Audio signal processing

• US 10,142,763 B2
• Filed: 11/24/2014
• Issued: 11/27/2018
• Est. Priority Date: 11/27/2013
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Shuang, Zhiwei, McGrath, David S., Mason, Michael W.
• Primary Examiner(s): Patel, Yogeshkumar
• Application Number:
  US15/039,695
• Publication Number:
  US 20170026771A1
• Time in Patent Office: 1,464 Days
• Field of Search: 704500, 381 17, 381 56, 381 943, 381103, 381 2
• CPC Class Codes: H03G 9/005 of digital or coded signals
• CPC Class Codes: H03G 9/025 frequency-dependent volume compression or expansion, e.g. multiple-band systems H03G9/10, H03G9/18 take precedence
• CPC Class Codes: H04S 2420/01 Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
• CPC Class Codes: H04S 2420/07 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04S 7/306 For headphones
• CPC Class Codes: H04S 7/307 Frequency adjustment, e.g. tone control H04S7/301 takes precedence

Abstract

Embodiments of the present invention relate to audio signal processing. Specifically, a method for processing audio signal is provided, the method comprising: determining, for a current frame of the audio signal, frequency band energies for a plurality of predefined frequency bands at least partially based on frequency parameters of the current frame; generating frequency band gains for the plurality of predefined frequency bands by processing the frequency band energies; and generating frequency bin gains for the current frame based on the frequency band gains using predefined frequency band filter banks, the frequency band filter banks being specific to the plurality of predefined frequency bands. Corresponding system and computer program product are also disclosed.

Claims

1. A method for processing audio signal, the method comprising:

determining, for a current frame of the audio signal, frequency band energies for a plurality of predefined frequency bands at least partially based on frequency parameters of the current frame;

generating frequency band gains for the plurality of predefined frequency bands by processing the frequency band energies;

generating frequency bin gains for the current frame based on the frequency band gains using predefined frequency band filter banks, the frequency band filter banks being specific to the plurality of predefined frequency bands; and

applying headphone virtualization to the audio signal by convolving the audio signal with a head-related impulse response (HRIR) associated with the audio signal,

wherein the HRIR is integrated into the predefined frequency band filter banks, and wherein the convolving comprises;

convolving the audio signal with the HRIR in a frequency domain using the predefined frequency band filter banks.

2. The method according to claim 1, wherein determining the frequency band energies comprises:

transforming the current frame from a time domain to the frequency domain to obtain a plurality of frequency bins;

associating each of the frequency bands with at least one of the frequency bins; and

determining the frequency band energy for each of the frequency bands based on the frequency parameters corresponding to the associated at least one frequency bin.

3. The method according to claim 2, wherein transforming the current frame comprises applying time domain crossfading to the current frame.

4. The method according to claim 1, wherein the frequency band energies for one or more of the frequency bands are determined based on the respective frequency parameters of the current frame and at least one previous frame of the audio signal.

5. The method according to claim 4, wherein the one or more frequency bands include at least one low frequency band among the plurality of predefined frequency bands.

6. The method according to claim 1, wherein generating the frequency band gains comprises applying at least one of the following on the frequency band energies:

equalizer processing, regulator processing, and peak limiting processing.

7. The method according to claim 1, wherein the frequency band gains are generated by processing the frequency band energies according to a parameter of a playback device for playing back the audio signal.

8. The method according to claim 1, further comprising:

generating frequency domain output for the current frame at least partially based on the frequency bin gains for the current frame.

9. The method according to claim 8, wherein the frequency domain output for the current frame is generated based on the respective frequency bin gains for the current frame and at least one previous frame of the audio signal.

10. The method according to claim 8, further comprising:

applying frequency domain crossfading to the frequency domain output;

transforming the frequency domain output into a time domain to generate time domain output for the current frame;

applying time domain crossfading to the generated time domain output; and

limiting the time domain output with a predefined peak threshold.

11. The method according to claim 10, wherein the convolving comprises:

convolving the audio signal with the HRIR in the time domain.

12. The method according to claim 11, further comprising:

modifying the determined frequency band energies at least partially based on the HRIR.

13. The method according to claim 10, further comprising:

applying at least one of room equalization and reverberation to the audio signal.

