关键词: 第二代数字音视频编解码标准, 高效视频编码, 样点自适应补偿, 边缘模式补偿值, 率失真代价

Abstract: Sample Adaptive Offset (SAO) is a time-consuming part of in-loop filter in the second generation of Audio Video coding Standard (AVS2) and High Efficiency Video Coding (HEVC) standard. Aiming at the problem that existing SAO algorithms had large amounts of computation and high complexity, an improved fast rate-distortion algorithm was proposed. In this new method, the original defined table of the offset values and its binary bit string to be written into the code stream were modified by analyzing the relationship between the different offset values of each class in the edge mode and its change of the rate-distortion, so that an early termination condition was set to quickly find the best offset value for the current SAO unit without calculating the rate-distortion cost of each offset. The experimental results show that, compared with the calculation results in AVS2, the proposed algorithm reduces not only the calculation amounts but also the number of cycles by 75% to find the best offset values and the operating time of in-loop filter by 33%, which effectively lowers the complexity of the calculation in ensuring the rate-distortion of image barely changed.

Key words: the second generation of Audio Video coding Standard (AVS2), High Efficiency Video Coding (HEVC), Sample Adaptive Offset (SAO), offset values of edge mode, rate-distortion cost