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Pulse allocating method in voice coding

A technology of pulse distribution and speech coding, applied in speech analysis, instruments, etc., can solve the problem of not supporting stereo speech signal AMR-WB speech coding, etc.

Inactive Publication Date: 2008-01-30
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] In addition, in the ITU-T recommendation G.722.2, although AMR-WB speech coding for monophonic speech signals is currently supported, it does not support stereo speech signals AMR-WB Speech Coding

Method used

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  • Pulse allocating method in voice coding
  • Pulse allocating method in voice coding
  • Pulse allocating method in voice coding

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Embodiment approach 1

[0028] In this embodiment, the allocation of the number of pulses to each channel is determined based on the degree of similarity among the channels of the input stereo signal, and the periodicity and stability of each channel. Each channel is assigned the desired number of pulses based on similarity, periodicity and stability. After the number of pulses allocated to each channel is determined, the same pulse search as in general AMR-WB speech coding is performed to determine the pulse position for each channel. These pulses are encoded as groups of codewords and sent as a codebook index as one of the parameters in the speech bitstream.

[0029] FIG. 2 shows the main processing flow of speech coding in this embodiment.

[0030] First, at ST (step) 11, the stereo signal is pre-processed, which includes down-sampling and filtering using a high-pass filter and a pre-emphasis filter.

[0031] In ST12, LPC analysis is performed on the preprocessed stereo signal to obtain the LPC ...

Embodiment approach 2

[0071] In this embodiment, K is determined based on the characteristics of the speech signal 1 、K 2 , and make the pulse distribution between each channel adaptively change. For example, the distribution ratio of the number of pulses to each channel can be calculated based on the periodicity and MAF of the audio signal of each channel.

[0072]For example, when both the L channel and the R channel are "stable and vocal", K is calculated by formula (2) 1 .

[0073] K 1 = α 1 τ R τ L + τ R ...Formula (2)

[0074] In formula (2), τ L , τ R are the pitch period of the L channel and the pitch period of the R channel respectively, α 1 is used to fine-tune K 1 coefficient. According to Equation (2), more pulses ca...

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Abstract

A pulse distribution method capable of efficiently encoding stereo speech signals. In the fixed codebook search (ST21-ST25) of this pulse allocation method, the comparison of stereo signals is carried out for each subframe, the similarity between channels is judged (ST21), and the characteristics of stereo signals are judged (ST22). The similarity between and the characteristics of the stereo signal determine the number of pulses (ST23) allocated to each channel, perform a pulse search and determine the pulse position (ST24) of each channel, and encode the pulses determined in ST24 ( ST25).

Description

technical field [0001] The present invention relates to a pulse distribution method in speech coding. Background technique [0002] In general, in speech coding, a vocal tract model is used to synthesize a speech signal that resembles the original speech as closely as possible. As one of such speech coding, there is Adaptive Multi-Rate Wideband (AMR-WB: Adaptive MultiRate-WideBand) speech coding used in the 3GPP system (see Non-Patent Document 1). This AMR-WB speech coding is also selected and accepted by ITU-T as ITU-T Recommendation G.722.2 (Non-Patent Document 2). Next, AMR-WB speech coding using a bit rate of 23.85 kbps will be described by way of example. [0003] As one of the important structural elements of AMR-WB speech coding, there is the search of a fixed codebook (Fig. 1). In AMR-WB speech coding, a frame having downsampled speech samples of 256 samples is divided into 4 subframes each having 64 samples. In the process of searching the fixed codebook, the su...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G10L19/10G10L19/00G10L19/008G10L19/16
CPCG10L19/10G10L19/008
Inventor 张峻伟梁世丰吉田幸司后藤道代
Owner PANASONIC CORP
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