Research In Fast Mode Decision Algorithm For Intra Prediction In H.264 Video Coding

The H.264 is a video coding standard developed by Joint Video Team (JVT) formed by ITU-T VCEG and ISO/IEC MPEG. In H.264 intra prediction coding, the time-consuming rate distortion optimization (RDO) technique with fully examing all intra prediction modes is used to select the best coding mode for each intra macroblock (MB). Therefore, the computational load of the RDO technique is extremely high.In this paper, a novel fast mode decision algorithm for H.264 intra prediction coding based on direction variation strengths (DVS) is proposed. Being different from previous methods, the block type of the MB is determined directly by comparing the DVS values of the MB with the thresholds. Furthermore, the DVS-based block edge detection is also presented to reduce the candidate modes in RDO examination. The results from experiments show that comparing to the full search algorithm used in the reference software, the proposed algorithm can reduce the time in intra prediction coding dramatically by about 70%, with the average loss in Peak-Signal-Noise-Ratio(PSNR) less than 0.2dB, and the average bit rate (BR) increase less than 3%. Comparing to Pan algorithm, Wang algorithm and Tsai algorithm, the proposed algorithm can reduce the time in intra prediction coding by nearly 10%.