Fast multiframe selection algorithm based on spatial-temporal characteristics of motion field

H.264 adopts multiple reference frames for motion estimation. This now feature significantly improves the prediction accuracy of intercoding blocks, but it results in a considerable increase in encoder complexity. The reference software JM adopts the full search scheme of which the increased computation is in proportion to the number of searched reference frames. However the reduction of prediction residues is highly dependent on the nature of sequences, not on the number of searched frames. We propose a fast multiframe selection algorithm to deduct unnecessary reference frame searches, where the nearest reference frame (ref(0)) is first searched, and the motion vectors from ref(0) compose motion field distribution. Based on the spatial and temporal consistencies of the motion field, only a small number of MBs select multiframe motion estimation. Simulation results show that the proposed algorithm can reduce more than 50% motion estimation computation cost on average and still maintain similar coding efficiency. (C) 2008 SPIE and IS&T [DOI: 10.1117/1.2991409]