Samsung Electronics Co., Ltd.

Yong-duk Cho

Moo-young Kim

Hong-kook Kim

Sang-ryong Kim

A variable dimension spectral magnitude quantization apparatus and method using a predictive and mel scale binary vector is provided. The apparatus according to linear prediction spectral envelope and residual spectral envelope quantization using low order linear prediction modeling and residual spectrum modeling, includes a predictive quantizer for obtaining a predictive-quantized first residual spectral envelope from a quantized previous residual spectral envelope, a mel-scale binary vector quantizer for obtaining a second residual spectral envelope represented with a linear scale code vector using a mel-scale binary vector codebook, a synthesized spectral envelope generator for adding the output of the predictive quantizer and the output of the mel-scale binary vector quantizer to generate a quantized residual spectral envelope and multiplying the quantized residual spectral envelope by a corresponding quantized linear prediction spectral envelope to generate a synthesized spectral envelope, a comparator for comparing the synthesized spectral envelope with an original spectral envelope, and a minimum value detector for detecting a minimum value from the values sequentially obtained by the comparator.

Variable dimension spectral magnitude quantization apparatus and method using predictive and mel-scale binary vector

An apparatus for quantizing a spectral envelope with noise robustness showing high performance even under a background noise environment and a channel noise environment, and a method therefor, are provided. The spectral envelope quantizing apparatus includes a spectral envelope quantizing apparatus with noise robustness for representing a spectral envelope of speech by a minimum number of bits for the optimal coding of a speech signal. The apparatus includes a line spectrum frequencies (LSFs) input portion for converting linear predictive coding coefficients extracted from the speech into Nth order line spectrum frequencies coefficients and inputting the coefficients as the LSFs of a current frame. It also includes a linked split-vector quantizing portion for dividing the LSFs into a predetermined number of linked sub-vectors and quantizing the sub-vectors, and a predictive linked split-vector quantizing portion for obtaining the difference between the LSFs and the LSFs of a previous frame and vector-quantizing the difference. The apparatus further includes an error selector for comparing the error values of the LSFs quantized in the linked split-vector quantizing portion and the predictive linked split-vector quantizing portion, selecting the codebook index of the quantized LSFs having the smaller error value, and outputting the selected codebook index together with a mode bit.

Apparatus for quantizing spectral envelope including error selector for selecting a codebook index of a quantized LSF having a smaller error value and method therefor

A method and an apparatus for determining multiband voicing levels using a frequency moving method in a vocoder are provided. The method for determining the multiband voicing levels using the frequency moving method according to the present invention in the vocoder includes the steps of (a) applying a window to an input voice signal and obtaining a power spectrum from a voice spectrum obtained by Fourier converting a windowed signal, (b) moving the frequency of each subband to an origin after dividing the power spectrum into a predetermined number of subbands, (c) obtaining autocorrelation values of the respective subbands by inverse Fourier converting the power spectrum the frequency of which is moved to the origin, and (d) normalizing the respective autocorrelation values and determining the voicing levels of the subbands from the normalized autocorrelation values.

Method and apparatus for determining multiband voicing levels using frequency shifting method in vocoder

A pitch determination apparatus and method using spectro-temporal autocorrelation to prevent pitch determination errors are provided. The pitch determination apparatus using spectro-temporal autocorrelation includes a formant bandwidth extension unit for extending a formant bandwidth to reduce the influence of the first formant with respect to an input voice, a temporal autocorrelation calculation unit for calculating an autocorrelation value of a time axial voice within a candidate pitch range with respect to a time axial speech signal output from the formant bandwidth extension unit, a spectral autocorrelation calculation unit for transforming the time axial speech signal output from the formant bandwidth extension unit into a frequency axial signal, and calculating an autocorrelation value between frequency axis amplitude spectrums within the candidate pitch range, an autocorrelation value synthesis unit for summing the autocorrelation values obtained by the temporal and spectral autocorrelation calculation units and obtaining a spectro-temporal autocorrelation value, and a pitch determination unit for determining a pitch having a maximum spectro-temporal autocorrelation value as a final pitch. According to this apparatus, pitch determination errors are reduced by determining a pitch using the temporal and spectral autocorrelation values, thus improving the quality of speech communication.

Pitch determination apparatus and method using spectro-temporal autocorrelation

A of estimating a pitch in a multiband excitation vocoder is provided. The method includes the steps of (a) obtaining an error amount with respect to respective pitch candidates in a predetermined pitch area from an input voice magnitude spectrum, (b) obtaining a weighted function with respect to the respective pitch candidates, (c) obtaining a weighted error amount with respect to the respective pitch candidates, and (d) determining the candidate pitch having the minimum error amount in the weighted error amount with respect to the respective pitch candidates to be an estimated pitch. According to the present invention, in the vocoder of the multiband excitation method, it is possible to obtain high speech quality due to a short delay time since it is possible to remove a gross pitch error without using a pitch tracking method.

Pitch estimation method for a low delay multiband excitation vocoder

In a voice coding and decoding method and apparatus using an RCELP technique, a CELP-series decoder can be obtained at a low transmission rate. A voice spectrum is extracted by performing a short-term linear prediction on voice signal. An error range in a formant region is widened during adaptive and renewal codebook search by passing said preprocessed voice through a formant weighting filter and widening an error range in a pitch on-set region by passing the same through a voice synthesis filter and a harmonic noise shaping filter. An adaptive codebook is searched using an open-loop pitch extracted on the basis of the residual minus of a speech. A renewal excited codebook produced from an adaptive codebook excited signal is searched. Finally, a predetermined bit is allocated to various parameters to form a bit stream.

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Suwon, South Korea

Yong-duk Cho