Dynamic Motion Estimation for Transcoding P Frames in H.264 to MPEG-2 Transcoders

Abstract — The efficiency of H.264 video compression together with the wide use of MPEG-2 today necessitates transcoding between these two technologies. The combination of bandwidth efficient technology such as H.264 and the widely deployed MPEG-2 allows for innovative video delivery services that can exploit both these technologies. Using H.264 for video delivery and MPEG-2 for playback on the end user equipment fully leverages the benefits of these technologies. This architecture requires transcoding H.264 video delivered over networks to MPEG-2 format for playback on the end-user device. We present algorithms for transcoding H.264 to MPEG-2 and evaluate the performance of these algorithms. The performance is compared with a baseline transcoder with a full decoding stage and a full encoding stage. The proposed algorithms reduce the complexity by reducing the search space for motion estimation. The results show that the proposed algorithms reduce the motion estimation complexity by over 80 % with a negligible loss in PSNR. Index Terms — H.264 transcoding, MPEG-2 transcoding, motion estimation, complexity.