AUDIO CODING METHOD AND RELATED APPARATUS

• US 20180268832A1
• Filed: 05/23/2018
• Published: 09/20/2018
• Est. Priority Date: 07/28/2014
• 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: Liu, Zexin, Miao, Lei
• Granted Patent: US 10,269,366 B2
• Time in Patent Office: Days
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/0208 Subband vocoders
• CPC Class Codes: G10L 19/0212 using orthogonal transformation
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders
• CPC Class Codes: G10L 19/22 Mode decision, i.e. based on audio signal content versus external parameters
• CPC Class Codes: G10L 25/18 the extracted parameters being spectral information of each sub-band
• CPC Class Codes: G10L 25/21 the extracted parameters being power information

Abstract

An audio encoding method and a related apparatus are disclosed. The audio coding method includes: obtaining an audio signal; obtaining spectral coefficients of a current frame of the audio signal; obtaining a set of reference coding parameters of the current frame; determining whether the set of reference coding parameters satisfy a preset parameter condition; when it is determined that the reference coding parameters satisfy the preset parameter condition, encoding the spectral coefficients of the current frame using a transform coded excitation (TCX) algorithm. The audio encoding method and the related apparatus help improve encoding quality or encoding efficiency in audio signal encoding.

Claims

1. An audio signal encoding method, comprising:

obtaining, by an audio signal encoder, an audio signal, wherein the audio signal comprises a plurality of subbands;

obtaining, by the audio signal encoder, spectral coefficients of a current frame of the audio signal;

obtaining, by the audio signal encoder, one or more reference coding parameters of the current frame based on the spectral coefficients;

determining, by the audio signal encoder, whether the reference coding parameters satisfy a preset parameter condition;

based on a determination that the reference coding parameters satisfy the preset parameter condition, encoding, by the audio signal encoder, the spectral coefficients using a transform coded excitation (TCX) algorithm.

2. The method according to claim 1, wherein the current frame comprises a subband a subband j, a subband x and a subband y;

wherein the reference coding parameters comprise;

a subband average energy of spectral coefficients in the subband i, and a subband average energy of spectral coefficients in the subband j;

wherein the highest frequency bin of the subband i is lower than the lowest frequency bin of the subband j, and the highest frequency bin of the subband j is higher than 8 kHz; and

a spectral peak of spectral coefficients in the subband x, a spectral average of the spectral coefficients in the subband x, a spectral peak of spectral coefficients in the subband y, and a spectral average of the spectral coefficients in the subband y;

wherein the highest frequency bin of the subband x is lower than the lowest frequency bin of the subband y;

and wherein the preset parameter condition comprises;

the subband average energy of the spectral coefficients in the subband j is greater than a product of the subband average energy of the spectral coefficients in the subband i multiplied by a constant T4; and

a first product of the spectral peak of the spectral coefficients in the subband x multipled by the spectral average of the spectral coefficients in the subband y is greater than a second product of the spectral peak of the spectral coefficients in the subband y multipled by the spectral average of the spectral coefficients in the subband x and multipled by a lowest value of an interval R1, and the first product is less than the second product multipled by a highest value of the interval R1.

3. The method according to claim 2, wherein the constant T4 is less than 1/1.2 and no less than 0.5.

4. The method according to claim 2, wherein a range of frequency bins of the subband j is 4.8 kHz to 9.6 kHz;

a range of frequency bins of the subband x is 1 kHz to 2.6 kHz; and

a range of frequency bins of the subband y is 4.8 kHz to 6.4 kHz.

5. The method according to claim 1, wherein the current frame comprises a subband a subband j, and a subband y;

wherein the highest frequency bin of the subband i is lower than the lowest frequency bin of the subband j, the highest frequency bin of the subband j is higher than a critical frequency bin F2, and F2 is in a range of 4.8 kHz to 8 kHz;

wherein the reference coding parameters comprise;

a subband average energy of spectral coefficients in the subband i, and a subband average energy of spectral coefficients in the subband j; and

a spectral peak of spectral coefficients in the subband y, and a spectral average of the spectral coefficients in the subband y;

wherein the preset parameter condition comprises;

the subband average energy of the spectral coefficients in the subband j is greater than a product of the subband average energy of the spectral coefficients in the subband i multipled by a constant T4; and

the spectral peak of the spectral coefficients in the subband y is less than a product of the spectral average of the spectral coefficients in the subband y multipled by a constant T45.

6. The method according to claim 5, wherein the constant T45 is 1.5.

7. The method according to claim 5, wherein a range of frequency bins of the subband j is 4.8 kHz to 9.6 kHz, and a range of frequency bins of the subband y is 4.8 kHz to 6.4 kHz.

8. The method according to claim 1, wherein the current frame comprises a subband x and a subband y, wherein the reference coding parameters comprise:

a spectral peak of spectral coefficients in the subband x, a spectral average of the spectral coefficients in the subband x, a spectral peak of spectral coefficients in the subband y, and a spectral average of the spectral coefficients in the subband y;

and wherein the preset parameter condition comprises;

a product of the spectral peak of the spectral coefficients in the subband x multipled by the spectral average of the spectral coefficients in the subband y is less than a product of the spectral peak of the spectral coefficients in the subband y multipled by the spectral average of the spectral coefficients in the subband x multipled by a constant T44; and

the spectral peak of the spectral coefficients in the subband y is greater than a product of the spectral average of the spectral coefficients in the subband y multipled by a constant T47.

