Method, Apparatus, and System for Processing Audio Data

• US 20140316774A1
• Filed: 06/30/2014
• Published: 10/23/2014
• Est. Priority Date: 12/30/2011
• 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: Wang, Zhe
• Granted Patent: US 9,406,304 B2
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10L 19/012 Comfort noise or silence coding
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes
• CPC Class Codes: G10L 19/22 Mode decision, i.e. based on audio signal content versus external parameters
• CPC Class Codes: G10L 19/265 Pre-filtering, e.g. high frequency emphasis prior to encoding
• CPC Class Codes: G10L 25/21 the extracted parameters being power information
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10

Abstract

A method, an apparatus, and a system for processing audio data are provided that pertain to the field of communications technologies. The method includes: obtaining a noise frame of an audio signal, and decomposing the current noise frame into a noise low-band signal and a noise high-band signal; and encoding and transmitting the noise low-band signal by using a first discontinuous transmission mechanism, and encoding and transmitting the noise high-band signal by using a second discontinuous transmission mechanism. According to the present invention, different processing manners are used for the high-band signal and the low-band signal, calculation loads and encoded bits may be saved under a premise of not lowering subjective quality of a codec, and bits that are saved may help to achieve an objective of reducing a transmission bandwidth or improving overall encoding quality.

Claims

1. A method for processing audio data, comprising:

obtaining a noise frame of an audio signal;

decomposing the noise frame into a noise low-band signal and a noise high-band signal;

encoding the noise low-band signal by using a first discontinuous transmission mechanism and transmitting the encoded noise low-band signal by using a first discontinuous transmission mechanism; and

encoding the noise high-band signal by using a second discontinuous transmission mechanism and transmitting the encoded noise high-band signal by using a second discontinuous transmission mechanism, wherein a policy for sending a first silence insertion descriptor frame (SID) of the first discontinuous transmission mechanism is different from a policy for sending a second SID of the second discontinuous transmission mechanism, or a policy for encoding a first SID of the first discontinuous transmission mechanism is different from a policy for encoding a second SID of the second discontinuous transmission mechanism.

2. The method according to claim 1, wherein the first SID comprises a low-band parameter of the noise frame, and the second SID comprises a low-band parameter or a high-band parameter of the noise frame.

3. The method according to claim 1, wherein encoding the noise high-band signal by using the second discontinuous transmission mechanism and transmitting the encoded noise high-band signal by using the second discontinuous transmission mechanism comprises:

determining whether the noise high-band signal has a preset spectral structure;

encoding a SID of the noise high-band signal by using the policy for encoding the second SID and sending the SID when the noise high-band signal has the preset spectral structure and a sending condition of the policy for sending the second SID is satisfied; and

determining that the noise high-band signal does not need to be encoded and transmitted when the noise high-band signal does not have the preset spectral structure.

4. The method according to claim 3, wherein determining whether the noise high-band signal has the preset spectral structure comprises:

obtaining a spectrum of the noise high-band signal;

dividing the spectrum into at least two sub-bands;

determining that the noise high-band signal has no preset spectral structure when an average energy of any first sub-band in the sub-bands is not smaller than an average energy of a second sub-band in the sub-bands, wherein a frequency band in which the second sub-band is located is higher than a frequency band in which the first sub-band is located; and

determining that the noise high-band signal has a preset spectral structure when the average energy of any first sub-band in the sub-bands is smaller than the average energy of the second sub-band in the sub-bands.

5. The method according to claim 1, wherein encoding the noise high-band signal by using the second discontinuous transmission mechanism and transmitting the encoded noise high-band signal by using the second discontinuous transmission mechanism comprises:

generating a deviation according to a first ratio and a second ratio, wherein the first ratio is a ratio of an energy of the noise high-band signal to an energy of the noise low-band signal of the noise frame, and the second ratio is a ratio of an energy of a noise high-band signal to an energy of a noise low-band signal at a moment when a SID comprising a noise high-band parameter is sent last time before the noise frame;

determining whether the deviation reaches a preset threshold;

encoding a SID of the noise high-band signal by using the policy for encoding the second SID and sending the SID when the deviation reaches the preset threshold; and

determining that the noise high-band signal does not need to be encoded and transmitted when the deviation does not reach the preset threshold.

