快速帧内预测模式选择新方法

为了提高编码性能,H.264采用了RDO(率失真优化),但与此同时带来的是计算复杂度的增加.本文着重分析了H.264中快速帧内预测模式选择的问题.为了降低帧内预测模式选择的计算复杂度,提出了一种高效的快速帧内预测模式选择算法.首先,对Pan的基于边缘方向直方图的快速算法进行了改进,同时提出了基于参考象素特征的4×4快速帧内预测模式选择算法,并将两者进行了结合.实验结果表明,本文算法和H.264校验模型JM61相比,I帧编码时间降低61%~69%,而PSNR基本保持不变,输出码率仅略有增加;与Pan的基于边缘方向直方图快速算法相比,本文算法的I帧编码时间降低12%~33%,PSNR和输出码率均基本保持不变.

New Fast Mode Selection for Intra Prediction

In order to maximize the coding efficiency,H.264 adopts RDO(rate distortion optimization) at the cost of a very high computational complexity.A special research effort is made on fast intra prediction mode selection in this paper.To reduce complexity associated with intra prediction mode selection,an efficient fast mode selection for intra prediction is proposed.First,the Pan's fast algorithm based on edge direction histogram is improved.Second,a 4×4 intra prediction mode selection algorithm based on the feature of the reference pixels is proposed,and then joined together with the improved Pan's algorithm.Experimental results show that,compared with the H.264 encoder JM61,the proposed scheme reduces coding time by 61%~66% for I-frame while maintaining the PSNR unchanged and increasing bit rate slightly.Furthermore,compared with Pan's scheme based on edged direction histogram,the proposed scheme reduces coding time 12%~33% for I-frame while keeping PSNR and bit rate almost unchanged.