MPEG-4到H.264转码中多帧参考运动估计快速算法

针对将其他格式视频转码为H.264的过程中运动估计耗费大量时间的问题，提出了一种快速运动估计算法，以实现快速转码.该算法充分利用未转码压缩视频流中包含的信息，结合时间相关预测与空间相关预测来实现MPEG-4到H.264转码过程中的多帧参考运动估计快速算法；在此基础上提出一种自适应搜索范围选择算法，以进一步减少运动估计的计算量.该算法同样适用于其他编码标准到H.264的转码.实验结果表明，该算法在图像质量和比特率方面的表现相比参考快速算法略为逊色，但转码速度有了很大的提高.

Fast multi-frame based motion estimation algorithm for MPEG-4 to H.264 video transcoder

As the least video coding standard,H.264 has the highest coding efficiency.It's valuable to fast transcode other format video into H.264.However,motion estimation is the bottleneck in transcoding,which consumes most of the computational resource.A novel fast multi-frame based motion estimation algorithm for MPEG-4 to H.264 transcoder was proposed.Both temporal and spatial prediction methods were employed to form a high accuracy prediction scheme.An adaptive search range selection algorithm was also proposed to further speed up the processing.The proposed fast motion estimation algorithm can also be used for transcoding other format videos into H.264.Experimental results showed that,compared to reference implementation,the proposed algorithm achieves a significant improvement on transcoding speed,while PSNR decreasing and bit-rate increasing are negligible.