6. The method according to claim 5, wherein the first ratio is the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal of the noise frame comprises the first ratio being a ratio of an instant energy of the noise high-band signal to an instant energy of the noise low-band signal of the noise frame, wherein the second ratio is the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal at the moment when the SID comprising the noise high-band parameter is sent last time before the noise frame comprises the second ratio being a ratio of an instant energy of the noise high-band signal to an instant energy of the noise low-band signal at the moment when the SID comprising the noise high-band parameter is sent last time before the noise frame, or wherein the first ratio is the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal of the noise frame comprises the first ratio being a ratio of a weighted average energy of noise high-band signals of the noise frame and a noise frame prior to the noise frame to a weighted average energy of noise low-band signals of the noise frame and the noise frame prior to the noise frame, and wherein the second ratio is the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal at the moment when the SID comprising the noise high-band parameter is sent last time before the noise frame comprises the second ratio being a ratio of a weighted average energy of high-band signals to a weighted average energy of low-band signals of a noise frame and a noise frame prior to the noise frame at the moment when the SID comprising the noise high-band parameter is sent last time before the noise frame.

7. The method according to claim 5, wherein generating the deviation according to the first ratio and the second ratio comprises:

separately calculating a logarithmic value of the first ratio and a logarithmic value of the second ratio; and

calculating an absolute value of a difference between the logarithmic value of the first ratio and the logarithmic value of the second ratio to obtain the deviation.

8. The method according to claim 1, wherein encoding the noise high-band signal by using the second discontinuous transmission mechanism and transmitting the noise high-band signal by using the second discontinuous transmission mechanism comprises:

determining whether a spectral structure of the noise high-band signal of the noise frame, in comparison with an average spectral structure of noise high-band signals before the noise frame, satisfies a preset condition;

encoding a SID of the noise high-band signal of the noise frame by using the policy for encoding the second SID and sending the SID when the spectral structure of the noise high-band signal of the noise frame satisfies the preset condition; and

determining that the noise high-band signal of the noise frame does not need to be encoded and transmitted when the spectral structure of the noise high-band signal of the noise frame does not satisfy the preset condition.

9. The method according to claim 8, wherein the average spectral structure of the noise high-band signals before the noise frame comprises a weighted average of spectrums of the noise high-band signals before the noise frame.

10. The method according to a claim 3, wherein the sending condition in the policy for sending the second SID of the second discontinuous transmission mechanism further comprises the first discontinuous transmission mechanism satisfying a condition for sending the first SID.

11. A method for processing audio data, comprising:

obtaining, by a decoder, a silence insertion descriptor frame (SID);

determining whether the SID comprises a low-band parameter or a high-band parameter;

decoding the SID to obtain a noise low-band parameter, locally generating a noise high-band parameter, and obtaining a first comfort noise (CN) frame according to the noise low-band parameter obtained by decoding and the locally generated noise high-band parameter when the SID comprises the low-band parameter;

decoding the SID to obtain a noise high-band parameter, locally generating a noise low-band parameter, and obtaining a second CN frame according to the noise high-band parameter obtained by decoding and the locally generated noise low-band parameter when the SID comprises the high-band parameter; and

decoding the SID to obtain a noise high-band parameter and a noise low-band parameter, and obtaining a third CN frame according to the noise high-band parameter and the noise low-band parameter obtained by decoding when the SID comprises the high-band parameter and the low-band parameter.

12. The method according to claim 11, wherein the SID comprises the low-band parameter, and before decoding the SID to obtain the noise low-band parameter, locally generating the noise high-band parameter, and obtaining the first CN frame according to the noise low-band parameter obtained by decoding and the locally generated noise high-band parameter, the method further comprises entering, by the decoder, a second comfort noise generation (CNG) state when the decoder is in a first CNG state.

