Audio signal encoding method and mobile phone

• US 10,706,866 B2
• Filed: 10/30/2019
• Issued: 07/07/2020
• 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
• Primary Examiner(s): Cyr, Leonard Saint
• Application Number:
  US16/668,177
• Publication Number:
  US 20200066290A1
• Time in Patent Office: 251 Days
• Field of Search: 704500-504
• 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 signal encoding method and a mobile phone, where the audio signal encoding method includes obtaining a digital audio signal in time domain; transforming the digital audio signal in time domain to an audio signal in frequency domain, which comprises a current frame comprises a plurality of subbands; obtaining, reference parameters of the plurality of subbands; encoding, using a HQ algorithm, the current frame to obtain an encoded audio signal when the reference parameters meet a preset parameter condition; and transmitting the encoded audio signal via a network. The audio signal encoding method and the mobile phone help improve encoding quality or encoding efficiency in audio signal encoding.

Claims

1. An audio signal encoding method, comprising:

obtaining, by a mobile phone, a digital audio signal in time domain;

transforming, by the mobile phone, the digital audio signal in time domain to an audio signal in frequency domain, wherein the audio signal in frequency domain comprises a current frame, and the current frame comprises a subband i, a subband j, a subband x and a subband y;

obtaining, by the mobile phone, an average energy of the subband i, an average energy of the subband j, a spectral peak of the subband x, a spectral average of the subband x, a spectral peak of the subband y, and a spectral average of the subband y;

encoding, by the mobile phone and using a high quality transform coding (HQ) algorithm, the current frame to obtain an encoded audio signal when the average energy of the subband j is greater than a product of the average energy of the subband i multiplied by a first constant (T4), a product of the spectral peak of the subband x multiplied by the spectral average of the subband y is greater than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x and multiplied by a lowest value of a first interval (R1), and the product of the spectral peak of the subband x multiplied by the spectral average of the subband y is less than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x and multiplied by a highest value of the R1; and

transmitting, by the mobile phone, the encoded audio signal via a network.

2. The audio signal encoding method of claim 1, wherein a highest frequency bin of the subband i is lower than a lowest frequency bin of the subband j, wherein a highest frequency bin of the subband j is higher than eight (8) kilohertz (kHz), and wherein a highest frequency bin of the subband x is lower than a lowest frequency bin of the subband y.

3. The audio signal encoding method of claim 1, wherein the constant T4 is less than one (1) divided by one point two (1.2) and greater than or equal to zero point five (0.5).

4. The audio signal encoding method of claim 1, wherein a lowest frequency bin of a range of frequency bins of the subband i is zero point four (0.4) kilohertz (kHz), wherein a range of frequency bins of the subband j is four point eight (4.8) kHz to nine point six (9.6) kHz, wherein a range of frequency bins of the subband x is one (1) kHz to two point six (2.6) kHz, and wherein a range of frequency bins of the subband y is four point eight (4.8) kHz to six point four (6.4) kHz.

5. The audio signal encoding method of claim 1, wherein the obtaining the digital audio signal in time domain comprises:

obtaining an analog audio signal; and

converting the analog audio signal into a digital audio signal in time domain.

6. An audio signal encoding method, comprising:

obtaining, by a mobile phone, a digital audio signal in time domain;

transforming, by the mobile phone, the digital audio signal in time domain to an audio signal in frequency domain, wherein the audio signal in frequency domain comprises a current frame, and the current frame comprises a subband i, a subband j, a subband x and a subband y;

obtaining, by the mobile phone, an average energy of the subband i, an average energy of the subband j, a spectral peak of the subband x, a spectral average of the subband x, a spectral peak of the subband v, and a spectral average of the subband y;

encoding, by the mobile phone and using a high quality transform coding (HQ) algorithm, the current frame to obtain an encoded audio signal when;

a product of the spectral peak of the subband x multiplied by the spectral average of the subband y is less than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x multiplied by a first constant (T44), and the spectral peak of the subband y is greater than a product of the spectral average of the subband y multiplied by a second constant (T45);

or

the product of the spectral peak of the subband x multiplied by the spectral average of the subband y is greater than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x multiplied by a third constant (T46), and the spectral peak of the subband y is less than a product of the spectral average of the subband y multiplied by the T45; and

transmitting, by the mobile phone, the encoded audio signal via a network.

7. The audio signal encoding method of claim 6, wherein the T45 is one point five (1.5).

8. The audio signal encoding method of claim 6, wherein a range of frequency bins of the subband x is one (1) kilohertz (kHz) to two point six (2.6) kHz, and wherein a range of frequency bins of the subband y is four point eight (4.8) kHz to six point four (6.4) kHz.

9. A mobile phone, comprising:

a hardware circuit, configured to obtain a digital audio signal in time domain;

a memory storing program instructions; and

at least one processor coupled to the memory, wherein the program instructions cause the at least one processor to be configured to;

transform the digital audio signal in time domain to an audio signal in frequency domain, wherein the audio signal in frequency domain comprises a current frame, and the current frame comprises a subband i, a subband j, a subband x and a subband y;

obtain an average energy of the subband i, an average energy of the subband j, a spectral peak of the subband x, a spectral average of the subband x, a spectral peak of the subband y, and a spectral average of the subband y; and

encode, using a high quality transform coding (HQ) algorithm, the current frame to obtain an encoded audio signal when the average energy of the subband j is greater than a product of the average energy of the subband i multiplied by a first constant (T4), a product of the spectral peak of the subband x multiplied by the spectral average of the subband y is greater than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x and multiplied by a lowest value of a first interval (R1), and the product of the spectral peak of the subband x multiplied by the spectral average of the subband y is less than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x and multiplied by a highest value of the R1; and

a network interface, configured to transmit the encoded audio signal via a network.

