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United States Patent | 4,791,670 |
Copperi , et al. | December 13, 1988 |
This method provides a filtering of digital samples of speech signal by a linear-prediction inverse filter, whose coefficients are chosen out of a codebook of quantized filter coefficient vectors, obtaining a residual signal subdivided into vectors. The weighted mean-square error made in quantizing said vectors with quantized residual vectors contained in a codebook and forming excitation waveforms is computed. The coding signal for each block of samples consists of the coefficient vector index chosen for the inverse filter as well as of the indices of the vectors of the excitation waveforms which have generated minimum weighted mean-square error. During the decoding phase, a synthesis filter, having the same coefficients as chosen for the inverse filter, is excited by quantized-residual vectors chosen during the coding phase (FIGS. 1, 2).
Inventors: | Copperi; Maurizio (Venaria, IT), Sereno; Daniele (Vercelli, IT) |
Assignee: |
Cselt - Centro Studi e Laboratori Telecomunicazioni SpA
(Turin,
IT)
|
Appl. No.: | 06/779,089 |
Filed: | September 20, 1985 |
Nov 13, 1984 [IT] | 68134 A/84 | |||
Current U.S. Class: | 704/222 ; 704/226; 704/E19.017; 704/E19.024; 704/E19.035 |
Current International Class: | G10L 19/12 (20060101); G10L 19/00 (20060101); G10L 19/06 (20060101); G10L 19/02 (20060101); G10L 005/00 () |
Field of Search: | 381/36,41,43,46,51 364/513,513.5,518 358/12,21R |
4670851 | June 1987 | Murakami et al. |
WO85/04276 | Sep., 1985 | WO | |||
2150377 | Jun., 1985 | GB | |||
"Distortion Performance of Vector Quantization for LPC Voice Coding", Biing-Hwang Juang et al-pp. 294-303. . "A New Model of LPC Excitation for Producing Natural-Sounding Speech at Low Bit Rates", B. S. Atal et al, pp. 614-617. . IEEE Transactions on Communications, vol. Com. 30, No. 4, Apr. 1982, A Multirate Voice Digitizer Based upon Vector Quantization by Guillermo Rebolledo, Member IEEE et al. pp. 721-727.. |