System for predictive encoding/decoding of a digital speech signal by an adaptive transform with embedded codes

摘要

The invention relates to a system for the predictive encoding of a digital speech signal with embedded codes. The encoded digital signal (Sn) is formed by an encoded speech signal and, if appropriate, by auxiliary data. A perceptual weighting filter (11) is formed by a filter for short-term prediction of the speech signal to be encoded so as to produce a frequency distribution of the quantisation noise. A circuit (12) makes it possible to subtract from the perceptual signal @, the contribution from the past excitation signal @ so as to deliver an updated perceptual signal Pn. A long-term prediction circuit (13) is formed, as a closed loop, from a dictionary updated with the past excitation @ modeled for the lowest throughput and enables an optimal wave form and an associated estimated gain @ to be delivered. An orthonormal transform module (MT) includes an adaptive transform module (14) and a module (16) for progressive modelling by orthogonal vectors, this making it possible to deliver indices representing the encoded speech signal. A circuit (19) allows the insertion of auxiliary data through bit stealing from the encoded speech signal. Application to any transmission system and to the storage of speech signals. IMAGE