Fast Transcoding from H.264 AVC to High Efficiency Video Coding

In this paper, we present several strategies for transcoding from H.264/AVC bit streams to High Efficiency Video Coding (HEVC) bit streams. Because HEVC and AVC share the similar coding architecture, we try to exploit the information in AVC bit streams as much as possible. For inter picture, we utilize the power spectrum based rate-distortion optimization (PS-RDO) model as well as the input residual, modes and motion vectors to estimate the best coding unit (CU) split quad tree, the best prediction unit (PU) mode and the best motion vector of each PU partition For intra picture, we propose to reduce the CU and PU partition candidates. The proposed strategies can significantly reduce the transcoding complexity in terms of reduced processing for RDO evaluations, motion estimation, motion compensation as well as fractional pixel interpolation operations. Experiment results show that the proposed transcoding methods can achieve a good tradeoff between coding efficiency and transcoding complexity.