Patent ID: 6625320
Filing Date: 2003-09-23
Classification: H04N

Abstract:
A transcoder comprising:a decoder for decoding a received video signal coded according to a first coding scheme employing motion-compensated inter-frame predictive coding in which frames are coded out of sequence such that the coding of some frames involves prediction from a later frame using backward motion vectors, an encoder for reencoding the signal according to a second coding scheme in which at least some frames are coded using motion-compensated inter-frame predictive coding based on a reference frame which is not the same in the second coding scheme as it is in the first coding scheme, and a motion vector processor generating an estimated motion vector for a current frame of the video signal, the motion vector processor being connected to receive, when processing vectors for a current frame, vectors which, in the received signal, accompany at least one other frame of the video signal, and being operable to reverse the sign of backward motion vectors when generating estimated motion vector for use by the encoder when re-encoding using forward prediction.