System and method for variable decorrelation of audio signals
View Patent ↗Various embodiments relate to a system and method for decorrelating an audio signal with a hybrid filter. The hybrid filter is generated by first generating a decorrelation filter. A frequency-dependent warping is applied to the decorrelation filter. The warped decorrelation filter is then mixed with a carrier filter to generate the hybrid filter. The carrier filter may include filters for spatial processing of an audio signal, filters for upmixing an audio signal, and/or filters for downmixing an audio signal.
1. A method for decorrelating an audio signal, comprising:
generating a decorrelation filter;
applying a frequency-dependent warping to the decorrelation filter to generate a warped decorrelation filter, wherein the frequency-dependent warping applies a frequency-dependent weighting to the phase of the decorrelation filter;
mixing the warped decorrelation filter with a carrier filter to generate a hybrid filter; and
processing an audio signal with the hybrid filter.
2. The method of claim 1 , wherein generating a decorrelation filter comprises:
generating a sequence of random numbers;
computing a fast Fourier transform (FFT) for the sequence of random numbers;
normalizing the magnitude of the FFT of the sequence of random numbers to unity; and
computing an inverse FFT of the normalized sequence of random numbers.
3. The method of claim 1 , wherein the frequency-dependent weighting decreases for higher frequencies.
4. The method of claim 1 , wherein mixing the carrier filter with the warped decorrelation filter comprises:
subtracting the phase of the warped decorrelation filter from the phase of the carrier filter to generate a hybrid filter phase.
5. The method of claim 4 , further comprising:
generating the hybrid filter by combining the magnitude of the carrier filter with the hybrid filter phase.
6. The method of claim 1 , wherein the carrier filter comprises:
at least one binaural room impulse response (BRIR) filter.
7. The method of claim 1 , wherein the carrier filter comprises:
at least one head related transfer function (HRTF) filter.
8. The method of claim 1 , wherein the carrier filter comprises:
at least one filter for upmixing an audio signal.
9. The method of claim 1 , wherein the carrier filter comprises:
at least one filter for downmixing an audio signal.
10. A non-transitory processor-readable storage medium having instructions stored thereon that cause one or more processors to perform a method of decorrelating an audio signal, the method comprising:
generating a decorrelation filter;
applying a frequency-dependent warping to the decorrelation filter to generate a warped decorrelation filter, wherein the frequency-dependent warping applies a frequency-dependent weighting to the phase of the decorrelation filter;
mixing the warped decorrelation filter with a carrier filter to generate a hybrid filter; and
processing an audio signal with the hybrid filter.
11. The non-transitory processor-readable storage medium of claim 10 , wherein generating a decorrelation filter comprises:
generating a sequence of random numbers;
computing a fast Fourier transform (FFT) for the sequence of random numbers;
normalizing the magnitude of the FFT of the sequence of random numbers to unity; and
computing an inverse FFT of the normalized sequence of random numbers.
12. The non-transitory processor-readable storage medium of claim 11 , wherein the frequency-dependent weighting decreases for higher frequencies.
13. The non-transitory processor-readable storage medium of claim 10 , wherein mixing the carrier filter with the warped decorrelation filter comprises:
subtracting the phase of the warped decorrelation filter from the phase of the carrier filter to generate a hybrid filter phase.
14. The non-transitory processor-readable storage medium of claim 13 , wherein mixing the carrier filter with the warped decorrelation filter further comprises:
generating the hybrid filter by combining the magnitude of the carrier filter with the hybrid filter phase.
15. The non-transitory processor-readable storage medium of claim 10 , wherein the carrier filter comprises:
at least one binaural room impulse response (BRIR) filter.
16. The non-transitory processor-readable storage medium of claim 10 , wherein the carrier filter comprises:
at least one head related transfer function (HRTF) filter.
17. The non-transitory processor-readable storage medium of claim 10 , wherein the carrier filter comprises:
at least one filter for upmixing an audio signal.
18. The non-transitory processor-readable storage medium of claim 10 , wherein the carrier filter comprises:
at least one filter for downmixing an audio signal.