Signal processing method and device

• US 10,546,591 B2
• Filed: 05/10/2019
• Issued: 01/28/2020
• Est. Priority Date: 04/29/2014
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Wang, Bin, Miao, Lei, Liu, Zexin
• Primary Examiner(s): Saint Cyr, Leonard
• Application Number:
  US16/409,290
• Publication Number:
  US 20190267015A1
• Time in Patent Office: 263 Days
• Field of Search: 704500-504
• CPC Class Codes: G10L 19/002 Dynamic bit allocation for perceptual audio coders G10L19/032
• CPC Class Codes: G10L 19/02 using spectral analysis, e.g. transform vocoders or subband vocoders
• CPC Class Codes: G10L 19/0204 using subband decomposition

Abstract

A signal processing method and device includes obtaining spectral coefficients of a current frame of an audio signal, in which N sub-bands of the current frame comprises at least one of the spectral coefficients. A total energy of M successive sub-bands of the N sub-bands, a total energy of K successive sub-bands of the N sub-bands, and an energy of a first sub-band are obtained to determine whether to modify original envelope values of the M sub-bands. When the original envelope values of the M sub-bands are modified, encoding bits are allocated to each of the N sub-bands according to the modified envelope values of the M sub-bands.

Claims

1. An audio signal processing method, comprising:

obtaining, by an audio signal encoder, spectral coefficients of a current frame of an audio signal, wherein each of N sub-bands of the current frame comprises at least one of the spectral coefficients, and N is a positive integer greater than 1;

obtaining, by the audio signal encoder, a total energy of M successive sub-bands of the N sub-bands, a total energy of K successive sub-bands of the N sub-bands, and an energy of a first sub-band, wherein the M sub-bands and the K sub-bands are separate and distinct, wherein M and K are positive integers, wherein N=M+K, and wherein the energy of the first sub-band is the largest among energies of the M sub-bands;

determining, by the audio signal encoder, whether to modify original envelope values of the M sub-bands based on the total energy of the M sub-bands, the total energy of the K sub-bands, and the energy of the first sub-band;

modifying, by the audio signal encoder, the original envelope values of the M sub-bands individually to obtain modified envelope values of the M sub-bands in response to determining that the original envelope values of the M sub-bands should be modified, wherein the modified envelope values of the M sub-bands is a determining factor for allocating encoding bits to the N sub-bands, and wherein at least one sub-band of the N sub-bands has at least one encoding bit allocated;

quantizing, by the audio signal encoder, spectral coefficients of each sub-band that has at least one encoding bit allocated using the at least one encoding bit; and

writing, by the audio signal encoder, the spectral coefficients of each sub-band that has the at least one encoding bit into a bitstream in response to quantizing the spectral coefficients of each sub-band that has at least one encoding bit.

2. The method according to claim 1, wherein determining, by the audio signal encoder, whether to modify the original envelope values of the M sub-bands based on the total energy of the M sub-bands, the total energy of the K sub-bands, and the energy of the first sub-band comprises determining whether the total energy of the M sub-bands is greater than the total energy of the K sub-bands multiplied by a first factor, the total energy of the M sub-bands is less than the total energy of the K sub-bands multiplied by a second factor, and the energy of the first sub-band multiplied by a third factor and further multiplied by M is greater than the total energy of the M sub-bands, wherein the first factor is less than the second factor, wherein it is determined to modify the original envelope values of the M sub-bands in response to a determination that the total energy of M sub-bands is greater than the total energy of the K sub-bands multiplied by the first factor, the total energy of the M sub-bands is less than the total energy of the K sub-bands multiplied by the second factor, and the energy of the first sub-band multiplied by the third factor and further multiplied by M is greater than the total energy of M sub-bands.

3. The method according to claim 2, wherein the first factor is ⅙

.

4. The method according to claim 2, wherein the second factor is ⅔

.

5. The method according to claim 2, wherein the third factor is 0.575 in response to an encoded bandwidth of the audio signal being between 0 to 4 Kilohertz (KHz), or wherein the third factor is 0.5 in response to the encoded bandwidth of the audio signal being between 0 to 8 KHz.

6. The method according to claim 1, wherein modifying the original envelope values of the M sub-bands individually to obtain the modified envelope values of the M sub-bands comprises:

determining, by the audio signal encoder, a modification factor for each of the M sub-bands based on the total energy of the M sub-bands and the energy of the first sub-band; and

modifying, by the audio signal encoder, the original envelope value of each of the M sub-bands using the modification factor, to obtain the modified envelope values of the M sub-bands.

7. The method according to claim 6, wherein the modification factor is determined according to the following equation:

8. The method according to claim 1, wherein the energy of the sub-band is determined according to the following equation:

9. An audio signal processing device, comprising:

a memory configured to store processor-executable instructions; and

a processor operatively coupled to the memory and configured to execute the processor-executable instructions to;

obtain spectral coefficients of a current frame of an audio signal, wherein each of N sub-bands of the current frame comprises at least one of the spectral coefficients, and N is a positive integer greater than 1;

obtain a total energy of M successive sub-bands of the N sub-bands, a total energy of K successive sub-bands of the N sub-bands, and an energy of a first sub-band, wherein the M sub-bands and the K sub-bands are separate and distinct, wherein M and K are positive integers, wherein N=M+K, and wherein the energy of the first sub-band is the largest among energies of the M sub-bands;

determine whether to modify original envelope values of the M sub-bands based on the total energy of the M sub-bands, the total energy of the K sub-bands, and the energy of the first sub-band;

modify the original envelope values of the M sub-bands individually to obtain modified envelope values of the M sub-bands in response to determining that the original envelope values of the M sub-bands should be modified, wherein the modified envelope values of the M sub-bands is a determining factor for allocating encoding bits to the N sub-bands, and wherein at least one sub-band of the N sub-bands has at least one encoding bit allocated;

quantize spectral coefficients of each sub-band that has at least one encoding bit allocated using the at least one encoding bit; and

write the spectral coefficients each sub-band that has the at least one encoding bit into a bitstream in response to quantizing the spectral coefficients of each sub-band that has at least one encoding bit.

