Update of look-up tables

1. A method for video processing, comprising:

constructing a motion candidate list for a current block of a video;

deriving motion information for the current block based on the motion candidate list; and

performing a conversion between the current block and a bitstream of the video based on the motion information of the current block, wherein whether to update a table of motion candidates using the motion information of the current block is based on a coding characteristic of the current block; and

constructing, based on the table, a motion candidate list for a subsequence block to derive motion information of a subsequence block,

wherein the coding characteristic is related to whether the current block is a last block in a plurality of blocks related to a region.

2. The method of claim 1 , wherein the performing a conversion comprises:

encoding the current block into the bitstream.

3. The method of claim 1 , wherein the performing a conversion comprises:

decoding the current block from the bitstream.

4. The method of claim 1 , wherein the coding characteristic comprises a coding mode of the current block.

5. The method of claim 4 , wherein the table is updated based on the coding mode of the current block belonging to at least one first coding mode.

6. The method of claim 5 , wherein the at least one first coding mode comprises at least one of:

a merge mode which is a non-affine merge mode, an Advanced Motion Vector Prediction (AMVP) mode which is a non-affine AMVP mode, or an inter mode.

7. The method of claim 1 , wherein the table is not updated based on the coding mode belonging to at least one second coding mode.

8. The method of claim 7 , wherein the at least one second coding mode comprises at least one of:

an intra mode, an affine mode, an affine AMVP mode, or an affine merge mode.

9. The method of claim 1 , wherein the coding characteristic is related to whether the current block is the last block in the plurality of blocks in the region.

10. The method of claim 1 , wherein the motion information of the current block is used to update the table based on the current block being a last block in a plurality of blocks in a region.

11. The method of claim 10 , wherein updating of the table with motion information of other blocks in the plurality of blocks is refrained from.

12. The method of claim 1 , wherein there is a possibility not to update the table using the motion information of the current block if the table is used during constructing the candidate list.

13. The method of claim 1 , wherein there is a possibility to update the table using the motion information of the current block if the table is not used during constructing the candidate list.

14. The method of claim 1 , wherein the table is update using motion information associated with a plurality of blocks in a given region.

15. The method of claim 1 , wherein a motion candidate in the table is associated with motion information including at least one of: a prediction direction, a reference picture index, motion vector values, an intensity compensation flag, an affine flag, a motion vector difference precision, a filter parameter used in a filtering process, or a motion vector difference value.

16. A method for video processing, comprising:

constructing a motion candidate list for a current block of a video;

deriving motion information for the current block based on the motion candidate list; and

performing a conversion between the current block and a bitstream of the video based on the motion information of the current block, wherein whether to update a table of motion candidates using the motion information of the current block is based on a coding characteristic of the current block; and

constructing, based on the table, a motion candidate list for a subsequence block to derive motion information of a subsequence block, wherein the table is updated periodically.

17. A method for video processing, comprising:

constructing a motion candidate list for a current block of a video;

deriving motion information for the current block based on the motion candidate list; and

performing a conversion between the current block and a bitstream of the video based on the motion information of the current block, wherein whether to update a table of motion candidates using the motion information of the current block is based on a coding characteristic of the current block; and

constructing, based on the table, a motion candidate list for a subsequence block to derive motion information of a subsequence block, wherein the table is updated each time after a given region of a video frame is processed.

18. The method of claim 17 , wherein the given region comprises one of a slice, N largest coding units (LCUs), N coding units (CUs), or N inter-coded coding units (CUs), N being an integer.

19. 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:

constructing a motion candidate list for a current block of a video;

deriving motion information for the current block based on the motion candidate list; and

performing a conversion between the current block and a bitstream of the video based on the motion information of the current block, wherein whether to update a table of motion candidates using the motion information of the current block is based on a coding characteristic of the current block; and

constructing, based on the table, a motion candidate list for a subsequence block to derive motion information of a subsequence block,

wherein the coding characteristic is related with whether the current block is a last block in a plurality of blocks related to a region.

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

constructing a motion candidate list for a current block of a video;

deriving motion information for the current block based on the motion candidate list; and

performing a conversion between the current block and a bitstream of the video based on the motion information of the current block, wherein whether to update a table of motion candidates using the motion information of the current block is based on a coding characteristic of the current block; and

constructing, based on the table, a motion candidate list for a subsequence block to derive motion information of a subsequence block,

wherein the coding characteristic is related with whether the current block is a last block in a plurality of blocks related to a region.

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

constructing a motion candidate list for a current block of a video;

deriving motion information for the current block based on the motion candidate list; and

performing a conversion between the current block and a bitstream of the video based on the motion information of the current block, wherein whether to update a table of motion candidates using the motion information of the current block is based on a coding characteristic of the current block; and

constructing, based on the table, a motion candidate list for a subsequence block to derive motion information of a subsequence block,

wherein the coding characteristic is related with whether the current block is a last block in a plurality of blocks related to a region.