A transcoder

摘要

A transcoder for the conversion of video signals between a first and a second coding scheme employing motion compensation comprises a decoder (28) for decoding a received data stream encoded according to a first coding scheme and an encoder (30) for encoding a data stream from the decoder into a data stream according to a second coding scheme. The decoder (28) extracts motion vectors from the received data stream and passes them (42) to the data stream of the encoder, so avoiding the recalculation of the motion vectors. Drift compensation means (52-64; 70-78) may be provided to compensate for any resulting drift after a picture frame.