Method, apparatus, and medium for video processing

1 . A method for video processing, comprising:

determining, for a conversion between a current video block of a video and a bitstream of the video, a first candidate list of the current video block based on a maximum number of motion candidates in the first candidate list;

determining a first motion candidate list of the current video block based on the first candidate list, the first motion candidate list corresponding to a first coding mode; and

performing the conversion based on the first motion candidate list,

wherein the determination of the first motion candidate list is different from a determination of a second motion candidate list of the current video block corresponding to a second coding mode.

2 . The method of claim 1 , wherein candidates in the first candidate list are unique.

3 . The method of claim 1 , wherein candidates in the first candidate list are fully pruned.

4 . The method of claim 1 , further comprising:

reordering candidates in the first candidate list.

5 . The method of claim 4 , wherein determining the first motion candidate list comprises:

adding a first number of candidates in the first candidate list into the first motion candidate list based on ordering of the first candidate list,

wherein the first number is 6.

6 . The method of claim 5 , wherein an order of the first number of candidates is kept while the first number of candidates being added into the first motion candidate list.

7 . The method of claim 1 , wherein the first motion candidate list comprises one of:

an intra block copy (IBC) merge candidate list,

an IBC advanced motion vector prediction (AMVP) candidate list,

a regular merge candidate list,

an AMVP candidate list, or

an affine merge candidate list.

8 . The method of claim 1 , further comprising:

determining at least one maximum number of candidates of at least one candidate type in the first candidate list of the current video block.

9 . The method of claim 8 , wherein the at least one maximum number comprises one of:

a first maximum number of history-based motion vector prediction (HMVP) candidates, or

a HMVP table size,

wherein the first maximum number or the HMVP table size is 25.

10 . The method of claim 1 , further comprising:

determining an intra block copy (IBC) advanced motion vector prediction (AMVP) candidate list of the current video block without reordering candidates in the IBC AMVP candidate list.

11 . The method of claim 10 , wherein determining the IBC AMVP candidate list comprises:

determining an IBC merge candidate list of the current video block; and

determining the IBC AMVP candidate list based on the IBC merge candidate list without reordering candidates in the IBC merge candidate list.

12 . The method of claim 1 , wherein a first motion vector (MV) difference threshold for the first motion candidate list is different from a second MV difference threshold for the second motion candidate list.

13 . The method of claim 1 , wherein a first motion vector (MV) difference threshold for a first motion candidate type is different from a second MV difference threshold for a second motion candidate type.

14 . The method of claim 1 , wherein a first motion vector (MV) difference threshold for a first block size is different from a second MV difference threshold for a second block size.

15 . The method of claim 1 , wherein a first motion vector (MV) difference threshold for a first MV with first fractional bits is different from a second MV difference threshold for a second MV with second fractional bits.

16 . The method of claim 1 , wherein the conversion includes encoding the current video block into the bitstream, or

wherein the conversion includes decoding the current video block from the bitstream.

17 . 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 method comprising:

determining, for a conversion between a current video block of a video and a bitstream of the video, a first candidate list of the current video block based on a maximum number of motion candidates in the first candidate list;

determining a first motion candidate list of the current video block based on the first candidate list, the first motion candidate list corresponding to a first coding mode; and

performing the conversion based on the first motion candidate list,

wherein the determination of the first motion candidate list is different from a determination of a second motion candidate list of the current video block corresponding to a second coding mode.

18 . A non-transitory computer-readable storage medium storing instructions that cause a processor to perform a method comprising:

determining, for a conversion between a current video block of a video and a bitstream of the video, a first candidate list of the current video block based on a maximum number of motion candidates in the first candidate list;

determining a first motion candidate list of the current video block based on the first candidate list, the first motion candidate list corresponding to a first coding mode; and

performing the conversion based on the first motion candidate list,

wherein the determination of the first motion candidate list is different from a determination of a second motion candidate list of the current video block corresponding to a second coding mode.

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

determining a first candidate list of a current video block of the video based on a maximum number of motion candidates in the first candidate list;

determining a first motion candidate list of the current video block based on the first candidate list, the first motion candidate list corresponding to a first coding mode;

generating the bitstream based on the first motion candidate list; and

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

wherein the determination of the first motion candidate list is different from a determination of a second motion candidate list of the current video block corresponding to a second coding mode.