Video compression by mean-corrected motion compensation of partial quadtrees

This paper describes Iterated Systems' submission to the MPEG-4 committee in January 1996. A system for compressing video is presented which expresses predictive frames of a sequence by means of motion vectors applied to variable-size blocks with a constant intensity adjustment. The motion vectors are organized into a partial quadtree, which allows incomplete splitting of blocks into zero to four quadrants. The motion vectors, mean intensity offsets, and partial quadtree structure are arrived at by a joint optimization process which may be carried out in a bottom-up fashion. A form of generalized overlapped block motion compensation applicable at all block sizes is presented, and a method for encoding segmented video is shown. The performance of the algorithm is compared with that of Telenor's H.263 for three of the MPEG-4 test sequences which show that the former is comparable or superior to the latter for low bit rates.