VOICE ENCODING AND DECODING DEVICE INCLUDING VOICELESS ENCODING, DECODING METHOD, AND RECORDING MEDIUM HAVING PROGRAM RECORDED THEREON

摘要

PROBLEM TO BE SOLVED: To provide a device which reduces sound quality deterioration when a voiceless section is encoded at a very low bit rate. SOLUTION: The device is equipped with: a switching means for passing a signal code sequence to a voice part decoding means or voiceless part decoding means according to whether an input signal is in a voiced or voiceless section on the basis of a VAD decision code outputted from a bit sequence decomposing means; a parameter decoding means which outputs a filter coefficient and RMS that the voiceless part decoding means derives from the signal code sequence; a smoothing means which smoothes and outputs the RMS and filter coefficient outputted from the parameter decoding means; a pulse generating means which generates a pulse train signal consisting of pulses having positions and amplitudes generated with random numbers; a pitch generating means which generates a pitch signal; a mixing means which generates an excitation signal of a synthesizing filter by performing linear sum processing between a random number signal, the pulse train signal passed from the pulse generating means and the pitch signal; and a synthesizing means which decodes and outputs the excitation signal by inputting the excitation signal to a filter composed of a smoothed filter coefficient. COPYRIGHT: (C)2003,JPO