Keunseok Cho

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In this paper, a new algorithm for encoding spectral envelope in G.729.1 for VoIP is proposed. In the TDAC part of G.729.1, the spectral envelope and MDCT coefficients extracted in the weighted CELP coding error (lower-band) and the higher-band input signal are encoded. In order to reduce allocation bits for spectral envelope coding, a new algorithm using(More)
We certify that this work has passed the scholastic standards requested by the Information and Communications University as a thesis Abstract In this thesis, an improved SEW/REW decomposition method with pitch-dependent phase generation and a noble variable bit rate (VBR) scheme are proposed to enhance the speech quality of the waveform interpolation (WI)(More)
In this paper, an efficient noise reduction algorithm is proposed for robust speech recognition. For the nonstationary noise reduction, frequency-domain beamforming-based speech enhancement is performed and masking-based Wiener filter is applied to the beamforming output. To design the masking-based Wiener filter, the spectrum of beamforming output is(More)
This letter proposes a bandwidth extension (BWE) method using the cepstral envelope coding and duplication of quantized wideband (WB) signals by means of analysis -by-synthesis (AbS) for super-wideband (SWB) coders. In the proposed method, a high frequency band is generated by utilizing the quantized cepstral coefficients extracted from the envelope and the(More)
In this paper, we proposed an improved SEW/REW decomposition method with pitch-dependent phase generation and a noble VBR scheme for bit rate reduction in waveform interpolative coders. The proposed decomposition is performed in the magnitude domain to reduce spectral distortions. The phase of the characteristic waveforms is generated after classifying the(More)
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