Fast transcoding algorithm from Mpeg2 to JVT/AVC/H.264

This paper provides an efficient method on block mode decision in transcoding from Mpeg2 to JVT/AVC/H.264. The proposed scheme makes full use of the information of sixteen Mpeg2 macroblocks corresponding to current H.264 macroblock and modes of neighboring H.264 macroblocks in the current frame and the corresponding macroblock in the immediately previous frame. When using other macroblocks' information to estimate current macroblock's mode, a definition of "candidate mode subset" has been put forward and the current macroblock makes its mode decision within this subset, whose size is smaller than the original size. By this means, an improvement in the encoding time can be achieved with negligible impact on subjective performance and the resulting PSNR. In addition, this paper makes further use of the definition, "dominant macroblocks" for block mode decision and therefore efficiently reduces the coding time consumed.