Abstract
H.264/AVC introduces variable-block size coding modes, which can improve coding efficiency but also increases computational complexity very much. The extreme computational complexity makes H.264/AVC hard to be realized practically. In the past, many fast mode decision algorithms were proposed to partially reduce the complexity of mode selection. However, most of them are with fixed complexity. In this study we attempt to bring out a fast mode decision algorithm for H.264/AVC adapting to different computation limits. A mode decision algorithm based on computation-aware architecture is proposed. This algorithm uses the characteristics of a priority list to make a decision on coding modes based on some profitable observations on the relationship between priority lists, corresponding to consecutive frames and their block coding modes. The simulation results show that the proposed method can scale down the H.264/AVC complexity from 1/2 to 1/64 in terms of the number of 4×4 block SADs required, while maintaining the acceptable video quality. In real implementation on H.264/AVC JM9, this program has 2 to 19 times speed-up in motion estimation time, or 1.3 to 3.5 times speed-up of the total encoding time.