US Patent 7269304 Transcoder system for adaptively reducing frame-rate

A transcoder system for adaptively reducing frame rate is provided, which can change audio-visual stream of a GOP (group of picture). Each picture in the GOP consists of a plurality of macroblocks. The transcoder system includes a switching device, a variable length decoder, a motion vector compensation device, a memory and an encoder/decoder. The motion vector compensation device can compute output motion vectors respectively for the macroblocks in accordance with input picture types, so video data of I-, P- and B-pictures without complete reduced frame-rate transcoding in the prior art can be avoided. Therefore, video transcoding for pictures can be performed completely and quickly to thus reduce required transcoding computation and further increase transcoding speed.