Method and system for generating colored comfort noise in the absence of silence insertion description packets

Abstract

A method and system for utilizing information content in speech and a transition hangover between speech and noise to generate comfort noise on the decoder side. This adaptation to noise may be accomplished using various algorithms of estimating the spectrum of color noise. According to an embodiment of the present invention, an adaptation algorithm may be implemented that adapts, with time, rather than a block based algorithm to prevent the repeated generation of artifacts present in the block that are being adapting to. The method and system of the present invention generates comfort noise in the absence of silent insertion descriptions containing spectrum information thereby saving bandwidth and generating colored comfort noise that reflects the spectrum of the actual noise.

1 .- 42 . (canceled)  
     
     
         43 . A method for generating comfort noise at a decoder side in the absence of silence insertion description packets containing spectrum information transmitted by an encoder side, the method comprising the steps of: 
 receiving a voice signal wherein the voice signal contains silence packets at the decoder side;    identifying a plurality of silence packets contained in the voice signal at the decoder side;    adapting to the plurality of silence packets by using an adaptation algorithm that adapts with time;    detecting a start of a silence segment at the decoder side; and    generating comfort noise at the decoder side, as specified by the adaptation algorithm at the start of the silence segment.    
     
     
         44 . The method of  claim 43 , further comprising the step of: 
 identifying a transition hangover between the voice signal and the silence segment at the decoder side wherein the silence segment comprises background noise and the transition hangover represents a wait time prior to the silence segment.    
     
     
         45 . The method of  claim 44 , wherein the adaptation algorithm further adapts to the transition hangover.  
     
     
         46 . The method of  claim 43 , wherein the adaptation algorithm comprises comfort noise adaptation that adapts to a plurality of silences packets in the voice signal between speech samples decoded by a decoder.  
     
     
         47 . The method of  claim 43 , wherein the adaptation algorithm generates a plurality of filter coefficients that adapt to a mean spectrum of background noise.  
     
     
         48 . The method of  claim 43 , further comprising a step of receiving only voice signals in the absence of silence insertion descriptors containing spectrum information.  
     
     
         49 . The method of  claim 43 , further comprising a step of receiving a noise floor wherein the noise floor is used, at least in part, for generating the comfort noise.  
     
     
         50 . The method of  claim 43 , wherein the adaptation algorithm approximates a spectrum of input noise using a least mean square algorithm.  
     
     
         51 . The method of  claim 50 , wherein the spectrum of input noise is approximately constant.  
     
     
         52 . The method of  claim 50 , wherein the adaptation algorithm performs an internal check to ascertain that the input noise is within 6 dB of a noise floor.  
     
     
         53 . The method of  claim 43 , wherein the adaptation algorithm generates colored comfort noise reflecting a spectrum of actual noise.  
     
     
         54 . A system for generating comfort noise at a decoder side in the absence of silence insertion description packets containing spectrum information transmitted by an encoder side, the system comprising: 
 a receiver for receiving a voice signal wherein the voice signal contains silence packets and identifying a plurality of silence packets contained in the voice signal at the decoder side;    an adaptation algorithm for adapting to the plurality of silence packets wherein the adaptation algorithm adapts with time;    a detector for detecting a start of a silence segment at the decoder side; and    a comfort noise generator for generating comfort noise at the decoder side, as specified by the adaptation algorithm at the start of the silence segment.    
     
     
         55 . The system of  claim 54 , further comprising: 
 a hangover identifier for identifying a transition hangover between the voice signal and the silence segment at the decoder side wherein the silence segment comprises background noise and the transition hangover represents a wait time prior to the silence segment.    
     
     
         56 . The system of  claim 55 , wherein the adaptation algorithm further adapts to the transition hangover.  
     
     
         57 . The system of  claim 54 , wherein the adaptation algorithm comprises comfort noise adaptation that adapts to a plurality of silences packets in the voice signal between speech samples decoded by a decoder.  
     
     
         58 . The system of  claim 54 , wherein the adaptation algorithm generates a plurality of filter coefficients that adapt to a mean spectrum of background noise.  
     
     
         59 . The system of  claim 54 , wherein the receiver receives only voice signals in the absence of silence insertion descriptors containing spectrum information.  
     
     
         60 . The system of  claim 54 , wherein the receiver receives a noise floor wherein the noise floor is used, at least in part, for generating the comfort noise.  
     
     
         61 . The system of  claim 54 , wherein the adaptation algorithm approximates a spectrum of input noise using a least mean square algorithm.  
     
     
         62 . The system of  claim 61 , wherein the spectrum of input noise is approximately constant.  
     
     
         63 . The system of  claim 61 , wherein the adaptation algorithm performs an internal check to ascertain that the input noise is within 6 dB of a noise floor.  
     
     
         64 . The system of  claim 54 , wherein the adaptation algorithm generates colored comfort noise reflecting a spectrum of actual noise.