Systems and methods for decoder-side motion vector refinement subsampling

A computing system, comprising:

• control circuitry;
• memory;
• and
• one or more sets of instructions stored in the memory and configured for execution by the control circuitry, the one or more sets of instructions comprising instructions for:
• receiving video data comprising a plurality of blocks including a current block;
• identifying a current subblock in the current block;
• deriving a subsampled subblock by sub-sampling the current subblock;
• deriving, using the subsampled subblock, a set of subblock motion vectors for the current subblock;
• after applying a gradient filter to the set of subblock motion vectors, deriving a set of refined subblock motion vectors from the set of subblock motion vectors;
• and
• encoding the current subblock using the derived set of refined subblock motion vectors.

A non-transitory computer-readable storage medium storing a video bitstream that is generated by a video encoding method, the video bitstream comprising:

• an encoded current block that has been encoded using a derived set of refined subblock motion vectors;
• and
• wherein the video encoding method comprises:
• identifying a current subblock in a current block of video data;
• deriving a subsampled subblock by sub-sampling the current subblock;
• deriving, using the subsampled subblock, a set of subblock motion vectors for the current subblock;
• after applying a gradient filter to the set of subblock motion vectors, deriving a set of refined subblock motion vectors from the set of subblock motion vectors;
• and
• encoding the current subblock using the derived set of refined subblock motion vectors.