14. The method according to claim 10, wherein the audio signal is convolved with the HRIR based on a symmetry of channels of the audio signal.

15. The method according to claim 14, wherein the convolving comprises:

converting the audio signal according to the symmetry of the channels;

converting the HRIR according to the symmetry of the channels; and

convolving the converted audio signal and the converted HRIR.

31. A computer program product for processing audio signal, the computer program product being tangibly stored on a non-transient computer readable medium and comprising machine executable instructions which, when executed, cause the machine to perform steps of the method according to claim 1.

16. A system for processing audio signal, the system comprising:

a band energy determining unit configured to determine, for a current frame of the audio signal, frequency band energies for a plurality of predefined frequency bands at least partially based on frequency parameters of the current frame;

a band gain generating unit configured to generate frequency band gains for the plurality of predefined frequency bands by processing the frequency band energies;

a bin gain generating unit configured to generate frequency bin gains for the current frame based on the frequency band gains using predefined frequency band filter banks, the frequency band filter banks being specific to the plurality of predefined frequency bands; and

a headphone virtualization unit configured to apply headphone virtualization to the audio signal by convolving the audio signal with a head-related impulse response (HRIR) associated with the audio signal,

wherein the HRIR is integrated into the predefined frequency band filter banks, and

wherein the convolving comprises;

convolving the audio signal with the HRIR in a frequency domain using the predefined frequency band filter banks.

17. The system according to claim 16, further comprising:

a time-frequency transforming unit configured to transform the current frame from a time domain to the frequency domain to obtain a plurality of frequency bins; and

an associating unit configured to associate each of the frequency bands with at least one of the frequency bins,

wherein the band energy determining unit is configured to determine the frequency band energy for each of the frequency bands based on the frequency parameters corresponding to the associated at least one frequency bin.

18. The system according to claim 17, further comprising:

a first time domain crossfading unit configured to apply time domain crossfading to the current frame.

19. The system according to claim 16, wherein the frequency band energies for one or more of the frequency bands are determined based on the respective frequency parameters of the current frame and at least one previous frame of the audio signal.

20. The system according to claim 19, wherein the one or more frequency bands include at least one low frequency band among the plurality of predefined frequency bands.

21. The system according to claim 16, wherein the band gain generating unit comprises at least one of:

an equalizer, a regulator, and a peak limiter.

22. The system according to claim 16, wherein the band gain generating unit comprises a device specific processing unit configured to generate the frequency band gains by processing the frequency band energies according to a parameter of a playback device for playing back the audio signal.

23. The system according to claim 16, further comprising:

a frequency domain output generating unit configured to generate frequency domain output for the current frame at least partially based on the frequency bin gains for the current frame.

24. The system according to claim 23, wherein the frequency domain output generating unit comprises a unit configured to generate the frequency domain output for the current frame based on the respective frequency bin gains for the current frame and at least one previous frame of the audio signal.

25. The system according to claim 23, further comprising:

a frequency domain crossfading unit configured to apply frequency domain crossfading to the frequency domain output;

a frequency-time transforming unit configured to transform the frequency domain output into a time domain to generate time domain output for the current frame;

a second time domain crossfading unit configured to apply time domain crossfading to the generated time domain output; and

a peak limiting unit configured to limit the time domain output with a predefined peak threshold.

26. The system according to claim 25, wherein the headphone virtualization unit comprises:

a time domain convolving unit configured to convolve the audio signal with the HRIR in the time domain.

27. The system according to claim 16, further comprising:

a band energy modifying unit configured to modify the determined frequency band energies at least partially based on the HRIR.

28. The system according to claim 25, further comprising at least one of:

a room equalizing unit configured to apply room equalization to the audio signal; and

a reverberating unit configured to apply reverberation to the audio signal.

29. The system according to claim 25, wherein the audio signal is convolved with the HRIR based on symmetry of channels of the audio signal.

30. The system according to claim 29, wherein the headphone virtualization unit comprises:

an audio signal converting unit configured to convert the audio signal according to the symmetry of the channels; and

a HRIR converting unit configured to convert the HRIR according to the symmetry of the channels,

wherein the headphone virtualization unit is configured to convolve the converted audio signal and the converted HRIR.