Novel Fast Mode Decision Algorithm for P-Slices in H.264/AVC

H.264/AVC encoder complexity is remarkable mainly due to variable block size motion estimation (ME) and exhaustive rate distortion optimization (RDO). This makes real-time video coding very difficult. In this paper, a novel fast mode decision algorithm for P-slices is presented to reduce the computational load. Based on the temporal and spatial correlation between macroblocks, a four paths prediction structure is proposed with flexible early termination strategy. Experiment results show that with this algorithm, 42%-65% encoding time can be saved with a negligible loss in peak signal-to-noise ratio (PSNR) and very little increment in bit rate. Combined with Choi´s method, our algorithm can achieve a time reduction up to 74.31% with little loss in coding efficiency.