Method and device for selecting conductivity coefficient vector quantization

Abstract

The invention discloses a method and a device for quantifying the vectors of the induced spectrum frequency (ISF) coefficients, which includes the steps as follows: the ISF coefficients are divided into at least two groups of sub-vectors; the inter-frame strong- and weak-correlation vectors of the induced spectrum are quantified for each group of sub-vectors; the residual signals are calculated after the strong- and weak-correlation vectors are quantified; the quantification errors of the above residual signals are also calculated; the quantification errors of the strong- and weak-correlation residual signals are judged for each group of sub-vectors; and the ISF coefficient vectors of the correlation manner with less quantification error in each group are quantified. The invention is based on the short-time correlation and the long-time correlation of the induced spectrum frequency coefficients, and different forecast coefficients are hereby applied to different dimension of the induced spectrum frequency coefficients, thus increasing forecast gains, narrowing the variation range of the residual signals, enhancing the accuracy for the ISF coefficients quantification, achieving clear quantification, and improving the quality for broadband phonetic coding.

Description

technical field [0001] The invention relates to the technical field of digital speech coding, in particular to a method and a device for vector quantization of selected pilot spectrum frequency (ISF) coefficients. Background technique [0002] The linear prediction coefficient (LPC) of the speech signal can more accurately represent the short-term amplitude spectrum envelope of the speech signal, and is applied in the current medium and low-rate speech coding: such as Code Excitation Linear Prediction (CELP, Code Excitation Linear Prediction), many With excitation coding (MBE, MultibandExcitation Coding), waveform interpolation coding (WI, Waveform Interpolation), etc., but the LPC coefficient has a wide dynamic range and instability in the synthesis filter, so the LPC coefficient is not suitable for direct quantization. In view of the above problems, it is necessary to convert LPC to other representations in the research of speech spectral envelope quantization to ensure th...

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Problems solved by technology

[0023] However, the existing technology does not consider the characteristics of the spectral frequency (ISF) coefficient itself, and does not distinguish between strong and weak correlations. The quantization method is relatively simple, resulting in relatively large quantization errors and damaging the quality of wideband speech coding.

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