Compressed domain universal transcoder

Abstract

The system and method of the present invention comprises a compressed domain universal transcoder that transcodes a bit stream representing frames of data encoded according to a first compression standard to a bit stream representing frames of data according to a second compression standard. The method includes decoding a bit stream into a first set of parameters compatible with a first compression standard. Next, the first set of parameters are transformed into a second set of parameters compatible with a second compression standard without converting the first set of parameters to an analog or digital waveform representation. Lastly, the second set of parameters are encoded into a bit stream compatible with the second compression standard.

1 . A method for transcoding a bit stream representing frames of speech encoded according to a first vocoder standard to a bit stream representing frames of speech encoded according to a second vocoder standard, comprising: 
 decoding a bit stream into a first set of vocoder parameters compatible with a first vocoder standard;    transforming the first set of vocoder parameters into a second set of vocoder parameters compatible with a second vocoder standard without converting the first set of vocoder parameters to an analog or digital waveform representation; and    encoding the second set of vocoder parameters into a bit stream compatible with the second vocoder standard.    
   
   
       2 . The method of  claim 1 , wherein the decoding, transforming, and encoding are performed in real time.  
   
   
       3 . The method of  claim 1 , wherein the first and second sets of vocoder parameters include spectral parameters, voicing parameters, gain parameters, and pitch parameters.  
   
   
       4 . The method of  claim 1 , wherein the first and second vocoders standards are one of linear predictive coding (LPC), mixed excitation linear predictive (MELP) coding, and time domain voicing cutoff (TDVC).  
   
   
       5 . The method of  claim 1 , further including: 
 synthesizing the encoded bit stream representing the second set of vocoder parameters into an analog speech signal.    
   
   
       6 . A method for transcoding data, comprising: 
 receiving first parametric data encoded according to a first encoding standard; and    transforming the first parametric data to second parametric data encoded according to a second encoding standard, wherein the transforming occurs without converting the parametric data to an analog or digital waveform representation.    
   
   
       7 . The method of  claim 6 , wherein the first parametric data and second parametric data represent encoded speech.  
   
   
       8 . The method of  claim 6 , wherein the transforming is performed in real time.  
   
   
       9 . The method of  claim 6 , wherein the first parametric data and second parametric data include spectral parameters, voicing parameters, gain parameters, and pitch parameters.  
   
   
       10 . The method of  claim 6 , wherein the first and second encoding standards are one of linear predictive coding (LPC), mixed excitation linear predictive (MELP) coding, and time domain voicing cutoff (TDVC).  
   
   
       11 . The method of  claim 6 , further comprising: 
 encoding the second parametric data into a bit stream according to the second encoding standard.    
   
   
       12 . A method of converting data from a first compressed format to a second compressed format, comprising: 
 receiving a data stream in a first compressed format; and    transforming the data stream to a second compressed format without performing decompression of the data.    
   
   
       13 . The method of  claim 12 , wherein the converting is performed in real time.  
   
   
       14 . The method of  claim 12 , wherein the data stream represents parametric data.  
   
   
       15 . The method of  claim 12 , wherein the data stream in the first compressed format represents encoded speech.  
   
   
       16 . The method of  claim 12 , wherein the data stream contains spectral parameters, voicing parameters, gain parameters, and pitch parameters.  
   
   
       17 . The method of  claim 12 , wherein the first and second compressed formats are one of linear predictive coding (LPC), mixed excitation linear predictive (MELP) coding, and time domain voicing cutoff (TDVC).  
   
   
       18 . The method of  claim 17 , further comprising: 
 encoding the data stream into a bit stream according to the second compressed format, after transforming the data stream to the second compressed format.    
   
   
       19 . A transcoder for transcoding a bit stream representing frames of speech encoded according to a first vocoder standard to a bit stream representing frames of speech encoded according to a second vocoder standard, comprising: 
 a decoder decoding a bit stream into a first set of vocoder parameters compatible with a first vocoder standard;    a conversion unit transforming the first set of vocoder parameters into a second set of vocoder parameters compatible with a second vocoder standard without converting the first set of vocoder parameters to an analog or digital waveform representation; and    an encoder encoding the second set of vocoder parameters into a bit stream compatible with the second vocoder standard.    
   
   
       20 . A method for transcoding a bit stream representing frames of data encoded according to a first compression standard to a bit stream representing frames of data encoded according to a second compression standard, comprising: 
 decoding a bit stream into a first set of parameters compatible with a first compression standard;    transforming the first set of parameters into a second set of parameters compatible with a second compression standard without converting the first set of parameters to an analog or digital waveform representation; and    encoding the second set of parameters into a bit stream compatible with the second compression standard.