A method/system of transcoding an MPEG 2/4 bit stream into an H.264 format, handles an input MPEG 2/4 bit stream in a decoder, and identifies certain data in the input bit stream for reuse in the H.264 format; and, reuses the identified data in a re-encoder with assistance from a mapping module in transcoding by converting the input bit stream into an output H.264 format. The identified data includes information at a macrolevel and information at a picture level. The information at the macrolevel might comprise additional stages incorporated in the re-encoder module including a Mapping Process stage, a Sub Pixel Refinement stage, a Mode Selection stage to choose from Intra, Inter or Skip modes, followed by the standard H.264 encoding loop and the Entropy Coding Block. The information at the picture level might include; a) average quantizer of frame, and, b) total bits per frame.