Patent ID: 6327562
Filing Date: 2001-12-04
Classification: G10L

Abstract:
A method for encoding a digital audio signal by dual analysis according to a choice criterion of LPC ""forward"" and ""backward"" analysis respectively into a transmitted encoded signal consisting of LPC filtering parameters accompanied by analysis decision information, and into a residue encoding signal, not transmitted, said digital audio signal being subdivided into frames, a succession of blocks of a specified number of samples, the encoding of said digital audio signal being carried out on this signal through a ""forward"" LPC filtering for non-stationary zones respectively on a synthesis signal, obtained from said residue encoding signal, through a ""backward"" LPC filtering for stationary zones, wherein said choice criterion consists, on each current block of said succession of current blocks constituting a current frame:in defining the degree of stationarity of the digital audio signal according to a stationarity parameter, the value of which lies between a maximum stationarity value and a minimum stationarity value;in establishing, from said stationarity parameter, an analysis choice value, from a decision function;in applying said analysis choice value to the ""forward"" LPC filtering so as to carry out the encoding of said digital audio signal by ""forward"" LPC filtering for non-stationary zones on said digital audio signal, and by ""backward"" LPC filtering respectively for stationary zones on said synthesis signal, which makes it possible to favor the maintenance of the digital audio signal in one of the ""forward"" and ""backward"" filtering modes respectively in relation to the degree of stationarity and to limit the amount of switching from one to the other and vice versa of the filtering modes.