Method for improvement of G.723.1 processing time and speech quality and for reduction of bit rate in CELP vocoder and CELP vococer using the same
First Claim
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1. A method of searching an MP-MLQ (Multi Pulse Maximum Likelihood Quantization) fixed codebook through predetermination of a grid bit for predicting the positions of pulses during high bit rate decoding of voice signals in a CELP (Code Excited Linear Prediction) vocoder, which reduces process time of G.723.1, the method comprising the steps of:
- generating a target vector divided into odd order and even order pulses;
determining an amplitude of the target vector;
generating composite sound by using the target vector;
comparing the composite sound with an original sound without DC;
determining a grid bit by the comparison;
checking whether the grid bit is zero;
searching the even order pulses when the grid bit is zero;
checking whether the grid bit is one (1);
searching the odd order pulses when the grid bit is one (1); and
searching all of the even and odd order pulses when the grid bit is not zero or one.
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Abstract
A method of searching an MP-MLQ fixed codebook through bit predetermination includes the steps of generating a target vector with amplitude, reducing time to search an optimal pulse array through the bit predetermination and searching all of pulses if two errors have an identical value.
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Citations
4 Claims
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1. A method of searching an MP-MLQ (Multi Pulse Maximum Likelihood Quantization) fixed codebook through predetermination of a grid bit for predicting the positions of pulses during high bit rate decoding of voice signals in a CELP (Code Excited Linear Prediction) vocoder, which reduces process time of G.723.1, the method comprising the steps of:
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generating a target vector divided into odd order and even order pulses;
determining an amplitude of the target vector;
generating composite sound by using the target vector;
comparing the composite sound with an original sound without DC;
determining a grid bit by the comparison;
checking whether the grid bit is zero;
searching the even order pulses when the grid bit is zero;
checking whether the grid bit is one (1);
searching the odd order pulses when the grid bit is one (1); and
searching all of the even and odd order pulses when the grid bit is not zero or one. - View Dependent Claims (2, 3, 4)
wherein the amplitude of the target vector is controlled to be the same for even and odd orders. -
3. The method as claimed in claim 1, wherein the grid bit determining step compares an error value of each grid bit and then determines the grid bit according to
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err0 < err1 1 , if err1 < err0
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4. A CELP (Code Excited Linear Prediction) vocoder implemented by the method described in claim 1.
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Specification