Adaptive Audio Signal Coding

• US 20140114670A1
• Filed: 12/31/2013
• Published: 04/24/2014
• Est. Priority Date: 10/08/2011
• 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: MIAO, Lei, LIU, Zexin
• Granted Patent: US 9,251,798 B2
• Time in Patent Office: Days
• US Class Current: 704/500
• CPC Class Codes: G10L 19/008 Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/087 using mixed excitation models, e.g. MELP, MBE, split band LPC or HVXC
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes
• CPC Class Codes: G10L 19/265 Pre-filtering, e.g. high frequency emphasis prior to encoding
• CPC Class Codes: G10L 21/038 using band spreading techniques
• CPC Class Codes: G10L 25/18 the extracted parameters being spectral information of each sub-band

Abstract

Example embodiments described herein generally provide for adaptive audio signal coding of low-frequency and high-frequency audio signals. More specifically, audio signals are categorized into high-frequency audio signals and low-frequency audio signals. Then, based on a set coding and/or characteristics of the low-frequency audio signals, the low-frequency coding manner is selected. Similarly, but in addition to, a bandwidth extension mode to code the high-frequency audio signals is selected according to the low-frequency coding manner and/or characteristics of the audio signals.

Claims

1. In an audio encoder, a method of adaptive audio signal coding, the method comprising:

categorizing audio signals into high-frequency audio signals and low-frequency audio signals;

coding the low-frequency audio signals by using a time domain coding manner or a frequency domain coding manner according to characteristics of the low-frequency audio signals; and

selecting a bandwidth extension mode to code the high-frequency audio signals according to a low-frequency coding manner, characteristics of the audio signals, or both.

2. The adaptive audio signal coding method according to claim 1, wherein the selecting the bandwidth extension mode to code the high-frequency audio signals according to the low-frequency coding further comprises:

determining that the low-frequency audio signals should be coded by using the time domain coding manner, and selecting a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals;

or

otherwise, determining that the low-frequency audio signals should be coded by using the frequency domain coding manner, and selecting a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals.

3. The adaptive audio signal coding method according to claim 1, wherein the selecting the bandwidth extension mode to code the high-frequency audio signals according to the characteristics of the audio signals further comprises:

determining that the audio signals are voice signals, and selecting a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals;

or

otherwise, determining that the audio signals are music signals, and selecting a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals.

4. The adaptive audio signal coding method according to claim 3, wherein the selecting the bandwidth extension mode to code the high-frequency audio signals according to the low-frequency coding manner and the characteristics of the audio signals further comprises:

determining that the low-frequency audio signals should be coded by using the time domain coding manner and the audio signals are voice signals;

thus, selecting a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals;

or

otherwise, selecting a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals.

5. The adaptive audio signal coding apparatus according to claim 1, further comprising:

performing delay processing on the high-frequency audio signals or the low-frequency audio signals, so that delay of the high-frequency audio signals and delay of the low-frequency audio signals are the same at a decoding end.

6. The adaptive audio signal coding method according to claim 1, wherein the coding the high-frequency audio signals further comprises:

coding the high-frequency audio signals after performing first delay for the high-frequency audio signals, so that coding delay and decoding delay of the audio signals are a sum of the first delay and second delay;

wherein the first delay is delay generated during coding and decoding of the low-frequency audio signals, and the second delay is delay generated during coding of the high-frequency audio signals.

7. The adaptive audio signal coding method according to claim 6, wherein when first delay is smaller or equal to than second delay, the low-frequency audio signals are delayed by a difference between the second delay and the first delay after being coded, so that coding delay and decoding delay of the audio signals are the second delay;

when first delay is larger than second delay, the high-frequency audio signals are delayed by a difference between the first delay and the second delay after being coded, so that coding delay and decoding delay of the audio signals are the first delay;

wherein the first delay is delay generated during coding and decoding of the low-frequency audio signals, and the second delay is delay generated during coding of the high-frequency audio signals.

8. The adaptive audio signal coding method according to claim 7, wherein the coding the high-frequency audio signals further comprises:

coding the high-frequency audio signals after performing third delay for the high-frequency audio signals;

when first delay is smaller than or equal to second delay, the low-frequency audio signals are delayed by a difference between a sum of the second delay and the third delay, and the first delay after being coded, so that coding delay and decoding delay of the audio signals are the sum of the second delay and the third delay;

when first delay is larger than second delay, the high-frequency audio signals are delayed by a difference between the first delay and a sum of the second delay and the third delay after being coded, or the low-frequency audio signals are delayed by a difference between a sum of the second delay and the third delay, and the first delay, so that coding delay and decoding delay of the audio signals are the first delay or the sum of the second delay and the third delay.

9. An adaptive audio signal coding apparatus, comprising:

a categorizing unit, configured to categorize audio signals into high-frequency audio signals and low-frequency audio signals;

a low-frequency signal coding unit, configured to code the low-frequency audio signals by using a time domain coding manner or a frequency domain coding manner according to characteristics of the low-frequency audio signals; and

a high-frequency signal coding unit, configured to select a bandwidth extension mode to code the high-frequency audio signals according to a low-frequency coding manner, characteristics of the audio signals, or both.

10. The adaptive audio signal coding apparatus according to claim 9, wherein the high-frequency signal coding unit is further configured to:

select a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals if the low-frequency audio signals should be coded by using the time domain coding manner;

or

select a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals if the low-frequency audio signals should be coded by using the frequency domain coding manner.

11. The adaptive audio signal coding apparatus according to claim 9, wherein if the audio signals are voice signals, the high-frequency signal coding unit is further configured to:

select a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals;

or

otherwise, if the audio signals are music signals, the high-frequency signal coding unit is further configured to;

select a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals.

12. The adaptive audio signal coding apparatus according to claim 9, wherein the high-frequency signal coding unit is further configured to:

select a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals if the low-frequency audio signals should be coded by using the time domain coding manner and the audio signals are voice signals;

otherwise, select a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals.

13. The adaptive audio signal coding apparatus according to claim 9, further comprising:

a low-frequency signal decoding unit, configured to decode the low-frequency audio signals;

wherein first delay is generated during the coding and decoding of the low-frequency audio signals; and

wherein the high-frequency signal coding unit is specifically configured to after delaying the high-frequency audio signals by the first delay, code the delayed high-frequency audio signals, so that coding delay and decoding delay of the audio signals are a sum of the first delay and second delay, wherein the second delay is generated during the coding of the high-frequency audio signals.

14. The adaptive audio signal coding apparatus according to claim 13, wherein:

when first delay is smaller than or equal to second delay, the low-frequency signal coding unit is configured to after coding the low-frequency audio signals, delay the coded low-frequency audio signals by a difference between the second delay and the first delay, so that coding delay and decoding delay of the audio signals are the second delay;

when first delay is larger than second delay, the high-frequency signal coding unit is configured to after coding the high-frequency audio signals, delay the coded high-frequency signals by a difference between the first delay and the second delay, so that coding delay and decoding delay of the audio signals are the first delay;

wherein the first delay is delay generated during coding and decoding of the low-frequency audio signals, and the second delay is delay generated during coding of the high-frequency audio signals.

15. The adaptive audio signal coding apparatus according to claim 13, wherein:

the high-frequency signal coding unit is specifically configured to code the high-frequency audio signals after performing third delay for the high-frequency audio signals; and

when first delay is smaller than or equal to second delay, the low-frequency signal coding unit is configured to after coding the low-frequency audio signals, delay the coded low-frequency audio signals by a difference between a sum of the second delay and the third delay, and the first delay, so that coding delay and decoding delay of the audio signals are the sum of the second delay and the third delay;

when first delay is larger than second delay, the high-frequency signal coding unit is configured to after coding the high-frequency audio signals, delay the coded high-frequency audio signals by a difference between the first delay and a sum of the second delay and the third delay, or the low-frequency signal coding unit after coding the low-frequency audio signals, delays the coded low-frequency audio signals by a difference between a sum of the second delay and the third delay, and the first delay after coding the low-frequency audio signals, so that coding delay and decoding delay of the audio signals are the first delay or the sum of the second delay and the third delay;

wherein the first delay is delay generated during coding and decoding of the low-frequency audio signals, and the second delay is delay generated during coding of the high-frequency audio signals.

16. A computer program product comprising computer executable instructions stored on a non-transitory computer readable medium such that when executed by a computer program processor cause adaptive audio signal coding that:

categorize audio signals into high-frequency audio signals and low-frequency audio signals;

code the low-frequency audio signals by using a time domain coding manner or a frequency domain coding manner according to characteristics of the low-frequency audio signals; and

select a bandwidth extension mode to code the high-frequency audio signals according to a low-frequency coding manner, characteristics of the audio signals, or both.

17. The computer program product according to claim 16, wherein the computer executable instructions that select the bandwidth extension mode to code the high-frequency audio signals according to the low-frequency coding further comprise instruction that:

determine that the low-frequency audio signals should be coded by using the time domain coding manner, and select a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals;

or

otherwise, determine that the low-frequency audio signals should be coded by using the frequency domain coding manner, and select a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals.

18. The computer program product according to claim 16, wherein the computer executable instructions that select the bandwidth extension mode to code the high-frequency audio signals according to the characteristics of the audio signals further comprise instructions that:

determine that the audio signals are voice signals, and selecting a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals;

or

otherwise, determine that the audio signals are music signals, and selecting a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals.

19. The computer program product according to claim 16, wherein the computer executable instructions that select the bandwidth extension mode to code the high-frequency audio signals according to the low-frequency coding manner and the characteristics of the audio signals further comprise computer executable instructions that:

determine that the low-frequency audio signals should be coded by using the time domain coding manner and the audio signals are voice signals; and

thus, select a time domain bandwidth extension mode to perform time domain coding for the high-frequency audio signals;

or

otherwise, select a frequency domain bandwidth extension mode to perform frequency domain coding for the high-frequency audio signals.

20. The computer program product according to claim 16, further comprising computer executable instructions that:

perform delay processing on the high-frequency audio signals or the low-frequency audio signals, so that delay of the high-frequency audio signals and delay of the low-frequency audio signals are the same at a decoding end.