A novel fast inter-prediction mode decision for H.264/AVC

Video coding in wireless environment requires lower computational complexity and lower energy consumption than that used in storage oriented or network oriented application. Although H.264/AVC standard provides considerable higher compression efficiency as compared to the previous standards, its complexity is significantly increased at the same time. In a H.264/AVC encoder, the most time-consuming components are variable block sizes motion estimation and mode decision using rate-distortion optimization (RDO). In this paper, we propose a novel fast inter-prediction mode decision by exploiting high correlation between rate-distortion costs (RD cost) of macroblocks in the current inter frame and their co-located macroblocks in the previous inter frame. Using this new algorithm, we can reduce a number of inter mode candidates and skip motion estimation for these modes. In addition, our algorithm can also decrease a number of tested intra modes. Simulation results show that our approach can save 20% to 50% encoding time, with a negligible PSNR loss less than 0. 1dB and bit rate increase no more than 2% for almost all the test sequences.