Abstract: An excitation vector generator includes an input vector providing system that is capable of providing an input vector having at least one pulse, each pulse having a predetermined position and a respective polarity. A fixed waveform storage system is capable of storing at least one fixed waveform. An arranging system is capable of arranging the at least one fixed waveform in accordance with the position and the polarity of the at least one pulse.

Abstract: The present invention carries out pre-selection on many LPC codevectors stored in an LSF codebook 101 using a weighted Euclidean distortion as a measure and carries out a full-code selection on the LPC codevectors left after the pre-selection using an amount of distortion in a spectral space as a measure. This makes it possible to improve the quantization performance of the LPC parameter vector quantizer and improve the quality of synthesized speech of the speech coder/decoder.

Abstract: CELP-based speech encoder that performs encoding by decomposing one frame into a plurality of subframes, includes an LPC synthesizer that obtains synthesized speech by filtering an adaptive excitation vector and a stochastic excitation vector stored in an adaptive codebook and in an stochastic codebook using LPC coefficients obtained from input speech. A gain calculator calculates gains of the adaptive excitation vector and the stochastic excitation vector. A parameter coder performs vector quantization of the adaptive excitation vector and the stochastic excitation vector obtained by comparing distortions between the input speech and the synthesized speech. A pitch analyzer performs pitch analyses of a plurality of subframes in the frame respectively, before performing an adaptive codebook search for the first subframe, calculating correlation values and finding a value most approximate to the pitch period using the correlation values.

Abstract: An excitation vector generator is provided for generating an excitation vector. The excitation vector includes a pulse vector generator that has at least one channel for generating pulse vectors. A memory stores at least one type of dispersion pattern for each of the channels. A dispersion pattern is selectively extracted from the memory for each of the channels. A dispersed vector generator generates a dispersed vector for every channel by convolution calculation using the extracted dispersion pattern and the generated pulse vectors. An excitation vector generator generates an excitation vector from the dispersed vectors generated by the dispersion vector generator.

Abstract: A target vector is coded by multi-stage vector quantization. A first stage of the coding of the target vector is performed using a first code vector stored in a first codebook. A scalar associated with a code of each first code vector is stored in an amplifier storing section. A third code vector is determined by multiplying a second code vector stored in a second codebook with the scalar, calculating a distance using the target vector, the first code vector and the third code vector, and performing a second stage of the coding of the target vector using a result of the distance calculation.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds. This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.

Abstract: A speech encoder includes an LPC synthesizer that obtains synthesized speech by filtering an adaptive excitation vector and a stochastic excitation vector stored in an adaptive codebook and in a stochastic codebook using LPC coefficients obtained from input speech. A gain calculator calculates gains of the adaptive excitation vector and the stochastic excitation vector and searches code of the adaptive excitation vector and code of the stochastic excitation vector by comparing distortions between the input speech and the synthesized speech obtained using the adaptive excitation vector and the stochastic excitation vector. A parameter coder performs predictive coding of gains using the adaptive excitation vector and the stochastic excitation vector corresponding to the codes obtained. The parameter coder comprises a prediction coefficient adjuster that adjusts at least one prediction coefficient used for the predictive coding according to at least one state of at least one previous subframe.

Abstract: An apparatus sets a pitch cycle search object in pitch cycle search processing for searching for a pitch cycle included in a linear predictive residual on a per subframe basis. A pitch cycle indicator of the apparatus sequentially output spitch cycle candidates within a predetermined pitch cycle search range at integral accuracy. A memory stores an integral component of a pitch cycle selected in pitch cycle search processing of a previous subframe. An adaptive sound source vector generator sets, as the pitch cycle search object in pitch cycle search processing in a processing subframe section, a group of candidates comprising a group of integral-accuracy pitch cycle candidates output from the pitch cycle indicator and a group of fractional-accuracy pitch cycle search candidates that cover a pitch cycle near an integral component of the pitch cycle read from the previous subframe integral pitch cycle memory using fractional accuracy.

Abstract: An excitation vector generator includes an input vector provider configured to provide an input vector having at least one pulse, each pulse having a pre-determined position and a respective polarity. An arranger is configured to arrange a waveform in accordance with the position and the polarity of the pulse. A shape of the waveform comprises a pulse-like shape and a length of the waveform is shorter than a length of a sub-frame.

Abstract: An Adaptive Sound Source Vector Generator (ASSVG) 103 sets preceding and succeeding pitch cycles centered on an integral-accuracy pitch cycle T0 selected in the previous subframe as a range for searching for a fractional-accuracy pitch frequency, and extracts an adaptive sound source vector P(T-frac) that has fractional-accuracy pitch cycle T-frac within this range from an Adaptive Code Book (ACB) 102. A Last Sub Frame Integral Pitch Cycle Storage (LSFIPCS) 108 stores integral component T0 of the optimal pitch cycle selected by a Distortion Comparator (DC) 107, and when a pitch cycle of the next subframe is searched for, outputs this optimal pitch cycle integral component T0 to the Adaptive Sound Source Vector Generator (ASSVG) 103. An Optimal Pitch Cycle Accuracy Judge Section (OPCAJS) 109 judges whether the optimal pitch cycle is of integral accuracy or fractional accuracy.

