# US 10,121,484 B2 · Method and apparatus for decoding speech/audio bitstream

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- Number: US 10,121,484 B2
- Document ID: US10121484B2
- Status: Granted
- Kind: B2
- Application number: 15/635,690
- Filed: 2017-06-28
- Published: 2017-10-19
- Granted: 2018-11-06
- Earliest claimed: 2013-12-31
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co.,Ltd.
- Inventors: Zexin Liu; Xingtao Zhang; Lei Miao
- Web page: https://patentgrep.com/patent/US10121484B2

## CPC

- G10L 19/167: {Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes}
- G10L 19/005: Correction of errors induced by the transmission channel, if related to the coding algorithm
- G10L 19/06: Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients
- G10L 25/93: Discriminating between voiced and unvoiced parts of speech signals (G10L25/90 takes precedence)
- G10L 2019/0002: {Codebook adaptations}
- G10L 2025/932: {Decision in previous or following frames}
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING

## Abstract

A method and an apparatus for decoding a speech/audio bitstream are disclosed, where the method for decoding a speech/audio bitstream includes determining whether a current frame is a normal decoding frame or a redundancy decoding frame, obtaining a decoded parameter of the current frame by means of parsing when the current frame is a normal decoding frame or a redundancy decoding frame, performing post-processing on the decoded parameter of the current frame to obtain a post-processed decoded parameter of the current frame, and using the post-processed decoded parameter of the current frame to reconstruct a speech/audio signal.

## Claims

### Claim 1

A method for decoding an audio bitstream, comprising:
performing decoding operations on an audio bitstream comprising a first frame and a second frame, wherein a decoded parameter of the first frame and a decoded parameter of the second frame are acquired via the decoding operations, and wherein the second frame is a previous frame of the first frame;
performing, according to the decoded parameter of the first frame and the decoded parameter of the second frame, post-processing on the decoded parameter of the first frame to obtain a post-processed decoded parameter of the first frame when at least one of the first frame or the second frame is a redundancy decoding frame; and
reconstructing an audio signal using the post-processed decoded parameter of the first frame.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the decoded parameter of the first frame comprises a spectral pair parameter of the first frame, the decoded parameter of the second frame comprises a spectral pair parameter of the second frame, and wherein performing post-processing on the decoded parameter of the first frame comprises obtaining a post-processed spectral pair parameter of the first frame using the following formula:
lsp[k]=α*lsp_old[k]+δ*lsp_new[k];
wherein 0≤k≤M, lsp[k] is the post-processed spectral pair parameter of the first frame, lsp_old[k] is the spectral pair parameter of the second frame, lsp_new[k] is the spectral pair parameter of the first frame, M is an order of spectral pair parameters, α is a weight of the spectral pair parameter of the second frame, and δ is a weight of the spectral pair parameter of the first frame, and wherein α≥0, δ≥0, and α+δ=1.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the decoded parameter of the first frame comprises a spectral pair parameter of the first frame, the decoded parameter of the second frame comprises a spectral pair parameter of the second frame, and wherein performing post-processing on the decoded parameter of the first frame comprises obtaining a post-processed spectral pair parameter of the first frame using the following formula:
lsp[k]=α*lsp_old[k]+β*lsp_mid[k]+δ*lsp_new[k];
wherein 0≤k≤M, wherein lsp[k] is the post-processed spectral pair parameter of the first frame, wherein lsp_old[k] is the spectral pair parameter of the second frame, wherein lsp_mid[k] is a middle value of the spectral pair parameter of the first frame, wherein lsp_new[k] is the spectral pair parameter of the first frame, wherein M is an order of spectral pair parameters, wherein α is a weight of the spectral pair parameter of the second frame, wherein β is a weight of the middle value of the spectral pair parameter of the first frame, and wherein δ is a weight of the spectral pair parameter of the first frame.

### Claim 4 (depends on 3)

The method according to claim 3, wherein a value of α, β and δ is determined based on a signal type of at least one of the first frame or the second frame.

### Claim 5 (depends on 2)

The method according to claim 2, wherein the weight of the spectral pair parameter of the second frame is 0 when a signal type of the first frame is unvoiced, the second frame is the redundancy decoding frame, and a signal type of the second frame is not unvoiced.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the decoded parameter of the first frame comprises an adaptive codebook gain, and wherein performing the post-processing on the decoded parameter of the first frame comprises attenuating an adaptive codebook gain of at least one subframe of the first frame when the first frame is the redundancy decoding frame and a next frame of the first frame is an unvoiced frame.

### Claim 7

A decoder for decoding an audio bitstream, comprising:
a processor; and
a memory coupled to the processor,
wherein the processor is configured to:
perform decoding operations on an audio bitstream comprising a first frame and a second frame, wherein a decoded parameter of the first frame and a decoded parameter of the second frame are acquired via the decoding operations, and wherein the second frame is a previous frame of the first frame;
perform, according to the decoded parameter of the first frame and the decoded parameter of the second frame, post-processing on the decoded parameter of the first frame to obtain a post-processed decoded parameter of the first frame when at least one of the first frame or the second frame is a redundancy decoding frame; and
reconstruct an audio signal using the post-processed decoded parameter of the first frame.

