Patent ID: 7012960

Claim:
A method of transcoding a primary encoded signal (S 1 ) comprising a sequence of pictures, into a secondary encoded signal (S 2 ), said method of transcoding comprising at least the steps of: decoding a current picture of the primary encoded signal, said decoding step comprising a dequantizing sub-step ( 12 ) for producing a first transformed signal (R 1 ), encoding, following the decoding step, for obtaining the secondary encoded signal, said encoding step comprising a quantizing sub-step ( 13 ), wherein said method of transcoding further comprises a filtering step between the dequantizing sub-step and the quantizing sub-step, said filtering step using a recursive filter wherein the recursive filtering step is intended to use a recursive filter such as: Rf[i]=(1—.alpha.[i]) (R 1 [i]+Rmc[i]), where Rf[i], R 1 [i] and Rmc[i] are transformed coefficients comprised in the transformed signals (Rf,R 1 ,Rmc) and .alpha.[i] is a filter coefficient comprised between 0 and 1; and predicting a transformed motion-compensated signal from a transformed encoding error derived from the encoding step, said prediction step being situated between the encoding and decoding steps, wherein the recursive filtering step is for receiving the transformed motion-compensated signal and the first transformed signal and for delivering a filtered transformed signal to the quantizing sub-step.