The Research Of Rate Control Algorithm In H.264/AVC Video Coding Standard

H.264/AVC is researched jointly by ITU-T Video Codec Expert Group(VCEG) and ISO/IEC Motion Picture Experts Group(MPEG) to adapted the low bit rate transmission as a new generation of international video coding standards. It has achieved significant improvements in compression performance and image quality, and a"network-friendly"representation relative to existing standards. However, Draft standards of H.264/AVC mainly focus on improving the energy efficiency of coding, but the aspect of bit-rate control is not good. Therefore, it is necessary to study deeply in bit-rate control of H.264/AVC and put forward practical solutions.The paper proposes one kind of macro-block layer rate control algorithm of H.264/AVC based on intra prediction residual. According to the data SAD(Sum of Absolute Difference) on the current macro-block coding intra prediction mode, after statistical analysis, draws experience threshold value, And it carries on comparisons between the SAD of the current macro-block and the weighted average for SADs that in the co-located position of the previous frame or adjacent to the current macro-block. If the difference between the absolute value is less than the threshold value, the quantitative parameters of the current macro-block is the weighted average for quantitative parameters that in the co-located position of the previous frame or adjacent to the current macro-block. Else, the weighted average for quantitative parameters needs to be adjusted based on SAD and the weighted average for SADs. Correspondingly for rate-distortion optimization process also take the quantitative parameters. The rate control algorithm can reach accurate rate control while keeping good and stable PSNR. Moreover the scheme output bit-rate fluctuations small and complexity low. And it is applicable to all the test sequence.