10. The device according to claim 9, wherein in determining whether to modify the original envelope values of the M sub-bands based on the total energy of the M sub-bands, the total energy of the K sub-bands, and the energy of the first sub-band, the processor is configured to execute the processor-executable instructions to determine whether the total energy of the M sub-bands is greater than the total energy of the K sub-bands multiplied by a first factor, the total energy of the M sub-bands is less than the total energy of the K sub-bands multiplied by a second factor, and the energy of the first sub-band multiplied by a third factor and further multiplied by M is greater than the total energy of the M sub-bands, wherein the first factor is less than the second factor, wherein it is determined to modify the original envelope values of the M sub-bands in response to a determination that the total energy of the M sub-bands is greater than the total energy of the K sub-bands multiplied by the first factor, the total energy of the M sub-bands is less than the total energy of the K sub-bands multiplied by the second factor, and the energy of the first sub-band multiplied by the third factor and further multiplied by M is greater than the total energy of M sub-bands.

11. The device according to claim 10, wherein the first factor is ⅙

.

12. The device according to claim 10, wherein the second factor is ⅔

.

13. The device according to claim 10, wherein the third factor is 0.575 in response to an encoded bandwidth of the audio signal being between 0 to 4 Kilohertz (KHz), or the third factor is 0.5 in response to the encoded bandwidth of the audio signal being between 0 to 8 KHz.

14. The device according to claim 9, wherein in modifying the original envelope values of the M sub-bands individually to obtain the modified envelope values of the M sub-bands, the processor is configured to execute the processor-executable instructions to:

determine a modification factor for each of the M sub-bands based on the total energy of the M sub-bands and the energy of the first sub-band; and

modify the original envelope value of each of the M sub-bands using the modification factor to obtain the modified envelope values of the M sub-bands.

15. The device according to claim 14, wherein the processor is further configured to execute the processor-executable instructions to determine the modification factor according to the following equation:

16. The device according to claim 9, wherein the processor is further configured to execute the processor-executable instructions to determine the energy of the sub-band according to the following equation:

17. A non-transitory computer readable storage medium, embodying computer program code, which, when executed by a computer processor, causes the computer processor to be configured to:

obtain spectral coefficients of a current frame of an audio signal, wherein each of N sub-bands of the current frame comprises at least one of the spectral coefficients, and N is a positive integer greater than 1;

obtain a total energy of M successive sub-bands of the N sub-bands, a total energy of K successive sub-bands of the N sub-bands, and an energy of a first sub-band, wherein the M sub-bands and the K sub-bands are separate and distinct, wherein M and K are positive integers, wherein N=M+K, and wherein the energy of the first sub-band is the largest among energies of the M sub-bands;

determine whether to modify original envelope values of the M sub-bands based on the total energy of the M sub-bands, the total energy of the K sub-bands, and the energy of the first sub-band;

modify the original envelope values of the M sub-bands individually to obtain modified envelope values of the M sub-bands in response to determining that the original envelope values of the M sub-bands should be modified, wherein the modified envelope values of the M sub-bands is a determining factor for allocating encoding bits to the N sub-bands, and wherein at least one sub-band of the N sub-bands has at least one encoding bit allocated;

quantizespectral coefficients of each sub-band that has at least one encoding bit allocated using the at least one encoding bit; and

write the spectral coefficients of each sub-band that has the at least one encoding bit into a bitstream in response to quantizing the spectral coefficients of each sub-band that has at least one encoding bit.

18. The non-transitory computer readable storage medium according to claim 17, wherein the computer program code, when executed by the computer processor, further causes the computer processor to be configured to determine whether the total energy of the M sub-bands is greater than the total energy of the K sub-bands multiplied by a first factor, the total energy of the M sub-bands is less than the total energy of the K sub-bands multiplied by a second factor, and the energy of the first sub-band multiplied by a third factor and further multiplied by M is greater than the total energy of M sub-bands, wherein the first factor is less than the second factor, wherein it is determined to modify the original envelope values of the M sub-bands in response to a determination that the total energy of the M sub-bands is greater than the total energy of the K sub-bands multiplied by the first factor, the total energy of the M sub-bands is less than the total energy of the K sub-bands multiplied by the second factor, and the energy of the first sub-band multiplied by the third factor and further multiplied by M is greater than the total energy of the M sub-bands.

19. The non-transitory computer readable storage medium according to claim 18, wherein the first factor is ⅙

.

20. The non-transitory computer readable storage medium according to claim 18, wherein the second factor is ⅔

.

21. The non-transitory computer readable storage medium according to claim 18, wherein the third factor is 0.575 in response to an encoded bandwidth of the audio signal being between 0 to 4 Kilohertz (KHz) or the third factor is 0.5 in response to the encoded bandwidth of the audio signal being between 0 to 8 KHz.

22. The non-transitory computer readable storage medium according to claim 17, wherein the computer program code, when executed by the computer processor, further causes the computer processor to be configured to:

determine a modification factor for each of the M sub-bands based on the total energy of the M sub-bands and the energy of the first sub-band; and

modify the original envelope value of each of the M sub-bands using the modification factor, to obtain the modified envelope values of the M sub-bands.

23. The non-transitory computer readable storage medium according to claim 22, wherein the modification factor is determined according to the following equation:

24. The non-transitory computer readable storage medium according to claim 17, wherein the energy of the sub-band is determined according to the following equation: