Patent ID: 8078457

Claim:
A method performed by a coder for coding a digital speech signal according to a second format of coding, from information corresponding to a first format of coding, comprising: carrying out at least one coding step according to the first format of coding; interpolating a value representative of a first plurality of linear predictive coding (LPC) coefficients corresponding to the first format, between a given block and a preceding block, which precedes the given block, to provide a second plurality of LPC coefficients corresponding to the second format, wherein the first and second formats use, LPC short-term prediction models on digital speech signal sample blocks, by using filters represented by the respective first and second pluralities of LPC coefficients, wherein the method further comprises: a step of detection of a break in stationarity of the digital speech signal at least between the given block and the preceding block, a step of interpolation performed dynamically, by choosing for each current block at least one interpolation factor from a preselection of factors, according to said detection, and a step of transforming said digital speech signal into a coded signal according to said second format of coding, using said LPC coefficients of the second format obtained by said interpolation, and wherein: a moment of break in stationarity is detected between a given block and a preceding block this break moment is compared with a time position of a current block in the second format, and, in the interpolation, more weight is assigned to the LPC coefficients of the first format that are associated with the given block if the block of the second format occurs after the detected break moment, or to the LPC coefficients of the first format that are associated with the preceding block if the block of the second format occurs before the detected break moment.