10. The mobile phone of claim 9, wherein a highest frequency bin of the subband i is lower than a lowest frequency bin of the subband j, wherein a highest frequency bin of the subband j is higher than eight (8) kilohertz (kHz), and wherein a highest frequency bin of the subband x is lower than a lowest frequency bin of the subband y.

11. The mobile phone of claim 9, wherein the constant T4 is less than one (1) divided by one point two (1.2) and greater than or equal to zero point five (0.5).

12. The mobile phone of claim 9, wherein a lowest frequency bin of a range of frequency bins of the subband i is zero point four (0.4) kilohertz (kHz), wherein a range of frequency bins of the subband j is four point eight (4.8) kHz to nine point six (9.6) kHz, wherein a range of frequency bins of the subband x is one (1) kHz to two point six (2.6) kHz, and wherein a range of frequency bins of the subband y is four point eight (4.8) kHz to six point four (6.4) kHz.

13. The mobile phone of claim 9, wherein the hardware circuit comprises:

a microphone, configured to obtain an analog audio signal; and

an analog-digital convertor, configured to covert the analog audio signal into a digital audio signal in time domain.

14. A mobile phone, comprising:

a hardware circuit, configured to obtain a digital audio signal in time domain;

a memory storing program instructions; and

at least one processor coupled to the memory, wherein the program instructions cause the at least one processor to be configured to;

transform the digital audio signal in time domain to an audio signal in frequency domain, wherein the audio signal in frequency domain comprises a current frame, and the current frame comprises a subband i, a subband j, a subband x and a subband y;

obtain an average energy of the subband i, an average energy of the subband j, a spectral peak of the subband x, a spectral average of the subband x, a spectral peak of the subband y, and a spectral average of the subband y; and

encode, using a high quality transform coding (HQ) algorithm, the current frame to obtain an encoded audio signal when;

a product of the spectral peak of the subband x multiplied by the spectral average of the subband y is less than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x multiplied by a first constant (T44), and the spectral peak of the subband y is greater than a product of the spectral average of the subband y multiplied by a second constant (T45);

or

the product of the spectral peak of the subband x multiplied by the spectral average of the subband y is greater than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x multiplied by a third constant (T46), and the spectral peak of the subband y is less than a product of the spectral average of the subband y multiplied by the T45; and

a network interface, configured to transmit the encoded audio signal via a network.

15. The mobile phone of claim 14, wherein the T45 is one point five (1.5).

16. The mobile phone of claim 14, wherein a range of frequency bins of the subband x is one (1) kilohertz (kHz) to two point six (2.6) kHz, and wherein a range of frequency bins of the subband y is four point eight (4.8) kHz to six point four (6.4) kHz.

17. An audio signal encoding method, comprising:

obtaining, by a mobile phone, an analog audio signal;

converting, by the mobile phone, the analog audio signal into a digital audio signal in time domain;

transforming, by the mobile phone, the digital audio signal in time domain to an audio signal in frequency domain, wherein the audio signal in frequency domain comprises a current frame, and the current frame comprises a plurality of subbands;

obtaining, by the mobile phone, reference parameters of the plurality of subbands;

encoding, by the mobile phone and using a high quality transform coding (HQ) algorithm, the current frame to obtain an encoded audio signal when the reference parameters meet a preset parameter condition; and

transmitting, by the mobile phone, the encoded audio signal via a network;

wherein;

the current frame comprises a subband x and a subband y;

wherein the reference parameters comprise a spectral peak of the subband x, a spectral average of the subband x, a spectral peak of the subband y, and a spectral average of the subband y;

wherein the preset parameter condition comprises;

a product of the spectral peak of the subband x multiplied by the spectral average of the subband y is less than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x multiplied by a first constant (T44), and the spectral peak of the subband y is greater than a product of the spectral average of the subband y multiplied by a second constant (T45);

or

the product of the spectral peak of the subband x multiplied by the spectral average of the subband y is greater than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x multiplied by a third constant (T46), and the spectral peak of the subband y is less than a product of the spectral average of the subband y multiplied by the T45.

18. An audio signal encoder, comprising:

at least one microphone, configured to obtain an analog audio signal;

an analog-digital convertor coupled to the at least one microphone, configured to convert the analog audio signal into a digital audio signal in time domain;

a memory storing program instructions; and

at least one processor coupled to the memory, wherein the program instructions cause the at least one processor to be configured to;

transform the digital audio signal in time domain to an audio signal in frequency domain, wherein the audio signal in frequency domain comprises a current frame, and the current frame comprises a plurality of subbands;

obtain reference parameters of the plurality of subbands; and

encode, using a high quality transform coding (HQ) algorithm, the current frame to obtain an encoded audio signal when the reference parameters meet a preset parameter condition; and

a network interface, configured to transmit the encoded audio signal via a network;

wherein the current frame comprises a subband x and a subband y;

wherein the reference parameters comprise a spectral peak of the subband x, a spectral average of the subband x, a spectral peak of the subband y, and a spectral average of the subband y;

wherein the preset parameter condition comprises;

a product of the spectral peak of the subband x multiplied by the spectral average of the subband y is less than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x multiplied by a first constant (T44), and the spectral peak of the subband y is greater than a product of the spectral average of the subband y multiplied by a second constant (T45);

or

the product of the spectral peak of the subband x multiplied by the spectral average of the subband y is greater than a product of the spectral peak of the subband y multiplied by the spectral average of the subband x multiplied by a third constant (T46), and the spectral peak of the subband y is less than a product of the spectral average of the subband y multiplied by the T45.