Decoder side MV derivation and refinement

An apparatus, comprising:

• processing circuitry configured to:
• receive a first motion vector and a second motion vector for a first block in a current picture of a video, the first motion vector being indicative of a first reference block in a first picture, and the second motion vector being indicative of a second reference block in a second picture;
• generate a bilateral template based on a weighted combination of the first reference block and the second reference block:
• determine a refined first motion vector based on the bilateral template and a first set of reference blocks in the first picture;
• determine a refined second motion vector based on the bilateral template and a second set of reference blocks in the second picture;
• reconstruct, by application of a final motion compensation interpolation filter, the first block according to (i) the refined first motion vector and (ii) the refined second motion vector,
• wherein, prior to reconstructing the first block, the processing circuitry is configured to determine an initial motion vector of a second block that is coded after the first block according to at least one of the first motion vector and the second motion vector for the first block, and
• the final motion compensation interpolation filter has a filter length based on a search range used to determine the first set of reference blocks or the second set of reference blocks.

A non-transitory computer-readable storage medium storing instructions, which, when executed by a computer for video decoding, cause the computer to perform a method comprising:

• receiving a first motion vector and a second motion vector for a first block in a current picture of a video, the first motion vector being indicative of a first reference block in a first picture, and the second motion vector being indicative of a second reference block in a second picture:
• generating a bilateral template based on a weighted combination of the first reference block and the second reference block:
• determining a refined first motion vector based on the bilateral template and a first set of reference blocks in the first picture;
• determining a refined second motion vector based on the bilateral template and a second set of reference blocks in the second picture;
• and
• reconstructing, by applying a final motion compensation interpolation filter, the first block according to (i) the refined first motion vector, and (ii) the refined second motion vector,
• wherein, prior to the reconstructing, the method comprises determining an initial motion vector of a second block that is coded after the first block according to at least one of the first motion vector and the second motion vector for the first block, and
• the final motion compensation interpolation filter has a filter length based on a search range used to determine the first set of reference blocks or the second set of reference blocks.