DMVR using decimated prediction block

A non-transitory machine-readable storage medium having instructions stored therein, which when executed by a processor, cause the processor to perform operations, the operations comprising:

• obtaining an initial motion vector and a reference picture for bi-prediction;
• obtaining one or more sets of candidate sample positions in the reference picture according to candidate motion vectors, wherein each candidate motion vector is derived by the initial motion vector and each preset motion vector offset, and wherein each set of candidate sample positions corresponds to each candidate motion vector;
• obtaining each set of sample positions from each set of candidate sample positions;
• computing a matching cost for each candidate motion vector within each set of sample positions;
• obtaining a refined motion vector based on the computed matching cost of each candidate motion vector;
• and
• obtaining prediction values for a current block based on the refined motion vector wherein a zipper pattern of positions of interpolated samples in a set of the candidate sample positions are chosen as the set of sample positions, wherein even parity rows produce first predicted samples at a predetermined number of contiguous sample positions that are left (or right) justified, and odd parity rows produce predicted samples at the pre-determined number of contiguous sample positions that are right (or left) justified, respectively.

A decoder, comprising:

• a processor;
• and
• a memory coupled to the processor to store instructions, executed by the processor, cause the processor to perform operations, the operations comprising:
• obtaining an initial motion vector and a reference picture for bi-prediction;
• obtaining one or more sets of candidate sample positions in the reference picture according to candidate motion vectors, wherein each candidate motion vector is derived by the initial motion vector and each preset motion vector offset, and wherein each set of candidate sample positions corresponds to each candidate motion vector;
• obtaining each set of sample positions from each set of candidate sample positions;
• computing a matching cost for each candidate motion vector within each set of sample positions;
• obtaining a refined motion vector based on the computed matching cost of each candidate motion vector;
• and
• obtaining prediction values for a current block based on the refined motion vector, wherein a zipper pattern of positions of interpolated samples in a set of the candidate sample positions are chosen as the set of sample positions, wherein even parity rows produce first predicted samples at a predetermined number of contiguous sample positions that are left (or right) justified, and odd parity rows produce predicted samples at the pre-determined number of contiguous sample positions that are right (or left) justified, respectively.