Patent ID: 6073092
Filing Date: 2000-06-06
Classification: G10L

Abstract:
A method for speech coding based on a code excited linear prediction (CELP) model comprising:(a) dividing speech at a sending station into discrete speech samples;(b) digitizing the discrete speech samples;(c) forming a mixed excitation function by selecting a combination of two codevectors from two fixed codebooks, each having a plurality of codevectors, and selecting a combination of two codebook gain vectors from a plurality of codebook gain vectors;(d) selecting an adaptive codevector from an adaptive codebook, and selecting a pitch gain in combination with the mixed excitation function to represent the digitized speech;(e) encoding one of the two selected codevectors, both of the selected codebook gain vectors, the adaptive codevector and the pitch gain as a digital data stream;(f) sending the digital data stream from the sending station to a receiving station using transmission means;(g) decoding the digital data stream at the receiving station to reproduce the selected codevector, the two codebook gain vectors, the adaptive codevector, the pitch gain, and LPC filter parameters;(h) reproducing a digitized speech sample at the receiving station using the selected codevector, the two codebook gain vectors, adaptive codevector, the pitch gain, and the LPC filter parameters;(i) converting the digitized speech sample at the receiving station into an analog speech sample; and(j) combining a series of analog speech samples to reproduce the coded speech; andwherein encoding one of the two selected codevectors, both of the selected codebook gain vectors, the adaptive codevector and pitch gain as a digital data stream further comprises:adjusting the baseline codevector by the baseline gain and adjusting the implied codevector by the implied gain to form a mixed excitation function;using the mixed excitation function as an input to a pitch filter;using the output of the pitch filter as an input of a linear predictive coding synthesis filter; andsubtracting the output from the linear predictive coding synthesis filter from the speech to form an input to a weighting filter.