Online dereverberation algorithm based on weighted prediction error for noisy time-varying environments
First Claim
1. A method for processing multichannel audio signals comprising:
- receiving an input signal comprising a time-domain, multi-channel audio signal;
transforming the input signal to a frequency domain input signal comprising a plurality of multi-channel frequency domain, k-spaced under-sampled subband signals;
buffering and delaying each channel of the frequency domain input signal;
saving a subset of spectral frames for prediction filter estimation at each of the spectral frames;
estimating a variance of the frequency domain input signal at each of the spectral frames;
adaptively estimating a prediction filter in an online manner by using a recursive least squares (RLS) algorithm and a cost function based at least in part on the estimated variance;
linearly filtering each channel of the frequency domain input signal to reduce reverberation using the estimated prediction filter to produce a linearly filtered output signal;
nonlinearly filtering the linearly filtered output signal to reduce residual reverberation using the estimated variances, producing a nonlinearly filtered output signal; and
synthesizing the nonlinearly filtered output signal to reconstruct a dereverberated time-domain, multi-channel audio signal, wherein a number of output channels is equal to a number of input channels.
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Abstract
Systems and methods for processing multichannel audio signals include receiving a multichannel time-domain audio input, transforming the input signal to plurality of multi-channel frequency domain, k-spaced under-sampled subband signals, buffering and delaying each channel, saving a subset of spectral frames for prediction filter estimation at each of the spectral frames, estimating a variance of the frequency domain signal at each of the spectral frames, adaptively estimating the prediction filter in an online manner using a recursive least squares (RLS) algorithm, linearly filtering each channel using the estimated prediction filter, nonlinearly filtering the linearly filtered output signal to reduce residual reverberation and the estimated variances, producing a nonlinearly filtered output signal, and synthesizing the nonlinearly filtered output signal to reconstruct a dereverberated time-domain multi-channel audio signal.
11 Citations
20 Claims
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1. A method for processing multichannel audio signals comprising:
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receiving an input signal comprising a time-domain, multi-channel audio signal; transforming the input signal to a frequency domain input signal comprising a plurality of multi-channel frequency domain, k-spaced under-sampled subband signals; buffering and delaying each channel of the frequency domain input signal; saving a subset of spectral frames for prediction filter estimation at each of the spectral frames; estimating a variance of the frequency domain input signal at each of the spectral frames; adaptively estimating a prediction filter in an online manner by using a recursive least squares (RLS) algorithm and a cost function based at least in part on the estimated variance; linearly filtering each channel of the frequency domain input signal to reduce reverberation using the estimated prediction filter to produce a linearly filtered output signal; nonlinearly filtering the linearly filtered output signal to reduce residual reverberation using the estimated variances, producing a nonlinearly filtered output signal; and synthesizing the nonlinearly filtered output signal to reconstruct a dereverberated time-domain, multi-channel audio signal, wherein a number of output channels is equal to a number of input channels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An audio processing system comprising:
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an audio input operable to receive a time-domain, multi-channel audio signal; a subband decomposition module operable to transform the input signal to a frequency domain input signal comprising a plurality of multi-channel frequency domain, k-spaced under-sampled subband signals; a buffer operable to buffer and delay each channel of the frequency domain input signal, saving a subset of spectral frames for prediction filter estimation at each of the spectral frames; a variance estimator operable to estimate a variance of the frequency domain input signal at each of the spectral frames; a prediction filter estimator operable to adaptively estimate the prediction filter in an online manner by using a recursive least squares (RLS) algorithm having a cost function based at least in part on the estimated variance; a linear filter operable to linearly filter each channel of the frequency domain input signal to reduce reverberation using the estimated prediction filter to produce a linearly filtered output signal; a non-linear filter operable to nonlinearly filter the linearly filtered output signal to reduce residual reverberation using the estimated variances, producing a nonlinearly filtered output signal; and a synthesizer operable to synthesize the nonlinearly filtered output signal to reconstruct a dereverberated time-domain, multi-channel audio signal, wherein a number of output channels is equal to a number of input channels. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification