DEVICE AND METHOD FOR CODING/DECODING VOICE CONTAINING SILENCE VOICE CODING AND STORAGE MEDIUM RECORDING PROGRAM

Japanese Patent JP3451998

B2

PROBLEM TO BE SOLVED: To reduce deterioration in decoded voice quality caused by discontinuity of a filter coefficient by decoding a characteristic parameter showing a spectrum envelope characteristic of a composite signal with a value smoothened in the time direction.
SOLUTION: A parameter decode circuit 54 outputs the filter coefficient and an RMS obtained from a signal code line inputted from an input terminal 52 to smoothing circuits 64, 66. The smoothing circuit 64 smoothens the filter coefficient to output it to a synthetic circuit 68. However, when the matter that the signal code line isn't transmitted with a DTX decision code inputted from the input terminal 50 is shown, the filter coefficient of the former frame is used. The synthetic circuit 68 inputs an exciting signal from a mixer circuit 61 to the filter constituted of the filter coefficient from the smoothing circuit 64, and decodes the signal to output it from an output terminal 70. When a silence voice section is decoded, after the intermittently transmitted filter coefficient is smoothing processed like the RMS, a synthetic filter is used, and the discontinuous change of the filter coefficient is prevented, and the decoded voice quality is improved.

Masahiro Serizawa
Hironori Ito

JP29879599A

September 29, 2003

October 20, 1999

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NEC

G10L25/78; G10L13/00; G10L19/012; G10L19/06; G10L19/16; H04B14/04; (IPC1-7): G10L11/02; G10L13/00

JP7334197A
JP62102300A
JP9149104A

Masahiko Desk (2 outside)

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