An adaptive transform coder is proposed that makes effective use of vector quantization. It is aimed at medium-band (4. 8-9. 6 kbps) speech coding. To minimize waveform distortion, discrete Fourier transform (DFT) coefficients of the linear prediction residue are quantized using two novel techniques: information has been adaptively allocated so as to obtain SNR gain, and quantization has been divided into two (vector-scalar) stages for a higher bit rate. Subjective quality at 7. 2 kbps in comparable to that for a 5 bit log PCM. The coder is resistant to background noise.
|Number of pages||9|
|Journal||Reports of the Electrical Communication Laboratory|
|Publication status||Published - 1986 Jan 1|
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