Abstract: A dispersed vector generator used for a speech encoder or a speech decoder includes a pulse vector provider that provides a pulse vector having a signed unit pulse on one element of a vector axis. A dispersion pattern determiner determines a dispersion pattern of a set of waveforms defined before a start of encoding or decoding. A dispersed vector generator convolutes the pulse vector and the determined dispersion pattern to generate a dispersed vector. A length of the waveforms is shorter than a length of a sub-frame.

Abstract: An excitation vector generator includes an input vector providing system that is capable of providing an input vector having at least one pulse, each pulse having a predetermined position and a respective polarity. A fixed waveform storage system is capable of storing at least one fixed waveform. An arranging system is capable of arranging the at least one fixed waveform in accordance with the position and the polarity of the at least one pulse.

Abstract: First codebook 61 and second codebook 62 respectively have two subcodebooks, and in respective codebooks, addition sections 66 and 67 obtain respective excitation vectors by adding sub-excitation vectors fetched from respective two subcodebooks. Addition section 68 obtains an excitation sample by adding those excitation vectors. According to the aforementioned constitution, it is possible to store sub-excitation vectors with different characteristics in respective sub-codebooks. Therefore, it is possible to correspond to input signals with various characteristics, and achieve excellent sound qualities at the time of decoding.

Abstract: First codebook and second codebook respectively have two subcodebooks, and in respective codebooks, addition sections obtain respective excitation vectors by adding sub-excitation vectors fetched from respective two subcodebooks. Addition section obtains an excitation sample by adding those excitation vectors. According to the aforementioned constitution, it is possible to store sub-excitation vectors with different characteristics in respective sub-codebooks. Therefore, it is possible to correspond to input signals with various characteristics, and achieve excellent sound qualities at the time of decoding.

Abstract: In coding and decoding an acoustic parameter, a weighted vector is generated by multiplying a code vector output in a past frame and a code vector selected in a present frame by weighting factors respectively selected from a factor code book and adding the products to each other.

Abstract: A code excited linear prediction speech decoder is provided. An adaptive codebook generates an adaptive code vector. A random codebook generates a random code vector. A synthesis filter receives a signal based on the adaptive code vector and the random code vector, and performs linear prediction coefficient synthesis on the signal. The random codebook includes a pulse vector provider that provides a pulse vector having a signed unit pulse, a comparator that compares a value of adaptive codebook gain with a preset threshold value, a selector that selects a dispersion pattern from a plurality of dispersion patterns stored in a memory in accordance with a result of the comparison, and a generator that generates the dispersed vector by convoluting the pulse vector and the selected dispersion pattern.

Abstract: A dispersed vector generator used in an excitation vector generator for a speech coder/decoder is provided. The dispersed vector generator includes a pulse vector generating section that generates a pulse vector having a signed unit pulse on one element of a vector axis. The dispersed vector generator also includes a dispersion pattern storing section that stores a plurality of dispersion patterns, a switch that selects a dispersion pattern out of the plurality of dispersion patterns stored in the dispersion pattern storing section and a pulse vector dispersion section that generates a dispersed vector by convoluting the selected dispersion pattern and the pulse vector.

Abstract: A vector code book (1094) where representative samples of vectors to be quantized are stored is created. Each vector is made up of three elements: an AC gain, a value corresponding the logarithm of an SC gain, and an adjustment coefficient of the prediction coefficient of SC. Coefficients for predictive coding are stored in a prediction coefficient storage section (1095). The coefficients are the prediction coefficients of MA, and two kinds of coefficients, AC and SC for the order of prediction are stored. A parameter calculating section (1091) calculates a parameter necessary for distance calculation from an auditory sensation weighting input voice, an adaptive sound source subjected to auditory weighting LPC synthesis, a probabilistic sound source subjected to auditory sensation weighting LPC synthesis, a decoded vector (AC, SC, adjustment coefficient) stored in a decoded vector storage section (1096), and the prediction coefficients (AC, SC) stored in the prediction coefficient storage section (1095).

Abstract: At the speech encoding end, upon generation of an fixed excitation vector, the shape of an excitation vector output from pulse excitation codebook 301 is identified in pulse excitation vector shape identifier 302, a dispersion vector used for excitation vectors of the shape is output from dispersion vector storage 304, and, in dispersion vector convolution processor 303, dispersion vector convolution processing of the excitation vector is performed. In particular, when a pulse excitation vector having a specific shape of high frequency of use is output from pulse excitation codebook 301, pulse excitation vector shape identifier 302 controls dispersion vector storage 304 in such a way that an additional dispersion vector prepared dedicated to the pulse excitation vector is output. By this means, it is possible to provide a technology that improves the quality of decoded speech and that decodes speech more natural and audible to the user.

Abstract: A random code vector reading section and a random codebook of a conventional CELP type speech coder/decoder are respectively replaced with an oscillator for outputting different vector streams in accordance with values of input seeds, and a seed storage section for storing a plurality of seeds. This makes it unnecessary to store fixed vectors as they are in a fixed codebook (ROM), thereby considerably reducing the memory capacity.