; and

perform the conversion based on the determination,

wherein, in response to the block being the ZU block, all residuals of the block are set to zero;

wherein signaling for an encoded ZU block in the bitstream excludes any syntax element indicating a prediction mode; and

wherein the signaling for the encoded ZU block does not include a cbf_flag and the cbf_flag of the ZU block is inferred to be zero, or

wherein the signaling for the encoded ZU block excludes a transform skip flag; and

wherein motion information of the ZU block is inherited from motion information of a neighboring block.

16. The apparatus of claim 13 , wherein any one of the dimensions of the block is of form 2K N where K is an integer.

17. The apparatus of claim 13 , wherein a transform operation or an inverse-transform operation is not performed on the ZU block.

18. The non-transitory computer-readable storage medium of claim 15 , wherein any one of the dimensions of the block is an even number of form 2N, where N is an integer.

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 conversion between a block of the video and the bitstream, that the block is a zero-unit (ZU) block based on at least one dimension being a non-power-of-two number, wherein no transform or inverse-transform operations are performed on the ZU block; and

generating the bitstream from the block based on the determining,

wherein, in response to the block being the ZU block, all residuals of the block are set to zero;

wherein signaling for an encoded ZU block in the bitstream excludes any syntax element indicating a prediction mode; and

wherein the signaling for the encoded ZU block does not include a cbf_flag and the cbf_flag of the ZU block is inferred to be zero, or

wherein the signaling for the encoded ZU block excludes a transform skip flag; and

wherein motion information of the ZU block is inherited from motion information of a neighboring block.