Method and apparatus for speech encoding and decoding by sinusoidal analysis and waveform encoding with phase reproducibility

A speech encoding apparatus in which an input speech signal is divided on a time axis in terms of pre-set encoding units and encoded in terms of the pre-set encoding units, comprising:

• means for detecting a voiced/unvoiced sound state of the input speech signal and classifying the input speech signal into voiced portions and unvoiced portions;
• means for finding short-term prediction residuals of voiced portions of the input speech signal;
• means for encoding the short-term prediction residuals of voiced portions of the input speech signal by sinusoidal analytic encoding;
• and
• means for encoding unvoiced portions of the input speech signal by waveform encoding.

A speech decoding method for decoding an encoded speech signal obtained by encoding a voiced portion of an input speech signal with first encoding comprising sinusoidal analytic encoding and by encoding an unvoiced portion of the input speech signal with second encoding employing short-term prediction residuals, comprising the steps of:

• finding first short-term prediction residuals for the voiced speech portion of the encoded speech signal by sinusoidal synthesis;
• finding second short-term prediction residuals for the unvoiced speech portion of the encoded speech signal;
• and
• employing predictive synthetic filtering for synthesizing first and second time-axis waveforms based on the first and second short-term prediction residuals of the voiced and unvoiced speech portions, respectively.

A speech decoding apparatus for decoding an encoded speech signal obtained by encoding voiced portions of an input speech signal with a first encoding and by encoding unvoiced portions of the input speech signal with a second encoding, comprising:

• means for finding short-term prediction residuals for the voiced portions of the input speech signal by sinusoidal analytic encoding;
• means for finding short-term prediction residuals for the unvoiced portions of said encoded speech signal;
• and
• predictive synthetic filtering means for synthesizing a first time-axis waveform based on said short-term prediction residuals of the voiced speech portions and for synthesizing a second time-axis waveform based on the short-term prediction residuals of the unvoiced speech portions.

A speech decoding method for decoding an encoded speech signal obtained by finding short-term prediction residuals of an input speech signal and encoding resulting short-term prediction residuals with sinusoidal analytic encoding, comprising the steps of:

• finding said short-term prediction residuals of said encoded speech signal by sinusoidal synthesis;
• adding noise controlled in amplitude based on said encoded speech signal to said short-term prediction residuals found by said sinusoidal synthesis;
• and
• performing predictive synthetic filtering by synthesizing a time-domain waveform based on said short-term prediction residuals found by said sinusoidal synthesis added to said noise.

A speech decoding apparatus for decoding an encoded speech signal obtained by finding short-term prediction residuals of an input speech signal and encoding said resulting short-term prediction residuals with sinusoidal analytic encoding, comprising:

• sinusoidal synthesis means for finding said short-term prediction residuals of said encoded speech signal by sinusoidal synthesis;
• noise addition means for adding noise controlled in amplitude based on said encoded speech signal to said short-term prediction residuals;
• and
• predictive synthetic filtering means for synthesizing a time-domain waveform based on said short-term prediction residuals found by said sinusoidal synthesis means added to said noise.

A portable radio terminal apparatus comprising:

• amplifier means for amplifying an input speech signal;
• A/D conversion means for performing analog to digital conversion of an output signal from said amplifier means;
• speech encoding means for speech-encoding an output signal from said A/D conversion means;
• transmission path encoding means for channel coding an output signal from said speech encoding means;
• modulation means for modulating an output signal from said transmission path encoding means;
• D/A conversion means for performing digital to analog conversion of an output signal from said modulation means;
• and
• amplifier means for amplifying an output signal from said D/A conversion means and supplying the resulting amplified signal to an antenna;
• wherein said speech encoding means comprises:
• means for detecting a voiced/unvoiced sound state of the input speech signal and classifying the input speech signal into voiced portions and unvoiced portions;
• predictive encoding means for finding short-term prediction residuals of voiced portions of the input speech signal;
• sinusoidal analytic encoding means for encoding the short-term prediction residuals of voiced portions of the input speech signal by sinusoidal analytic encoding;
• and
• waveform encoding means for waveform encoding of unvoiced portions of the input speech signal.

A portable radio terminal apparatus comprising:

• amplifier means for amplifying a received signal;
• A/D conversion means for performing analog to digital conversion of an output signal from said amplifier means;
• demodulating means for demodulating an output signal from said A/D conversion means;
• transmission path decoding means for channel decoding an output signal from said demodulating means;
• speech decoding means for speech-decoding an output signal from said transmission path decoding means;
• and
• D/A conversion means for performing digital to analog conversion of an output signal from said demodulating means;
• wherein said speech decoding means comprises:
• sinusoidal synthesis means for finding short-term prediction residuals of said encoded speech signal by sinusoidal synthesis;
• noise addition means for adding noise controlled in amplitude based on said encoded speech signal to said short-term prediction residuals;
• and
• a predictive synthetic filter for synthesizing a time-domain waveform based on the short-term prediction residuals added to the noise.