Variable rate speech coding using perceptive thresholds and adaptive VUS detection

This paper proposes a variable bitrate wideband CELP coding scheme (50-7000 Hz) with a one-way coder-decoder delay of 25 ms only. The bitrate varies between 6.4 kbit/s and 14.8 kbit/s with a mean of 11.2 kbit/s at a voice activity of 95%. The variation of the bitrate is based on a voiced-unvoiced-silence classification of the speech frame to be encoded. For voiced frames a perceptually based focussed LTP analysis is used, and f o r unvoiced or silent f m m e s the LTP filter is omitted. Additionally, in adjacent frames with small spectral changes LPC parameters are repeated using an adaptive LPC codebook. For the classification of the dijferent modes a cepstral distance measure, and a new adaptive detector is used. By informal listening tests the speech quality was rated higher than the CCITT G.722 wideband ccdec operating at 48 kbit/s.

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Variable rate speech coding using perceptive thresholds and adaptive VUS detection

Cited by 3 publications

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State of the art and trends in speech coding

State of the art and trends in speech coding

Design and use of speech recognition algorithms for a mobile radio telephone

Variable Bitrate Wideband Speech Coding Using Perceptually Motivated Thresholds

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