13. The method according to claim 11, wherein the SID comprises the high-band parameter and the low-band parameter, and before decoding the SID to obtain the noise high-band parameter and the noise low-band parameter, and obtaining the third CN frame according to the noise high-band parameter and the noise low-band parameter obtained by decoding, the method further comprises entering, by the decoder, a first comfort noise generation (CNG) state when the decoder is in a second CNG state.

14. The method according to claim 11, wherein determining whether the SID comprises the low-band parameter and/or the high-band parameter comprises:

determining that the SID comprises the high-band parameter when the number of bits of the SID is smaller than a preset first threshold;

determining that the SID comprises the low-band parameter when the number of bits of the SID is greater than a preset first threshold and smaller than a preset second threshold; and

determining that the SID comprises the high-band parameter and the low-band parameter when the number of bits of the SID is greater than a preset second threshold and smaller than a preset third threshold;

or

determining that the SID comprises the high-band parameter when the SID comprises a first identifier;

determining that the SID comprises the low-band parameter when the SID comprises a second identifier; and

determining that the SID comprises the low-band parameter and the high-band parameter when the SID comprises a third identifier.

15. The method according to claim 11, wherein locally generating the noise high-band parameter comprises:

separately obtaining a weighted average energy of a noise high-band signal and a synthesis filter coefficient of the noise high-band signal at a moment corresponding to the SID; and

obtaining the noise high-band signal according to the obtained weighted average energy of the noise high-band signal and the obtained synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID.

16. The method according to claim 15, wherein obtaining the weighted average energy of the noise high-band signal at the moment corresponding to the SID comprises:

obtaining an energy of a low-band signal of the first CN frame according to the noise low-band parameter obtained by decoding;

calculating a ratio of an energy of a noise high-band signal to an energy of a noise low-band signal at a moment when a SID comprising a high-band parameter is received before the SID to obtain a first ratio;

obtaining, according to the energy of the low-band signal of the first CN frame and the first ratio, an energy of the noise high-band signal at the moment corresponding to the SID; and

performing weighted averaging on the energy of the noise high-band signal at the moment corresponding to the SID and an energy of a high-band signal of a locally buffered CN frame to obtain the weighted average energy of the noise high-band signal at the moment corresponding to the SID, wherein the weighted average energy of the noise high-band signal at the moment corresponding to the SID is a high-band signal energy of the first CN frame.

17. The method according to claim 16, wherein calculating the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal at the moment when the SID comprising the high-band parameter is received before the SID to obtain the first ratio, comprises:

calculating a ratio of an instant energy of the noise high-band signal to an instant energy of the noise low-band signal at the moment when the SID comprising the high-band parameter is received before the SID to obtain the first ratio;

or

calculating a ratio of a weighted average energy of the noise high-band signal to a weighted average energy of the noise low-band signal at the moment when the SID comprising the high-band parameter is received before the SID to obtain the first ratio.

18. The method according to claim 16, wherein the energy of the high-band signal of the previous CN frame that is locally buffered is updated at a first rate when the energy of the noise high-band signal at the moment corresponding to the SID is greater than an energy of a high-band signal of a previous CN frame that is locally buffered, wherein the energy of the high-band signal of the previous CN frame that is locally buffered is updated at a second rate when the energy of the noise high-band signal at the moment corresponding to the SID is not greater than the energy of the high-band signal of the previous CN frame that is locally buffered, and wherein the first rate is greater than the second rate.

19. The method according to claim 15, wherein obtaining the weighted average energy of the noise high-band signal at the moment corresponding to the SID comprises:

selecting a high-band signal of a speech frame with a minimum high-band signal energy from speech frames within a preset period of time before the SID; and

obtaining, according to an energy of the high-band signal of the speech frame with the minimum high-band signal energy among the speech frames, the weighted average energy of the noise high-band signal at the moment corresponding to the SID, wherein the weighted average energy of the noise high-band signal at the moment corresponding to the SID is a high-band signal energy of the first CN frame;

or

selecting high-band signals of N speech frames with a high-band signal energy smaller than a preset threshold from speech frames within a preset period of time before the SID; and

obtaining, according to a weighted average energy of the high-band signals of the N speech frames, the weighted average energy of the noise high-band signal at the moment corresponding to the SID, wherein the weighted average energy of the noise high-band signal at the moment corresponding to the SID is a high-band signal energy of the first CN frame.

