INVERSIBLE METHOD OF COMPLEX FREQUENCY DECOMPOSITION OF A DIGITAL SIGNAL AND ITS APPLICATION TO A DEVICE FOR REDUCING THE INFORMATION FLOW OF AUDIONUMERIC SIGNALS

摘要

A reversible method for the complex frequency decomposition of a digital signal (Se), comprising a step of breaking the signal down into M output subbands (10) and a step of reconstituting the subbands (16), said decomposition being performed using a transform based on a "prototype" filter and a unitary transformation. The filter size is a multiple of the transformation, and the transformation is selected so that once a predetermined orthonormal basis has been defined, it has a non-empty set of columns arrangeable in pairs such that each of the points in dimension 2, where the co-ordinates are the coefficients of one line of each of the paired columns, belongs to a circle having a predetermined radius. The method is particularly useful in a device for reducing the data flow of digital audio signals (Se).