Patent ID: 9734834
Date: 2017-08-15
CPC Classifications: G10L,H04M

Claim:
1. A system, including a processor in communication with a memory, for generating comfort noise for a stream of frames carrying an audio signal, the system comprising: frame characterising logic configured to generate a set of filter parameters characterising the frequency content of a frame; an analysis filter adapted using the filter parameters and configured to filter the frame so as to generate residual samples, said analysis filter being an inverse LPC filter; an analysis controller configured to receive an indication that the frame does not comprise speech and, responsive to the indication, cause the residual samples to be stored in a store; and a synthesis controller operable to select, from the store, stored residual samples which have been generated by the analysis filter and cause a synthesis filter, inverse to the analysis filter and adapted using filter parameters generated at the frame characterising logic for one or more frames not comprising speech, to filter the selected residual samples so as to generate a frame of comfort noise, said synthesis filter being an LPC filter, and said synthesis controller being configured to select stored residual samples at random from the store sufficient to generate the frame of comfort noise.