High performance fractional motion estimation in h.264/avc based on one-step algorithm and 8×4 element block processing

Conventional two-step algorithm, long latency of interpolation and various motion vectors are three factors that mainly induce high computation complexity of fractional motion estimation and also prevent it from encoding high-definition video. In order to overcome these obstacles, a high performance fractional motion engine is proposed in this paper with three techniques. First, based on high correlation between motion vector of a block and its up-layer as well as relationship of integer candidates, one-step algorithm is proposed. Second, an 8×4 element block processing is adopted, which not only eliminates almost redundancies in interpolation, but also still ensures hardware reusability. Finally, a scheme of processing 4×4 and 4×8 block with free of cycles is presented, so that the number of motion vectors can be reduced up to 59%. Experimental results show that the proposed design just needs 50% of gate count and 56% of cycles when compared with previous design while nearly maintaining the coding performance.