Low complexity video transcoding algorithm from H.264 to HEVC

A low complexity video transcoding algorithm from H.264 video to the next generation video compression standard the high efficiency video coding (HEVC) was proposed in order to reduce the computational time consumed during the transcoding process. By making full use of the H.264 compressed video information included in the bitstream, the coding complexity of each frame was analyzed based on the correlation between image complexities and coding bits, and then the searching depth range was adaptively decided based on the analysis results. By exploiting the mapping correlations of Skip mode in HEVC and all modes in H.264, an early decision of Skip mode was then introduced. Through the statistical analysis of coding bits, a fast prediction unit partition selection for both symmetric and asymmetric partitions was described. Finally, the motion estimation process was optimized according to the motion similarity between H.264 and HEVC bitstreams. Experimental results show that, compared to the reference methods, the proposed algorithm achieves a significant improvement on transcoding speed, while maintaining similar rate-distortion performance.