Encoding method and apparatus

• US 9,754,594 B2
• Filed: 06/01/2016
• Issued: 09/05/2017
• Est. Priority Date: 12/02/2013
• Status: Active Grant

• Current Assignee: Top Quality Telephony LLC
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Liu, Zexin, Wang, Bin, Miao, Lei
• Primary Examiner(s): Shah, Paras D
• Application Number:
  US15/170,524
• Publication Number:
  US 20160275955A1
• Time in Patent Office: 461 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 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/035 Scalar quantisation

Abstract

Present disclosure provide an encoding method and apparatus, which relate to the communications field and can perform proper quantization bit allocation for spectral coefficients of an audio signal, thereby improving quality of a signal obtained by a decoder by means of decoding. The method includes: after splitting spectral coefficients of a current data frame into subbands, acquiring quantized frequency envelope values of the subbands; modifying quantized frequency envelope values of subbands of a first quantity in the subbands; allocating quantization bits to the subbands according to modified quantized frequency envelope values of the subbands of the first quantity; quantizing a spectral coefficient of a subband to which a quantization bit is allocated in the subbands; and writing the quantized spectral coefficient of the subband to which a quantization bit is allocated into a bitstream.

Claims

1. An encoding method, comprising:

obtaining, by an encoder, an audio signal comprising a current data frame;

splitting, by the encoder, spectral coefficients of the current data frame into subbands;

acquiring, by the encoder, quantized frequency envelope values of the split subbands;

modifying, by the encoder, quantized frequency envelope values of subbands of a first quantity in the split subbands by acquiring modification factors, wherein the subbands of the first quantity are consecutive subbands and the consecutive subbands starting from a subband having a highest frequency of the current data frame;

allocating, by the encoder, quantization bits to the split subbands according to modified quantized frequency envelope values of the subbands of the first quantity;

quantizing, by the encoder, a spectral coefficient of a subband to which a quantization bit is allocated in the split subbands; and

writing, by the encoder, the quantized spectral coefficient of the subband to which the quantization bit is allocated into a bitstream.

2. The encoding method according to claim 1, wherein the modification factors of the subbands of the first quantity are acquired as follows:

acquiring signal types of the subbands of the first quantity; and

determining the modification factors of the subbands of the first quantity according to the acquired signal types.

3. The encoding method according to claim 2, wherein a modification factor of a first subband in the subbands of the first quantity is greater than 1 when a signal type of the first subband in the subbands of the first quantity is harmonic;

or

wherein a modification factor of a first subband in the subbands of the first quantity is less than or equal to 1 when a signal type of the first subband in the subbands of the first quantity is non-harmonic.

4. The encoding method according to claim 2, wherein the method further comprises:

acquiring stored reference information of subbands of a second quantity in a previous data frame of the current data frame, wherein the second quantity is less than or equal to the first quantity; and

determining the modification factors of the subbands of the first quantity according to the acquired signal types and the acquired reference information.

5. The encoding method according to claim 4, wherein the method of determining the modification factors of the subbands of the first quantity according to the signal types of the subbands of the first quantity and the reference information of the subbands of the second quantity comprises:

determining a first modification factor of the first subband according to the signal type of the first subband in the subbands of the first quantity;

determining a second modification factor of the first subband according to reference information of a second subband, corresponding to the first subband, in the subbands of the second quantity; and

using a product of the first modification factor and the second modification factor as the modification factor of the first subband.

6. The encoding method according to claim 5, wherein:

a value of the second modification factor is a value of a third modification factor when the reference information of the second subband comprises a quantization bit allocation status of the second subband;

or

a value of the second modification factor is a value of a fourth modification factor when the reference information of the second subband comprises a signal type of the second subband;

or

a value of the second modification factor is a product of a value of a third modification factor and a value of a fourth modification factor when the reference information of the second subband comprises a quantization bit allocation status of the second subband and a signal type of the second subband.

7. The encoding method according to claim 6, wherein:

when the quantization bit allocation status of the second subband indicates that no spectral coefficient is encoded, the third modification factor is less than 1, or when the quantization bit allocation status of the second subband indicates that a spectral coefficient is encoded, the third modification factor is greater than 1;

or

when the signal type of the second subband is harmonic, the fourth modification factor is greater than 1, or when the signal type of the second subband is non-harmonic, the fourth modification factor is less than or equal to 1.

8. The encoding method according to claim 6, wherein the second modification factor of the first subband is determined according to a ratio of any two values of a frequency envelope value of the second subband, an average frequency envelope value of the subbands of the second quantity, a bandwidth value of the subbands of the second quantity, a maximum value of frequency envelope values of the subbands of the second quantity, and a frequency envelope variance value of the subbands of the second quantity.

9. The encoding method according to claim 5, wherein the first modification factor of the first subband is determined according to a ratio of any two values of a frequency envelope value of the first subband, an average frequency envelope value of the subbands of the first quantity, a bandwidth value of the subbands of the first quantity, a maximum value of frequency envelope values of the subbands of the first quantity, and a frequency envelope variance value of the subbands of the first quantity.

10. The encoding method according to claim 1, wherein the acquiring modification factors of the subbands of the first quantity are acquired as follows:

acquiring stored reference information of subbands of a first quantity in a previous data frame of the current data frame; and

determining the modification factors of the subbands of the first quantity in the current data frame according to the reference information of the subbands of the first quantity in the previous data frame.

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

acquiring signal types of subbands of a third quantity in the subbands in the current data frame, wherein the third quantity is less than or equal to the first quantity; and

determining the modification factors of the subbands of the first quantity in the current data frame according to the reference information of the subbands of the first quantity in the previous data frame and the signal types of the subbands of the third quantity.