20. The method according to claim 15, wherein obtaining the synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID comprises:

distributing M immittance spectral frequency (ISF) coefficients, immittance spectral pair (ISP) coefficients, line spectral frequency (LSF) coefficients, or line spectral pair (LSP) coefficients in a frequency range corresponding to a high-band signal;

performing randomization processing on the M coefficients, wherein a feature of the randomization comprises causing each coefficient among the M coefficients to gradually approach a target value corresponding to each coefficient, wherein the target value is a value in a preset range adjacent to a coefficient value, and the target value of each coefficient among the M coefficients changes after every N frames, wherein both the M and the N are natural numbers; and

obtaining, according to the filter coefficients obtained by randomization processing, the synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID.

21. The method according to claim 15, wherein obtaining the synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID comprises:

obtaining M immittance spectral frequency (ISF) coefficients, immittance spectral pair (ISP) coefficients, line spectral frequency (LSF) coefficients, or line spectral pair (LSP) coefficients of a locally buffered noise high-band signal;

performing randomization processing on the M coefficients, wherein a feature of the randomization comprises causing each coefficient among the M coefficients to gradually approach a target value corresponding to each coefficient, wherein the target value is a value in a preset range adjacent to a coefficient value, and the target value of each coefficient among the M coefficients changes after every N frames; and

obtaining, according to the filter coefficients obtained by randomization processing, the synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID.

22. The method according to claim 15, wherein before obtaining the first CN frame according to the noise low-band parameter obtained by decoding and the locally generated noise high-band parameter, the method further comprises:

multiplying noise high-band signals of subsequent L frames starting from the SID by a smoothing factor smaller than 1 to obtain a new weighted average energy of the locally generated noise high-band signals when history frames adjacent to the SID are encoded speech frames and when an average energy of high-band signals or a part of high-band signals that are decoded from the encoded speech frames is smaller than an average energy of noise high-band signals or a part of the noise high-band signals that are generated locally, and

wherein obtaining the first CN frame according to the noise low-band parameter obtained by decoding and the locally generated noise high-band parameter comprises obtaining a fourth CN frame according to the noise low-band parameter obtained by decoding, the synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID, and the new weighted average energy of the locally generated noise high-band signals.

23. An apparatus for encoding audio data, comprising:

an obtaining module configured to obtain a noise frame of an audio signal, and decompose the noise frame into a noise low-band signal and a noise high-band signal; and

a transmitting module configured to encode the noise low-band signal by using a first discontinuous transmission mechanism and transmit the encoded noise low-band signal by using the first discontinuous transmission mechanism, and encode the noise high-band signal by using a second discontinuous transmission mechanism and transmit the encoded noise high-band signal by using the second discontinuous transmission mechanism, wherein a policy for sending a first silence insertion descriptor frame (SID) of the first discontinuous transmission mechanism is different from a policy for sending a second SID of the second discontinuous transmission mechanism, or a policy for encoding a first SID of the first discontinuous transmission mechanism is different from a policy for encoding a second SID of the second discontinuous transmission mechanism.

24. The apparatus according to claim 23, wherein the first SID comprises a low-band parameter of the noise frame, and the second SID comprises a low-band parameter or a high-band parameter of the noise frame.

25. The apparatus according to claim 23, wherein the transmitting module comprises a first transmitting unit configured to:

determine whether the noise high-band signal has a preset spectral structure;

encode a SID of the noise high-band signal by using the policy for encoding the second SID and send the SID when the noise high-band signal has the preset spectral structure and a sending condition of the policy for sending the second SID is satisfied; and

determine that the noise high-band signal does not need to be encoded and transmitted when the noise high-band signal does not have the preset spectral structure and the sending condition of the policy for sending the second SID is not satisfied.

26. The apparatus according to claim 25, wherein the first transmitting unit comprises a first determining subunit configured to:

obtain a spectrum of the noise high-band signal;

divide the spectrum into at least two sub-bands;

determine that the noise high-band signal has no preset spectral structure when an average energy of any first sub-band in the sub-bands is not smaller than an average energy of a second sub-band in the sub-bands, wherein a frequency band in which the second sub-band is located is higher than a frequency band in which the first sub-band is located; and

determine that the noise high-band signal has a preset spectral structure when the average energy of any first sub-band in the sub-bands is smaller than the average energy of the second sub-band in the sub-bands.

27. The apparatus according to claim 23, wherein the transmitting module comprises a second transmitting unit configured to:

generate a deviation according to a first ratio and a second ratio, wherein the first ratio is a ratio of an energy of the noise high-band signal to an energy of the noise low-band signal of the noise frame, and the second ratio is a ratio of an energy of a noise high-band signal to an energy of a noise low-band signal at a moment when a SID comprising a noise high-band parameter is sent last time before the noise frame;

determine whether the deviation reaches a preset threshold;

encode a SID of the noise high-band signal by using the policy for encoding the second SID and send an encoded SID when the deviation reaches the preset threshold; and

determine that the noise high-band signal does not need to be encoded and transmitted when the deviation does not reach the preset threshold.

28. The apparatus according to claim 27, wherein the first ratio is the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal of the noise frame comprises the first ratio being a ratio of an instant energy of the noise high-band signal to an instant energy of the noise low-band signal of the noise frame, wherein the second ratio is the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal at the moment when the SID comprising the noise high-band parameter is sent last time before the noise frame comprises the second ratio being a ratio of an instant energy of the noise high-band signal to an instant energy of the noise low-band signal at the moment when the SID comprising the noise high-band parameter is sent last time before the noise frame, or wherein the first ratio is the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal of the noise frame comprises the first ratio being a ratio of a weighted average energy of noise high-band signals of the noise frame and a noise frame prior to the noise frame to a weighted average energy of noise low-band signals of the noise frame and the noise frame prior to the noise frame, and wherein the second ratio is the ratio of the energy of the noise high-band signal to the energy of the noise low-band signal at the moment when the SID comprising the noise high-band parameter is sent last time before the noise frame comprises the second ratio being a ratio of a weighted average energy of high-band signals to a weighted average energy of low-band signals of a noise frame and a noise frame prior to the noise frame at the moment when the SID comprising the noise high-band parameter is sent last time before the noise frame.

29. The apparatus according to claim 27, wherein the second transmitting unit comprises a calculating subunit configured to:

separately calculate a logarithmic value of the first ratio and a logarithmic value of the second ratio; and

calculate an absolute value of a difference between the logarithmic value of the first ratio and the logarithmic value of the second ratio to obtain the deviation.

30. The apparatus according to claim 23, wherein the first transmitting module comprises a third transmitting unit configured to:

determine whether a spectral structure of the noise high-band signal of the noise frame, in comparison with an average spectral structure of noise high-band signals before the noise frame, satisfies a preset condition;

encode a SID of the noise high-band signal of the noise frame by using the policy for encoding the second SID and send an encoded SID when the spectral structure of the noise high-band signal of the noise frame satisfies the present condition; and

determine that the noise high-band signal of the noise frame does not need to be encoded and transmitted when the spectral structure of the noise high-band signal of the noise frame does not satisfy the preset condition.

31. The apparatus according to claim 30, wherein the average spectral structure of the noise high-band signals before the noise frame comprises a weighted average of spectrums of the noise high-band signals before the noise frame.

32. The apparatus according to claim 25, wherein the sending condition in the policy for sending the second SID of the second discontinuous transmission mechanism further comprises the first discontinuous transmission mechanism satisfying a condition for sending the first SID.

33. An apparatus for decoding audio data, comprising:

an obtaining module configured to obtain a silence insertion descriptor frame (SID), and determine whether the SID comprises a low-band parameter or a high-band parameter;

a first decoding module configured to decode the SID to obtain a noise low-band parameter, locally generate a noise high-band parameter, and obtain a first comfort noise (CN) frame according to the noise low-band parameter obtained by decoding and the locally generated noise high-band parameter when the SID obtained by the obtaining module comprises the low-band parameter;

a second decoding module configured to decode the SID to obtain a noise high-band parameter, locally generate a noise low-band parameter, and obtain a second CN frame according to the noise high-band parameter obtained by decoding and the locally generated noise low-band parameter when the SID obtained by the obtaining module comprises the high-band parameter; and

a third decoding module configured to decode the SID to obtain a noise high-band parameter and a noise low-band parameter, and obtain a third CN frame according to the noise high-band parameter and the noise low-band parameter obtained by decoding when the SID obtained by the obtaining module comprises the high-band parameter and the low-band parameter.

34. The apparatus according to claim 33, wherein the first decoding module is further configured to, before decoding the SID to obtain a noise low-band parameter, locally generating a noise high-band parameter, and obtaining a first CN frame according to the noise low-band parameter obtained by decoding and the locally generated noise high-band parameter, when the apparatus is in a first comfort noise generation (CNG) state, enter a second CNG state.

35. The apparatus according to claim 33, wherein the third decoding module is further configured to, before decoding the SID to obtain a noise high-band parameter and a noise low-band parameter, and obtaining a third CN frame according to the noise high-band parameter and the noise low-band parameter obtained by decoding, when the apparatus is in a second comfort noise generation (CNG) state, enter a first CNG state.

36. The apparatus according to claim 33, wherein the obtaining module comprises:

a first determining unit configured to;

determine that the SID comprises the high-band parameter when the number of bits of the SID is smaller than a preset first threshold;

determine that the SID comprises the low-band parameter when the number of bits of the SID is greater than a preset first threshold and smaller than a preset second threshold; and

determine that the SID comprises the high-band parameter and the low-band parameter when the number of bits of the SID is greater than a preset second threshold and smaller than a preset third threshold;

or

a second determining unit configured to;

determine that the SID comprises the high-band parameter when the SID comprises a first identifier;

determine that the SID comprises the low-band parameter when the SID comprises a second identifier; and

determine that the SID comprises the low-band parameter and the high-band parameter when the SID comprises a third identifier.

37. The apparatus according to claim 33, wherein the first decoding module comprises:

a first obtaining unit configured to separately obtain a weighted average energy of a noise high-band signal and a synthesis filter coefficient of the noise high-band signal at a moment corresponding to the SID; and

a second obtaining unit configured to obtain the noise high-band signal according to the obtained weighted average energy of the noise high-band signal and the obtained synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID.

38. The apparatus according to claim 37, wherein the first obtaining unit comprises:

a first obtaining subunit configured to obtain an energy of a low-band signal of the first CN frame according to the noise low-band parameter obtained by decoding;

a calculating subunit configured to calculate a ratio of an energy of a noise high-band signal to an energy of a noise low-band signal at a moment when a SID comprising a high-band parameter is received before the SID to obtain a first ratio;

a second obtaining subunit configured to obtain, according to the energy of the low-band signal of the first CN frame and the first ratio, an energy of the noise high-band signal at the moment corresponding to the SID; and

a third obtaining subunit configured to perform weighted averaging on the energy of the noise high-band signal at the moment corresponding to the SID and an energy of a high-band signal of a locally buffered CN frame to obtain the weighted average energy of the noise high-band signal at the moment corresponding to the SID, wherein the weighted average energy of the noise high-band signal at the moment corresponding to the SID is a high-band signal energy of the first CN frame.

39. The apparatus according to claim 38, wherein the calculating subunit is specifically configured to:

calculate a ratio of an instant energy of the noise high-band signal to an instant energy of the noise low-band signal at the moment when the SID comprising the high-band parameter is received before the SID to obtain the first ratio;

or

calculate a ratio of a weighted average energy of the noise high-band signal to a weighted average energy of the noise low-band signal at the moment when the SID comprising the high-band parameter is received before the SID to obtain the first ratio.

40. The apparatus according to claim 38, wherein the energy of the high-band signal of the previous CN frame that is locally buffered is updated at a first rate when the energy of the noise high-band signal at the moment corresponding to the SID is greater than an energy of a high-band signal of a previous CN frame that is locally buffered, or wherein the energy of the high-band signal of the previous CN frame that is locally buffered is updated at a second rate when the energy of the noise high-band signal at the moment corresponding to the SID is not greater than an energy of a high-band signal of a previous CN frame that is locally buffered, wherein the first rate is greater than the second rate.

41. The apparatus according to claim 37, wherein the first obtaining unit comprises:

a first selecting subunit configured to select a high-band signal of a speech frame with a minimum high-band signal energy from speech frames within a preset period of time before the SID, and obtain, according to an energy of the high-band signal of the speech frame with the minimum high-band signal energy among the speech frames, the weighted average energy of the noise high-band signal at the moment corresponding to the SID, wherein the weighted average energy of the noise high-band signal at the moment corresponding to the SID is a high-band signal energy of the first CN frame;

or

a second selecting subunit configured to select high-band signals of N speech frames with a high-band signal energy smaller than a preset threshold from speech frames within a preset period of time before the SID, and obtain, according to a weighted average energy of the high-band signals of the N speech frames, the weighted average energy of the noise high-band signal at the moment corresponding to the SID, wherein the weighted average energy of the noise high-band signal at the moment corresponding to the SID is a high-band signal energy of the first CN frame.

42. The apparatus according to claim 37, wherein the first obtaining unit comprises:

a distributing subunit configured to distribute M immittance spectral frequency (ISF) coefficients, immittance spectral pair (ISP) coefficients, line spectral frequency (LSF) coefficients, or line spectral pair (LSP) coefficients in a frequency range corresponding to a high-band signal;

a first randomization processing subunit configured to perform randomization processing on the M coefficients, wherein a feature of the randomization comprises causing each coefficient among the M coefficients to gradually approach a target value corresponding to each coefficient, wherein the target value is a value in a preset range adjacent to a coefficient value, and the target value of each coefficient among the M coefficients changes after every N frames, wherein both the M and the N are natural numbers; and

a fourth obtaining subunit configured to obtain, according to the filter coefficients obtained by randomization processing, the synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID.

43. The apparatus according to claim 37, wherein the first obtaining unit comprises:

a fifth obtaining subunit configured to obtain M immittance spectral frequency (ISF) coefficients, immittance spectral pair (ISP) coefficients, line spectral frequency (LSF) coefficients, or line spectral pair (LSP) coefficients of a locally buffered noise high-band signal;

a second randomization processing subunit configured to perform randomization processing on the M coefficients, wherein a feature of the randomization comprises causing each coefficient among the M coefficients to gradually approach a target value corresponding to each coefficient, wherein the target value is a value in a preset range adjacent to a coefficient value, and the target value of each coefficient among the M coefficients changes after every N frames; and

a sixth obtaining subunit configured to obtain, according to the filter coefficients obtained by randomization processing, the synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID.

44. The apparatus according to claim 37, wherein the apparatus further comprises a an optimizing module configured to, before the first decoding module obtains the first CN frame, when history frames adjacent to the SID are encoded speech frames, when an average energy of high-band signals or a part of high-band signals that are decoded from the encoded speech frames is smaller than an average energy of noise high-band signals or a part of the noise high-band signals that are generated locally, multiply noise high-band signals of subsequent L frames starting from the SID by a smoothing factor smaller than 1, to obtain a new weighted average energy of the locally generated noise high-band signals, and wherein the first decoding module is specifically configured to obtain a fourth CN frame according to the noise low-band parameter obtained by decoding, the synthesis filter coefficient of the noise high-band signal at the moment corresponding to the SID, and the new weighted average energy of the locally generated noise high-band signals.