基于率失真联合准则的快速帧内模式选择算法

Fast Intra-prediction Mode Decision Based on Rate-distortion Joint Criterions

H.264采用率失真优化(RDO)算法,通过计算所有预测组合模式的率失真代价来确定宏块的最优编码模式,其编码复杂度和计算量也明显增加。为了降低编码运算量提高模式选择速度,通过对帧内预测模式快速选择算法的研究,提出了一种基于码率和失真度联合准则的快速帧内模式选择算法,结合提前退出策略有效减少了候选预测模式的数量。实验结果表明:与H.264参考模型JM86相比,该算法使I帧的编码速度至少提高70%,输出码率的增加低于2%,峰值信噪比(PSNR)基本保持不变。

Rate-distortion optimization （RDO） technique is employed in H.264 video coding standard to achieve coding efficiency. However, the computational complexity is extremely high since the encoder has to encode the microblock by measuring all the possible modes＇ RD costs based on the actual rate and distortion. In order to reduce complexity associated with intra prediction mode decision, special research efforts were made on intra prediction mode decision and an efficient fast mode decisions algorithm with early termination strategy to avoid unnecessary computations was proposed based on the rate and distortion Criterions. Experimental results show that the proposed scheme is able to achieve a reduction of encoding time above 70%, with the bit rate no more than 2% increase, and the negligible peak signal-noise ratio （PSNR） loss compared with the original H.264 reference software.