Single-iteration full-search fractional motion estimation for quad full HD H.264/AVC encoding

Fractional motion estimation (FME) is widely used in video compression standards. In H.264/AVC, the precision of motion vector is down to quarter pixels to improve the coding efficiency. However, FME occupies over 45% of the computation complexity in an H.264 encoder and this high complexity limits the processing capability. In this paper, a single-iteration full search FME is proposed. By the algorithm and architecture co-optimization, the bandwidth to the frame buffer is reduced by 31%. Furthermore, 82% of circuit area for the Hadamard transformation and subtraction are saved from the direct implementation. Compared with prior arts, the proposed design supports 3.39 times higher throughput with only 0.02 dB PSNR drop. Thus, the specification of 4096 times 2160 quad full high definition H.264/AVC FME processing can be achieved.