System and Method for Processing an Audio Signal

Abstract

Systems and methods for audio signal processing are provided. In exemplary embodiments, a filter cascade of complex-valued filters are used to decompose an input audio signal into a plurality of frequency components or sub-band signals. These sub-band signals may be processed for phase alignment, amplitude compensation, and time delay prior to summation of real portions of the sub-band signals to generate a reconstructed audio signal.

1 . A method for processing audio signals, comprising:
 filtering an input signal with a complex-valued filter of a filter cascade to produce a first filtered signal;   subtracting the first filtered signal from the input signal to derive a first sub-band signal;   filtering the first filtered signal with a next complex-valued filter of the filter cascade to produce a next filtered signal; and   subtracting the next filtered signal from the first filtered signal to derive a next sub-band signal.   
     
     
         2 . The method of  claim 1  wherein the complex-valued filter and the next complex-valued filter are single pole, complex-valued filters. 
     
     
         3 . The method of  claim 1  further comprising performing phase alignment on one or more of the sub-band signals. 
     
     
         4 . The method of  claim 3  further comprising disposing of an imaginary portion of the one or more phase aligned sub-band signals. 
     
     
         5 . The method of  claim 1  further comprising performing amplitude compensation on one or more of the sub-band signals. 
     
     
         6 . The method of  claim 1  further comprising performing a time delay on one or more of the sub-band signals for cross-sub-band alignment. 
     
     
         7 . The method of  claim 6  further comprising summing the delayed one or more sub-band signals to generate a reconstructed audio signal. 
     
     
         8 . The method of  claim 1  further comprising pre-processing the input signal prior to filtering the input signal with the complex-valued filter of the filter cascade. 
     
     
         9 . The method of  claim 1  further comprising modifying one or more of the sub-band signals based on an analysis path from the filter cascade. 
     
     
         10 . The method of  claim 1  wherein the sub-band signals are frequency components of the input signal. 
     
     
         11 . A system for processing an audio signal, comprising:
 an audio processing engine comprising a filter cascade of complex-valued filters configured to derive a plurality of sub-band signals from an input signal, the set of complex-valued filters arranged in the filter cascade whereby an output of each complex-valued filter is passed to a next complex-valued filter in the filter cascade.   
     
     
         12 . The system of  claim 11  wherein the complex-valued filters are single pole, complex-valued filters. 
     
     
         13 . The system of  claim 11  wherein the audio processing engine further comprises a reconstruction module configured to perform phase alignment on one or more of the sub-band signals. 
     
     
         14 . The system of  claim 11  wherein the audio processing engine further comprises a reconstruction module configured to perform amplitude compensation on one or more of the sub-band signals. 
     
     
         15 . The system of  claim 11  wherein the audio processing engine further comprises a reconstruction module configured to perform a time delay on one or more of the sub-band signals. 
     
     
         16 . The system of  claim 11  wherein the audio processing engine further comprises a modification module configured to modify one or more of the sub-band signals based on an analysis path from the filter cascade. 
     
     
         17 . The system of  claim 11  further comprising a conditioning module configured to pre-process the input signal prior to filtering the input signal with the filter cascade. 
     
     
         18 . A machine-readable medium having embodied thereon a program, the program being executable by a machine to perform a method for processing an audio signal, the method comprising:
 filtering an input signal with a complex-valued filter of a filter cascade to produce a first filtered signal;   subtracting the first filtered signal from the input signal to derive a first sub-band signal;   filtering the first filtered signal with a next complex-valued filter of the filter cascade to produce a next filtered signal; and   subtracting the next filtered signal from the first filtered signal to derive a next sub-band signal.   
     
     
         19 . The machine-readable medium of  claim 18  wherein the complex-valued filter and the next complex-valued filter are single pole, complex-valued filters. 
     
     
         20 . The machine-readable medium of  claim 18  wherein the method further comprises performing phase alignment on one or more of the sub-band signals. 
     
     
         21 . The machine-readable medium of  claim 18  wherein the method further comprises performing amplitude compensation on one or more of the sub-band signals. 
     
     
         22 . The machine-readable medium of  claim 18  wherein the method further comprises performing a time delay on one or more the sub-band signals. 
     
     
         23 . The machine-readable medium of  claim 18  wherein the method further comprises pre-processing the input signal prior to filtering the input signal with the filter cascade.