Systems, methods, and apparatus for gain factor attenuation

• US 9,043,214 B2
• Filed: 04/21/2006
• Issued: 05/26/2015
• Est. Priority Date: 04/22/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Vos, Koen Bernard, Kandhadai, Ananthapadmanabhan Aasanipalai
• Primary Examiner(s): ROBERTS, SHAUN A
• Application Number:
  US11/408,511
• Publication Number:
  US 20060282262A1
• Time in Patent Office: 3,322 Days
• Field of Search: 704/223, 704/219, 704/500
• US Class Current: 704/500
• CPC Class Codes: G10L 19/0208 Subband vocoders
• CPC Class Codes: G10L 19/04 using predictive techniques
• CPC Class Codes: G10L 21/038 using band spreading techniques

Abstract

A method of signal processing according to one embodiment includes calculating an envelope of a first signal that is based on a low-frequency portion of a speech signal, calculating an envelope of a second signal that is based on a high-frequency portion of the speech signal, and calculating a plurality of gain factor values according to a time-varying relation between the envelopes of the first and second signal. The method includes attenuating, based on a variation over time of a relation between the envelopes of the first and second signals, at least one of the plurality of gain factor values. In one example, the variation over time of a relation between the envelopes is indicated by at least one distance among the plurality of gain factor values.

Claims

1. A method of signal processing, said method being implemented by a wireless communications device, the method comprising:

calculating an envelope of a first signal that is based on a low-frequency portion of a speech signal;

calculating an envelope of a second signal that is based on a high-frequency portion of the speech signal;

calculating a plurality of gain factor values according to a time-varying relation between the calculated envelopes, wherein each of the plurality of gain factor values is based on a calculated value of the time-varying relation over a different corresponding time period, and wherein the time-varying relation is one among a difference between the calculated envelopes and a ratio between the calculated envelopes;

calculating a value of a change in a relation between the calculated envelopes, wherein the change is a change over time; and

based on the calculated value of the change, attenuating at least one of the plurality of gain factor values.

2. The method of signal processing according to claim 1, wherein said first signal is based on an excitation signal derived from the low-frequency portion.

3. The method of signal processing according to claim 2, wherein said first signal is based on a spectral extension of the excitation signal.

4. The method of signal processing according to claim 2, said method comprising calculating a plurality of filter parameters according to the high-frequency portion,

wherein said first signal is based on the excitation signal and the plurality of filter parameters.

5. The method of signal processing according to claim 4, wherein said first signal is based on the plurality of filter parameters and a spectral extension of the excitation signal.

6. The method of signal processing according to claim 1, wherein each of the plurality of gain factor values is based on a square root of a ratio between the calculated envelopes over the corresponding time period.

7. The method of signal processing according to claim 1, wherein at least two among the plurality of gain factor values correspond to time periods that overlap.

8. The method of signal processing according to claim 1, wherein said calculated value of the change is based on at least one distance among the plurality of gain factor values.

9. The method of signal processing according to claim 1, wherein said calculated value of the change is based on a plurality of distances between gain factor values that correspond to successive time periods.

10. The method of signal processing according to claim 1, wherein said calculated value of the change is based on a sum of squared differences between gain factor values that correspond to successive time periods.

11. The method of signal processing according to claim 1, wherein said attenuating at least one of the plurality of gain factor values comprises:

calculating an attenuation factor value based on said calculated value of the change; and

at least one of (A) multiplying at least one of the plurality of gain factor values by the attenuation factor value and (B) adding the attenuation factor value to at least one of the plurality of gain factor values.

12. The method of signal processing according to claim 11, wherein said calculated value of the change is based on a plurality of distances between gain factor values that correspond to successive time periods.

13. The method of signal processing according to claim 1, said method comprising:

calculating a smoothing factor based on a sum of squared differences between gain factor values that correspond to successive time periods; and

smoothing at least one gain factor value according to the calculated smoothing factor.

14. The method of signal processing according to claim 13, wherein said attenuating at least one of the plurality of gain factor values comprises:

calculating an attenuation factor value based on said calculated smoothing factor; and

at least one of (A) multiplying at least one of the plurality of gain factor values by the attenuation factor value and (B) adding the attenuation factor value to at least one of the plurality of gain factor values.

15. The method of signal processing according to claim 1, said method comprising quantizing a second plurality of gain factor values resulting from said attenuating at least one of the plurality of gain factor values, wherein said quantizing includes:

calculating a quantization error; and

adding the quantization error to a value that is to be quantized.

16. The method of signal processing according to claim 1, wherein said evaluating a change includes calculating logarithms of gain factor values, and

wherein said calculated value of the change is based on said calculated logarithms.

17. The method of signal processing according to claim 1, wherein said attenuating at least one of the plurality of gain factor values comprises:

calculating an attenuation factor value based on said calculated value of the change; and

applying the attenuation factor value to each of the plurality of gain factor values that correspond to time periods within a frame of the speech signal.

18. An apparatus comprising:

a first envelope calculator configured and arranged to calculate an envelope of a first signal that is based on a low-frequency portion of a speech signal;

a second envelope calculator configured and arranged to calculate an envelope of a second signal that is based on a high-frequency portion of the speech signal;

a factor calculator configured and arranged to calculate a plurality of gain factor values according to a time-varying relation between the calculated envelopes, wherein each of the plurality of gain factor values is based on a calculated value of the time-varying relation over a different corresponding time period, and wherein the time-varying relation is one among a difference between the calculated envelopes and a ratio between the calculated envelopes; and

a gain factor attenuator configured and arranged to calculate a value of a change in a relation between the calculated envelopes, wherein the change is a change over time, and to attenuate at least one of the plurality of gain factor values based on the calculated value of the change.

