A compact motion estimator with a simplified vector search strategy maintaining encoded picture quality

A compact motion estimator employing a simplified two-step full-search strategy has been proposed. In the first step, 2-pel precision motion vectors are obtained using 4-to-1 subsampling with a LPF. In the second step, half-pel precision vectors are obtained. The strategy reduces the number of operations and memory access cycles to 1/11 and 1/2, respectively, while maintaining encoded picture quality within 0.2 dB differences in SNRs. Using this estimator, a bidirectional motion compensation LSI with a -16.0/+15.5 pels search range has been developed for real-time MPEG1 video encoding.