Voice coding process and device for implementing said process
First Claim
1. A process for coding a voice signal comprising a block of a predetermined number of samples corresponding to a voiced segment of speech wherein said voice signal is analyzed by being split into a low frequency (LF) bandwidth and a high frequency bandwidth the signal contents of which are to be coded separately, said process being characterized in that it includes:
- coding said low frequency bandwidth signal;
processing said high frequency-bandwidth contents to derive therefrom high frequency bandwidth energy information;
processing both said low frequency bandwidth and said high frequency bandwidth contents to derive therefrom information relative to the phase shift between said high frequency signal and said low frequency signal;
coding separately said high frequency bandwidth energy information and said phase shift information;
grouping into a set of descriptors for transmission said coded low frequency bandwidth signal, said coded high frequency bandwidth energy information and said coded phase shift information to form the coded representation of said voice signal.
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Abstract
The voice signal is analyzed to derive therefrom a low frequency base band signal, linear prediction coefficients and high frequency (HF) descriptors. Said HF descriptors include HF energy indications as well as indications relative to the phase shift between the low frequency and the high frequency band. Said HF descriptors are used during the voice synthesis operation to provide an inphase HF bandwidth component to be added to the base band prior to be used for driving a linear prediction synthesis filter tuned using said linear prediction parameters.
109 Citations
17 Claims
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1. A process for coding a voice signal comprising a block of a predetermined number of samples corresponding to a voiced segment of speech wherein said voice signal is analyzed by being split into a low frequency (LF) bandwidth and a high frequency bandwidth the signal contents of which are to be coded separately, said process being characterized in that it includes:
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coding said low frequency bandwidth signal; processing said high frequency-bandwidth contents to derive therefrom high frequency bandwidth energy information; processing both said low frequency bandwidth and said high frequency bandwidth contents to derive therefrom information relative to the phase shift between said high frequency signal and said low frequency signal; coding separately said high frequency bandwidth energy information and said phase shift information;
grouping into a set of descriptors for transmission said coded low frequency bandwidth signal, said coded high frequency bandwidth energy information and said coded phase shift information to form the coded representation of said voice signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A Voice Excited Predictive Coder (VEPC) including first means sensitive to the voice signal for generating spectral descriptors representing linear prediction parameters, second means for generating a low frequency or base band signal (x(n)) and third means for generating high frequency (HF) or upper band signal descriptors of the upper band signal y(n), said third means including:
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base band preprocessing means connected to said second means for generating a pitch parameter M and a cleaned base band pulse train z(n); phase evaluation means connected to said base band preprocessing means and sensitive to said upper band signal to derive therefrom a phase shift descriptor K; phase shifter means sensitive to said base band pulse train z(n) and to said phase shift descriptor K to derive therefrom a shifted pulse train z(n-K); upper band analysis means sensitive to said upper band signal y(n), to said shifted pulse train z(n-K) and to said pitch parameter M, to derive therefrom noise energy information E and HF amplitude information A(i); and
,coding means for coding said phase shift descriptor K, amplitude A(i), noise energy E and base band signal x (n). - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification