Handling of Decoder-Side Motion Vector Refinement (DMVR) Coding Tool for Reference Picture Resampling in Video Coding

A method of encoding a video bitstream implemented by a video encoder, the method comprising:

• determining, by the video encoder, whether a resolution of a current picture being encoded is the same as a resolution of reference pictures identified in a reference picture list associated with the current picture;
• enabling, by the video encoder, decoder-side motion vector refinement (DMVR) for a current block of the current picture when the resolution of the current picture is determined to be the same as the resolution of each of the reference pictures;
• disabling, by the video encoder, the DMVR for the current block of the current picture when the resolution of the current picture is determined to be different than the resolution of either of the reference pictures;
• and
• refining, by the video encoder, motion vectors corresponding to the current block using the DMVR when the DMVR is enabled for the current block.

A decoding device, comprising:

• a receiver configured to receive a coded video bitstream;
• a memory coupled to the receiver, the memory storing instructions;
• and
• a processor coupled to the memory, the processor configured to execute the instructions to cause the decoding device to:
• determine whether a resolution of a current picture being decoded is the same as a resolution of reference pictures identified by a reference picture list associated with the current picture;
• enable decoder-side motion vector refinement (DMVR) for a current block of the current picture when the resolution of the current picture is determined to be the same as the resolution of each of the reference pictures;
• disable the DMVR for the current block of the current picture when the resolution of the current picture is determined to be different than the resolution of either of the reference pictures;
• and
• refine motion vectors corresponding to the current block using the DMVR when the DMVR is enabled for the current block.

An encoding device, comprising:

• a memory containing instructions;
• a processor coupled to the memory, the processor configured to implement the instructions to cause the encoding device to:
• determine whether a resolution of a current picture being encoded is the same as a resolution of reference pictures identified in a reference picture list associated with a current block;
• enable decoder-side motion vector refinement (DMVR) for a current block of the current picture when the resolution of the current picture is determined to be the same as the resolution of each of the reference pictures;
• disable the DMVR for the current block of the current picture when the resolution of the current picture is determined to be different than the resolution of either of the reference pictures;
• and
• refine motion vectors corresponding to the current block using the DMVR when a DMVR flag is enabled for the current block;
• and
• a transmitter coupled to the processor, the transmitter configured to transmit a video bitstream containing the current block toward a video decoder.