19. The apparatus according to claim 18, wherein said first signal is based on a spectral extension of an excitation signal derived from the low-frequency portion.

20. The apparatus according to claim 18, wherein said factor calculator is configured to calculate each of the plurality of gain factor values based on a square root of a ratio between the calculated envelopes over the corresponding time period.

21. The apparatus according to claim 18, wherein said calculated value of the change is based on at least one distance among the plurality of gain factor values.

22. The apparatus according to claim 18, wherein said calculated value of the change is based on a plurality of distances between gain factor values that correspond to successive time periods.

23. The apparatus according to claim 18, wherein the gain factor attenuator comprises:

a variation calculator configured and arranged to calculate the calculated value of the change based on a plurality of differences among logarithms of the plurality of gain factor values; and

a factor calculator configured and arranged to calculate at least one attenuation factor value based on the calculated value of the change.

24. The apparatus according to claim 18, wherein said calculated value of the change is based on a plurality of distances among the plurality of gain factor values, and

wherein said gain factor attenuator is configured to calculate an attenuation factor value based on said calculated value of the change, and

wherein said gain factor attenuator includes a combiner configured to perform at least one of (A) multiplying at least one of the plurality of gain factor values by the attenuation factor value and (B) adding the attenuation factor value to at least one of the plurality of gain factor values.

25. The apparatus according to claim 18, said apparatus comprising a smoother configured to smooth at least one gain factor value according to a smoothing factor that is based on a sum of squared differences between successive ones of the plurality of gain factor values.

26. The apparatus according to claim 18, said apparatus including a cellular telephone configured to transmit a wireless signal including the at least one attenuated gain factor value.

27. The apparatus according to claim 18, wherein at least two among the plurality of gain factor values correspond to time periods that overlap.

28. The apparatus according to claim 18, wherein said gain factor attenuator is configured and arranged to calculate said value of the change based on a sum of squared differences between gain factor values that correspond to successive time periods.

29. An apparatus comprising:

means for calculating an envelope of a first signal that is based on a low-frequency portion of a speech signal;

means for calculating an envelope of a second signal that is based on a high-frequency portion of the speech signal;

means for calculating a plurality of gain factor values according to a time-varying relation between the calculated envelopes, wherein each of the plurality of gain factor values is based on a calculated value of the time-varying relation over a different corresponding time period, and wherein the time-varying relation is one among a difference between the calculated envelopes and a ratio between the calculated envelopes;

means for calculating a value of a change in a relation between the calculated envelopes, wherein the change is a change over time; and

means for attenuating at least one of the plurality of gain factor values based on the calculated value of the change.

30. The apparatus according to claim 29, wherein said first signal is based on a spectral extension of an excitation signal derived from the low-frequency portion.

31. The apparatus according to claim 29, wherein said means for calculating a plurality of gain factor values is configured to calculate each of the plurality of gain factor values based on a square root of a ratio between the calculated envelopes over the corresponding time period.

32. The apparatus according to claim 29, wherein said calculated value of the change is based on at least one distance among the plurality of gain factor values.

33. The apparatus according to claim 29, wherein said calculated value of the change is based on a plurality of distances between gain factor values that correspond to successive time periods.

34. The apparatus according to claim 29, wherein said means for attenuating comprises:

means for calculating the calculated value of the change based on a plurality of differences among logarithms of the plurality of gain factor values; and

means for calculating at least one attenuation factor value based on the calculated value of the change.

35. The apparatus according to claim 29, wherein said calculated value of the change is based on a plurality of distances among the plurality of gain factor values, and

wherein said means for attenuating is configured to calculate an attenuation factor value based on said calculated value of the change, and

wherein said means for attenuating includes means for combining configured to perform at least one of (A) multiplying at least one of the plurality of gain factor values by the attenuation factor value and (B) adding the attenuation factor value to at least one of the plurality of gain factor values.

36. The apparatus according to claim 29, said apparatus comprising means for smoothing configured to smooth at least one gain factor value according to a smoothing factor that is based on a sum of squared differences between successive ones of the plurality of gain factor values.

37. The apparatus according to claim 29, said apparatus including a cellular telephone configured to transmit a wireless signal including the at least one attenuated gain factor value.

38. The apparatus according to claim 29, wherein at least two among the plurality of gain factor values correspond to time periods that overlap.

39. The apparatus according to claim 29, wherein said means for calculating the value of the change is configured and arranged to calculate said value based on a sum of squared differences between gain factor values that correspond to successive time periods.

40. A non-transitory processor-readable medium having machine-executable instructions thereon, the instructions comprising:

code for calculating an envelope of a first signal that is based on a low-frequency portion of a speech signal;

code for calculating an envelope of a second signal that is based on a high-frequency portion of the speech signal;

code for calculating a plurality of gain factor values according to a time-varying relation between the calculated envelopes, wherein each of the plurality of gain factor values is based on a calculated value of the time-varying relation over a different corresponding time period, and wherein the time-varying relation is one among a difference between the calculated envelopes and a ratio between the calculated envelopes;

code for calculating a value of a change in a relation between the calculated envelopes, wherein the change is a change over time; and

code for attenuating at least one of the plurality of gain factor values based on the calculated value of the change.

41. The processor-readable medium according to claim 40, wherein at least two among the plurality of gain factor values correspond to time periods that overlap.

42. The processor-readable medium according to claim 40, wherein said code for calculating the value of the change is configured to calculate said value based on a sum of squared differences between gain factor values that correspond to successive time periods.