Relative SAD-based Inter Mode Decision Algorithm for H.264/AVC Video Standard

In this paper, a new relative sum of absolute difference (RSAD) based inter mode decision algorithm is proposed for H.264/AVC video standard. The main idea is to determine the best inter mode based on RSAD cost instead of the rate-distortion cost. This approach can avoid most of the computationally intensive processes in the H.264/AVC mode decision, such as integer transform, quantization, variable length coding and pixelreconstruction. Besides, it can solve the problem of SADbased cost function for H.264/AVC mode decision in biasing to the smaller block size modes, as they are normally achieving higher prediction accuracy. It is demonstrated by experimental results that the proposed RSAD-based mode decision algorithm can reduce 60% to 68% of the H.264/AVC total encoding time with negligible degradation in the rate-distortion performance. The proposed algorithm is also combined with SKIP mode early termination algorithm for further time saving and computation reduction. The enhanced algorithm with SKIP mode early termination technique could save up to 10% of the encoding time with only a little rate-distortion degradation.