Abstract: AVS video standard adopts the Rate Distortion Optimization（RDO） technique to improve the compression performance in the intra prediction.Although the RDO algorithm can achieve the highest compression efficiency and the best picture quality，it increases the computational complexity.In this paper，a simple and effective fast intra mode decision algorithm for AVS1-P2 encoder is proposed.This algorithm uses the correlation of the best modes of adjacent blocks and the directivity of luminance variations within a block to reduce the candidate modes to be tested，thus the coding time is saved.Experimental results show that the coding time of the proposed algorithm is decreased by 24%~27%，compared to the full search method in the reference software of AVS1-P2 with negligible loss of PSNR and increment of bit rate.

Key words: Advanced Audio-Video Coding/Decoding Standard（AVS）, intra-prediction, mode decision, Rate Distortion Optimization（RDO）

摘要： AVS视频标准采用率失真优化（RDO）算法来提高帧内预测的压缩性能。但是RDO算法在保证编码图像获得最佳的压缩效率和图像质量的同时给整个编码过程带来了很大的计算量。提出了一种简单有效的AVS1-P2帧内预测模式的快速选择算法。该算法利用相邻块最佳预测模式之间的相关性和块内亮度变化的方向性来缩小候选模式的范围，从而有效节省了编码总时间。实验结果证明，与AVS1-P2的标准参考软件rm52j相比，本算法在保证图像质量和比特率几乎不变的情况下，编码总时间减少了24%~27%。

关键词: 数字音视频编解码技术标准, 帧内预测, 模式选择, 率失真优化