9. The method according to claim 1, wherein the current frame comprises a subband x and a subband y;

wherein the reference coding parameters comprise;

a spectral peak of spectral coefficients in the subband x, a spectral average of the spectral coefficients in the subband x, a spectral peak of spectral coefficients in the subband y, and a spectral average of the spectral coefficients in the subband y;

and wherein the preset parameter condition comprises;

a product of the spectral peak of the spectral coefficients in the subband x multipled by the spectral average of the spectral coefficients in the subband y is greater than a product of the spectral peak of the spectral coefficients in the subband y multipled by the spectral average of the spectral coefficients in the subband x multipled by a constant T46; and

the spectral peak of the spectral coefficients in the subband y is less than a product of the spectral average of the spectral coefficients in the subband y multipled by a constant T45.

10. The method according to claim 9, wherein a value range of the constant T46 is 1.5 to 3.

11. An audio signal encoder, comprising:

a processor and a memory storing program instructions for execution by the processor;

wherein the processor is configured to execute the program instructions to;

obtain an audio signal, wherein the audio signal comprises a plurality of subbands;

obtain spectral coefficients of a current frame of the audio signal;

obtain one or more reference coding parameters of the current frame based on the spectral coefficients;

determine whether the reference coding parameters satisfy a preset parameter condition;

based on a determination that the reference coding parameters satisfy the preset parameter condition, encode the spectral coefficients using a transform coded excitation (TCX) algorithm.

12. The audio signal encoder according to claim 11, wherein the current frame comprises a subband i, a subband j, a subband x and a subband y;

wherein the reference coding parameters comprise;

a subband average energy of spectral coefficients in the subband i, and a subband average energy of spectral coefficients in the subband j;

wherein the highest frequency bin of the subband i is lower than the lowest frequency bin of the subband j, and the highest frequency bin of the subband j is higher than 8 kHz; and

a spectral peak of spectral coefficients in the subband x, a spectral average of the spectral coefficients in the subband x, a spectral peak of spectral coefficients in the subband y, and a spectral average of the spectral coefficients in the subband y;

wherein the highest frequency bin of the subband x is lower than the lowest frequency bin of the subband y;

and wherein the preset parameter condition comprise;

the subband average energy of the spectral coefficients in the subband j is greater than a product of the subband average energy of the spectral coefficients in the subband i multipled by a constant T4; and

a first product of the spectral peak of the spectral coefficients in the subband x multipled by the spectral average of the spectral coefficients in the subband y is greater than a second product of the spectral peak of the spectral coefficients in the subband y multipled by the spectral average of the spectral coefficients in the subband x and multipled by a lowest value of an interval R1, and the first product is less than the second product multipled by a highest value of the interval R1.

13. The audio signal encoder according to claim 12, wherein the constant T4 is less than 1/1.2 and no less than 0.5.

14. The audio signal encoder according to claim 12, wherein a range of frequency bins of the subband j is 4.8 kHz to 9.6 kHz;

a range of frequency bins of the subband x is 1 kHz to 2.6 kHz; and

a range of frequency bins of the subband y is 4.8 kHz to 6.4 kHz.

15. The audio signal encoder according to claim 11, wherein the current frame comprises a subband i, a subband j and a subband y;

wherein the highest frequency bin of the subband i is lower than the lowest frequency bin of the subband j, the highest frequency bin of the subband j is higher than a critical frequency bin F2, and F2 is in a range of 4.8 kHz to 8 kHz;

wherein the reference coding parameters comprise;

a subband average energy of spectral coefficients in the subband i, and a subband average energy of spectral coefficients in the subband j; and

a spectral peak of spectral coefficients in the subband y, and a spectral average of the spectral coefficients in the subband y;

wherein the preset parameter condition comprises;

the subband average energy of the spectral coefficients in the subband j is greater than a product of the subband average energy of the spectral coefficients in the subband i multipled by a constant T4; and

the spectral peak of the spectral coefficients in the subband y is less than a product of the spectral average of the spectral coefficients in the subband y multipled by a constant T45.

16. The audio signal encoder according to claim 15, wherein the constant T45 is 1.5.

17. The audio signal encoder according to claim 15, wherein a range of frequency bins of the subband j is 4.8 kHz to 9.6 kHz, and a range of frequency bins of the subband y is 4.8 kHz to 6.4 kHz.

18. The audio signal encoder according to claim 11, wherein the frequency band of the current frame comprises a subband x and a subband y;

wherein the reference coding parameters comprise;

a spectral peak of spectral coefficients in the subband x, a spectral average of the spectral coefficients in the subband x, a spectral peak of spectral coefficients in the subband y, and a spectral average of the spectral coefficients in the subband y;

and wherein the preset parameter condition comprises;

a product of the spectral peak of the spectral coefficients in the subband x multipled by the spectral average of the spectral coefficients in the subband y is less than a product of the spectral peak of the spectral coefficients in the subband y multipled by the spectral average of the spectral coefficients in the subband x multipled by a constant T44; and

the spectral peak of the spectral coefficients in the subband y is greater than a product of the spectral average of the spectral coefficients in the subband y multipled by a constant T47.

19. The audio signal encoder according to claim 11, wherein the frequency band of the current frame comprises a subband x and a subband y;

wherein the reference coding parameters comprise;

a spectral peak of spectral coefficients in the subband x, a spectral average of the spectral coefficients in the subband x, a spectral peak of spectral coefficients in the subband y, and a spectral average of the spectral coefficients in the subband y;

and wherein the preset parameter condition comprises;

a product of the spectral peak of the spectral coefficients in the subband x multipled by the spectral average of the spectral coefficients in the subband y is greater than a product of the spectral peak of the spectral coefficients in the subband y multipled by the spectral average of the spectral coefficients in the subband x multipled by a constant T46; and

the spectral peak of the spectral coefficients in the subband y is less than a product of the spectral average of the spectral coefficients in the subband y multipled by a constant T45.

20. The audio signal encoder according to claim 19, wherein a value range of the constant T46 is 1.5 to 3.