Representative motion information for temporal motion prediction in video encoding and decoding

A decoder comprising:

• a memory;
• and
• one or more processors, the one or more processors being configured to decode video information at least by:
• receiving at least a portion of a compressed video bitstream;
• after decoding a reference frame, buffering in the memory representative motion-vector information and representative reference-frame index information for a group of blocks in the reference frame, the representative reference-frame index information comprising reference-frame index information of a representative block of the group of blocks in the reference frame;
• and
• decoding a current frame using the representative reference-frame index information, the representative reference-frame index information comprising the only reference-frame index information for the group of blocks in the reference frame that is buffered in the memory during the decoding of the current frame.

A computer-implemented method of decoding a compressed video bitstream, the method comprising:

• receiving at least a portion of a compressed video bitstream;
• after decoding a reference frame, buffering, in a buffer, representative motion-vector information and representative reference-frame index information for a group of blocks in the reference frame, the representative reference-frame index information comprising reference-frame index information of a representative block of the group of blocks;
• decoding a current frame using the representative reference-frame index information as reference-frame index information for a co-located block in the reference frame that is co-located with the current block in the current frame, the co-located block in the reference frame being a different block of the group of blocks than the representative block;
• and
• storing decoded video information for the current frame.