Patent ID: 6999512

Claim:
A transcoding method of performing conversion between compressed bitstreams having at least syntax elements and video elements corresponding to video data, the transcoding method comprising the steps of: a) decoding a first bitstream compressed according to a first compression method and parsing syntax elements and video elements; b) mapping the parsed syntax elements to syntax elements complying with a target second compression method; c) partially reconstructing video data complying with the first compression method from the parsed video elements; d) requantizing the video data reconstructed in the step c) according to the second compression method; and e) coding the mapped syntax elements and the requantized video data to obtain a bitstream complying with the second compression method, wherein the first compression method is a moving picture experts group (MPEG)-1 compression method, the second compression method is an MPEG-4 compression method, and the step b) comprises: b-1) converting an MPEG-1 f_code into an MPEG-4 f_code; b-2) converting an MPEG-1 macroblock (MB) type into an MPEG-4 MB type; b-3) converting an MPEG-1 coded block pattern (CBP) into an MPEG-4 CBP; and b-4) converting an MPEG-1 MQUANT value into an MPEG-4 DQUANT value corresponding to a difference of quantization parameters.