### Claim 8 (depends on 7)

The decoder according to claim 7, wherein the decoded parameter of the first frame comprises a spectral pair parameter of the first frame, the decoded parameter of the second frame comprises a spectral pair parameter of the second frame, and wherein the processor is configured to perform post-processing on the spectral pair parameter of the first frame using the following formula:
lsp[k]=α*lsp_old[k]+δ*lsp_new[k];
wherein 0≤k≤M, lsp[k] is a post-processed spectral pair parameter of the first frame, lsp_old[k] is the spectral pair parameter of the second frame, lsp_new[k] is the spectral pair parameter of the first frame, M is an order of spectral pair parameters, α is a weight of the spectral pair parameter of the second frame, and δ is a weight of the spectral pair parameter of the first frame, and wherein α≥0, δ≥0, and a α+δ=1.

### Claim 9 (depends on 7)

The decoder according to claim 7, wherein the decoded parameter of the first frame comprises a spectral pair parameter of the first frame, the decoded parameter of the second frame comprises a spectral pair parameter of the second frame, and the processor is configured to perform post-processing on the spectral pair parameter of the first frame using the following formula:
lsp[k]=α*lsp_old[k]+β*lsp_mid[k]+δ*lsp_new[k];
wherein 0≤k≤M, wherein lsp[k] is a post-processed spectral pair parameter of the first frame, wherein lsp_old[k] is the spectral pair parameter of the second frame, wherein lsp_mid[k] is a middle value of the spectral pair parameter of the first frame, wherein lsp_new[k] is the spectral pair parameter of the first frame, wherein M is an order of spectral pair parameters, wherein α is a weight of the spectral pair parameter of the second frame, wherein β is a weight of the middle value of the spectral pair parameter of the first frame, and wherein δ is a weight of the spectral pair parameter of the first frame.

### Claim 10 (depends on 9)

The decoder according to claim 9, wherein a value of α, β and δ is determined based on a signal type of at least one of the first frame or the second frame.

### Claim 11 (depends on 10)

The decoder according to claim 10, wherein a value of β is 0 or is less than a preset threshold when the first frame is the redundancy decoding frame, a signal type of the first frame is not unvoiced, and a signal type of a next frame of the first frame is unvoiced.

### Claim 12 (depends on 8)

The decoder according to claim 8, wherein a value of α is 0 when the second frame is the redundancy decoding frame, a signal type of the second frame is not unvoiced, and a signal type of the first frame is unvoiced.

### Claim 13 (depends on 10)

The decoder according to claim 10, wherein the decoded parameter of the first frame comprises an adaptive codebook gain, and wherein the processor is configured to perform post-processing on the adaptive codebook gain of the first frame by attenuating an adaptive codebook gain of at least one subframe of the first frame when the first frame is the redundancy decoding frame and a next frame of the first frame is an unvoiced frame.

### Claim 14

A non-transitory computer readable medium including instructions, which, when executed by a processor, will cause the processor to perform the steps of:
performing decoding operations on an audio bitstream comprising a first frame and a second frame, wherein a decoded parameter of the first frame and a decoded parameter of the second frame are acquired via the decoding operations, and wherein the second frame is a previous frame of the first frame;
performing, according to the decoded parameter of the first frame and the decoded parameter of the second frame, post-processing on the decoded parameter of the first frame to obtain a post-processed decoded parameter of the first frame when at least one of the first frame or the second frame is a redundancy decoding frame; and
reconstructing an audio signal using the post-processed decoded parameter of the first frame.

### Claim 15 (depends on 14)

The non-transitory computer readable medium according to claim 14, wherein the decoded parameter of the first frame comprises a spectral pair parameter of the first frame, the decoded parameter of the second frame comprises a spectral pair parameter of the second frame, and wherein a post-processed spectral pair parameter of the first frame is obtained using the following formula:
lsp[k]=α*lsp_old[k]+δ*lsp_new[k];
wherein 0≤k≤M, lsp[k] is a post-processed spectral pair parameter of the first frame, lsp_old[k] is the spectral pair parameter of the second frame, lsp_new[k] is the spectral pair parameter of the first frame, M is an order of spectral pair parameters, α is a weight of the spectral pair parameter of the second frame, and δ is a weight of the spectral pair parameter of the first frame, and wherein α≥0, δ≥0, and α+δ=1.

### Claim 16 (depends on 15)

The non-transitory computer readable medium according to claim 15, wherein a value of α is 0 when the second frame is the redundancy decoding frame, a signal type of the second frame is not unvoiced, and a signal type of the first frame is unvoiced.

### Claim 17 (depends on 14)

The non-transitory computer readable medium according to claim 14, wherein the decoded parameter of the first frame comprises an adaptive codebook gain, and wherein a post-processed adaptive codebook gain of the first frame is obtained by attenuating an adaptive codebook gain of at least one subframe of the first frame when the first frame is the redundancy decoding frame and a next frame of the first frame is an unvoiced frame.

### Claim 18 (depends on 14)

The non-transitory computer readable medium according to claim 14, wherein the second frame is adjacent to the first frame.

### Claim 19 (depends on 1)

The method according to claim 1, wherein the second frame is adjacent to the first frame.

### Claim 20 (depends on 7)

The decoder according to claim 7, wherein the second frame is adjacent to the first frame.