H.264帧内预测模式的快速选择算法

为了降低H.264标准中帧内预测模式选择的复杂度,提出一种快速的帧内预测方法.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,其计算复杂度非常大.提出的帧内预测快速选择方法利用宏块的绝对误差和(SAD)来缩小预测模式的范围,减少帧内预测的计算量,从而提高模式判别的速度.实验结果表明,在图像质量和码率基本保持不变的情况下,该算法使Ⅰ帧的编码速度提高约76%.

Fast selection algorithm for H.264 intra-prediction mode

To reduce computational complexity ofintra prediction in H. 264, an efficient fast mode selection is proposed. 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. The proposed fast selection algorithm for intra prediction uses stun of absolute difference (SAD) to filter out some less probable modes, reducing the complexity ofintra prediction and improving the speed of the mode decision. Experimental results show that the proposed algorithm is able to achieve a reduction of encoding time about 76% for I-frame while keeping PSNR and bite-rate almost unchanged.