Method, apparatus, and medium for video processing

1 . A method of video processing, comprising:

constructing, during a conversion between a target block of a video and a bitstream of the video, a motion candidate list for the target block;

applying a reordering or refined process to the constructed motion candidate list according to at least one criterion, wherein the reordering or refined process is based on at least one of: a template matching cost or a block boundary discontinuity measure, and wherein whether the template matching cost or the block boundary discontinuity measure is used in the reordering or refined process is based on at least one of: a flag or coding information and decoding information; and

performing the conversion based on the reordered or refined motion candidate list.

2 . The method of claim 1 , wherein the motion candidate list comprises at least one of:

a template matching (TM) merge list after at least one of: a block-based bilateral matching refinement, a template matching refinement, or a subblock-based bilateral matching refinement,

a TM advanced motion vector prediction (AMVP) list after at least one of: the block-based bilateral matching refinement, the template matching refinement, or the subblock-based bilateral matching refinement,

a regular merge list after a decoder-side motion vector refinement (DMVR) process or a multi-pass DMVR process,

a regular AMVP list after the DMVR process or the multi-pass DMVR process,

an adaptive decoder side motion vector refinement (ADMVR) merge list after the DMVR process or the multi-pass DMVR process,

a geometric partitioning mode (GPM) merge list after a template matching refinement process,

a regular merge list,

a regular AMVP list,

a TM merge list,

a TM AMVP list,

an affine merge list,

an affine AMVP list,

an intra block copy (IBC) merge list,

an IBC AMVP list,

an ADMVR merge list,

a GPM merge list,

a triangle partition mode (TPM) list,

a merge mode with motion vector difference (MMVD) merge list,

an IBC template matching candidate list,

an intra template matching candidate list,

an IBC merge mode with block vector difference (MBVD) candidate list,

an IBC GPM candidate list,

an IBC TPM candidate list, or

a specific motion candidate list.

3 . The method of claim 1 , wherein for a block vector (BV) candidate, a set of operations are performed.

4 . The method of claim 3 , wherein a set of samples included in a reference template are available, and wherein the reference template are available means that all the reference template samples are reconstructed and within at least one of the same slice, same tile, or same IBC virtual buffer.

5 . The method of claim 3 , wherein if at least a portion of samples included in a reference template are unavailable, an operation of handling the reference template outside a current picture associated with the target block is applied, and

wherein the operation comprises at least one of:

a clipping operation is applied to the BV for locating the reference template to make all the reference template samples available, or

padding the unavailable reference template samples from their corresponding available nearest samples.

6 . The method of claim 1 , wherein the boundary discontinuity measure is determined as:

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wherein P represents a prediction of the target block, R represents a reconstructed sample in a neighbor block, W represents a width of the target block, and H represents a height of the target bloc, w represents a weight factor, and x and y present variants.

7 . The method of claim 6 , wherein w1 is 0, w3 is 0, w2 is 1 and w4 is 1.

8 . The method of claim 6 , wherein w1 is 1, w3 is 1, w2 is 1 and w4 is 1.

9 . The method of claim 1 , wherein the reordering or refined process is based on a weighted average of the block boundary discontinuity measure and the template matching cost; or

wherein the weighted average of the block boundary discontinuity measure and the template matching cost is determined as:

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wherein w dis represents a weight factor for the block boundary discontinuity measure, disCost represents the block boundary discontinuity measure, w tm represents a weight factor for the template matching cost, and tmCost represents the template matching cost.

10 . The method of claim 9 , wherein w dis and w tm are predefined, or

wherein w dis and w tm are indicated, or

wherein w dis and w tm are derived according to coding information.

11 . The method of claim 9 , wherein w dis are dependent on quantization parameter (QP).

12 . The method of claim 11 , wherein w dis for a higher QP is smaller than that of a smaller QP.

13 . The method of claim 1 , wherein if a QP is higher than a predefined threshold, the template matching cost is used.

14 . The method of claim 1 , wherein the conversion includes encoding the target block into the bitstream, or

wherein the conversion includes decoding the target block 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 acts comprising:

applying, during a conversion between a target block of a video and a bitstream of the video, a reordering or refined process to motion candidates during constructing a motion candidate list based on the motion candidates, wherein the reordering or refined process is based on at least one of: a template matching cost or a block boundary discontinuity measure, and wherein whether the template matching cost or the block boundary discontinuity measure is used in the reordering or refined process is based on at least one of: a flag or coding information and decoding information; and

performing the conversion based on the constructed motion candidate list.

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

applying, during a conversion between a target block of a video and a bitstream of the video, a reordering or refined process to motion candidates during constructing a motion candidate list based on the motion candidates, wherein the reordering or refined process is based on at least one of: a template matching cost or a block boundary discontinuity measure, and wherein whether the template matching cost or the block boundary discontinuity measure is used in the reordering or refined process is based on at least one of: a flag or coding information and decoding information; and

performing the conversion based on the constructed motion candidate list.

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

applying a reordering or refined process to motion candidates during constructing a motion candidate list for a target block of the video based on the motion candidates, wherein the reordering or refined process is based on at least one of: a template matching cost or a block boundary discontinuity measure, and wherein whether the template matching cost or the block boundary discontinuity measure is used in the reordering or refined process is based on at least one of: a flag or coding information and decoding information;

generating a bitstream of the video based on the constructed motion candidate list; and

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