Method and device for encoding wideband speech

A wideband speech encoding method comprising:

• sampling the speech to obtain successive voice frames each comprising a predetermined number of samples, and each voice frame having parameters of a code-excited linear prediction model, the parameters comprising a long-term excitation digital word extracted from an adaptive coded directory, and, an associated long-term gain, and a short-term excitation word extracted from a fixed coded directory and, an associated short-term gain;
• and
• updating the adaptive coded directory on the basis of the extracted long-term excitation word and of the extracted short-term excitation word, and comprising
• adding the product of the long-term excitation digital word times the associated long-term gain with the product of the short-term excitation word times the associated short-term gain to generate a summed digital word, and
• filtering the summed digital word to obtain a filtered word, and
• updating the adaptive coded directory with the filtered word.

A wideband speech encoding device comprising:

• sampling means for sampling the speech to obtain successive voice frames each comprising a predetermined number of samples;
• processing means for determining parameters of a code-excited linear prediction model with each voice frame, and comprising first extraction means for extracting a long-term excitation digital word from an adaptive coded directory and calculating an associated long-term gain, and second extraction means for extracting a short-term excitation word from a fixed coded directory and calculating an associated short-term gain;
• and
• first updating means for updating the adaptive coded directory on the basis of the extracted long-term excitation word and of the extracted short-term excitation word, and comprising
• first calculation means for summing the product of the long-term excitation extracted word times the associated long-term gain, with the product of the short-term excitation extracted word times the associated short-term gain, to deliver a summed digital word, and
• a low-pass filter having a cutoff frequency greater than a quarter and less than a half of a sampling frequency to generate a filtered word, and connected between an output of the first calculation means and the adaptive coded directory to update the adaptive directory with the filtered word.

A wideband speech encoding device comprising:

• a sampler to sample the speech to obtain successive voice frames each comprising a predetermined number of samples;
• a processor to determine parameters of a code-excited linear prediction model with each voice frame, and comprising a first extractor to extract a long-term excitation digital word from an adaptive coded directory and calculate an associated long-term gain, and a second extractor to extract a short-term excitation word from a fixed coded directory and calculate an associated short-term gain;
• and
• a first updating unit to update the adaptive coded directory on the basis of the extracted long-term excitation word and of the extracted short-term excitation word, and comprising
• a first calculation unit to add the product of the long-term excitation extracted word times the associated long-term gain, with the product of the short-term excitation extracted word times the associated short-term gain, to deliver a summed digital word, and
• a low-pass filter to generate a filtered word, and connected between an output of the first calculation unit and the adaptive coded directory to update the adaptive coded directory with the filtered word.