A frame-based MPEG characteristics extraction tool and its application in video transcoding

We present a frame-based characteristics extraction tool, which can retrieve meaningful information from MPEG-compressed bitstreams. Taking advantage of the extracted information, we present a general architecture for MPEG video transcoding, which can transcode a given MPEG video bitstream into various MPEG video bitstreams with different characteristics. We also implement an MPEG-2-to-MPEG-4 video transcoder which can not only change the bitstreams' syntax and bitrate but can also encode each semantic video segment as a group of pictures (GOPs), by using the techniques of frame type conversion and video shot boundary detection. Moreover, the proposed transcoder can intelligently select a motion mode for each macroblock of B-VOPs in an MPEG-4 video to avoid some unpredictable artifacts due to mis-selection of the motion mode. This representative application demonstrates the potential usage of such frame-based characteristics.