12. The encoding method according to claim 11, wherein the method of determining the modification factors of the subbands of the first quantity in the current data frame according to the reference information of the subbands of the first quantity in the previous data frame and the signal types of the subbands of the third quantity comprises:

determining a second modification factor of a first subband in the subbands of the first quantity in the current data frame according to reference information of a second subband in the subbands of the first quantity in the previous data frame;

determining a first modification factor of the first subband according to a signal type of the first subband; and

using a product of the first modification factor and the second modification factor as a modification factor of the first subband.

13. The encoding method according to claim 1, wherein the method further comprises:

storing reference information of the subbands of the first quantity in the current data frame.

14. An encoding apparatus, comprising:

a memory; and

a processor coupled to the memory and configured to;

obtain an audio signal comprising a current data frame;

split spectral coefficients of the current data frame into subbands;

acquire quantized frequency envelope values of the split subbands;

modify the quantized frequency envelope values of subbands of a first quantity in the split subbands by acquiring modification factors, wherein the subbands of the first quantity are consecutive subbands and the consecutive subbands starting from a subband having a highest frequency of the current data frame;

allocate quantization bits to the split subbands according to the modified quantized frequency envelope values of the subbands of the first quantity;

quantize a spectral coefficient of a subband to which a quantization bit is allocated in the split subbands; and

write the quantized spectral coefficient of the subband to which a quantization bit is allocated into a bitstream.

15. The encoding apparatus according to claim 14, wherein the processor is further configured to:

acquire signal types of the subbands of the first quantity; and

determine the modification factors of the subbands of the first quantity according to the acquired signal types of the subbands of the first quantity.

16. The encoding apparatus according to claim 15, wherein:

a modification factor of a first subband is greater than 1 when a signal type of the first subband in the subbands of the first quantity is harmonic;

or

a modification factor of a first subband is less than or equal to 1 when a signal type of the first subband in the subbands of the first quantity is non-harmonic.

17. The encoding apparatus according to claim 15, wherein the processor is further configured to:

acquire stored reference information of subbands of a second quantity in a previous data frame of the current data frame, wherein the second quantity is less than or equal to the first quantity; and

determine the modification factors of the subbands of the first quantity according to the acquired signal types of the subbands of the first quantity and the acquired reference information of the subbands of the second quantity.

18. The encoding apparatus according to claim 17, wherein the processor is further configured to:

determine a first modification factor of a first subband according to the acquired signal type of the first subband in the subbands of the first quantity;

determine a second modification factor of the first subband according to acquired reference information of a second subband, corresponding to the first subband, in the subbands of the second quantity; and

use a product of the first modification factor and the second modification factor as the modification factor of the first subband.

19. The encoding apparatus according to claim 18, wherein:

a value of the second modification factor is a value of a third modification factor when the reference information of the second subband comprises a quantization bit allocation status of the second subband;

or

a value of the second modification factor is a value of a fourth modification factor when the reference information of the second subband comprises a signal type of the second subband;

or

a value of the second modification factor is a product of a value of a third modification factor and a value of a fourth modification factor when the reference information of the second subband comprises a quantization bit allocation status of the second subband and a signal type of the second subband.

20. The encoding apparatus according to claim 19, wherein the processor is further configured to:

determine that the third modification factor is less than 1 when the quantization bit allocation status of the second subband indicates that no spectral coefficient is encoded, or determine that the third modification factor is greater than 1 when the quantization bit allocation status of the second subband indicates that a spectral coefficient is encoded;

or

determine that the fourth modification factor is greater than 1 when the signal type of the second subband is harmonic, or determine that the fourth modification factor is less than or equal to 1 when the signal type of the second subband is non-harmonic.

21. The encoding apparatus according to claim 19, wherein the second modification factor of the first subband is determined according to a ratio of any two values of a frequency envelope value of the second subband, an average frequency envelope value of the subbands of the second quantity, a bandwidth value of the subbands of the second quantity, a maximum value of frequency envelope values of the subbands of the second quantity, and a frequency envelope variance value of the subbands of the second quantity.

22. The encoding apparatus according to claim 18, wherein the first modification factor of the first subband is determined according to a ratio of any two values of a frequency envelope value of the first subband, an average frequency envelope value of the subbands of the first quantity, a bandwidth value of the subbands of the first quantity, a maximum value of frequency envelope values of the subbands of the first quantity, and a frequency envelope variance value of the subbands of the first quantity.

23. The encoding apparatus according to claim 14, wherein the processor is further configured to:

acquire reference information of subbands of a first quantity in a previous data frame of the current data frame; and

determine the modification factors of the subbands of the first quantity in the current data frame according to the acquired reference information of the subbands of the first quantity in the previous data frame.

24. The encoding apparatus according to claim 23, wherein the processor is further configured to:

acquire signal types of subbands of a third quantity in the subbands in the current data frame, wherein the third quantity is less than or equal to the first quantity; and

determine the modification factors of the subbands of the first quantity in the current data frame according to the acquired reference information of the subbands of the first quantity in the previous data frame and the signal types of the subbands of the third quantity.

25. The encoding apparatus according to claim 24, wherein the processor is further configured to:

determine a second modification factor of a first subband in the subbands of the first quantity in the current data frame according to reference information of a second subband in the subbands of the first quantity in the previous data frame;

determine a first modification factor of the first subband according to a signal type of the first subband; and

use a product of the first modification factor and the second modification factor as a modification factor of the first subband.

26. The encoding apparatus according to claim 14, wherein the processor is further configured to:

store reference information of the subbands of the first quantity in the current data frame.