摘要:
A stochastic codebook 103 associates a pulse position of a predetermined channel with a pulse position of another channel, searches for a pulse position by means of a predetermined algorithm, and outputs a code combining a found pulse position with a polarity code to an excitation vector creation section 104 as a stochastic excitation vector code. By this means, it is possible to secure variations so that there are no positions where there is no pulse at all while achieving a reduction of the number of bits used when coding stochastic codebook pulses in order to attain a lower bit rate.
摘要:
In a CELP type speech coder, the excitation is quantized by vectors from a random codebook. The random codebook is made of a fixed waveform storage section (181), followed by a vector rearranging unit (182). The rearranging section (182) shifts the vectors to positions determined to minimize the quantization distorsion using a pulse placement methodology of an algebraic coder. The vectors are summed (183) to generate the excitation code vector.
摘要:
The present invention intends to enhance a sound quality of a sound source generating portion in a CELP type voice encoding device and a CELP type voice decoding device. A pitch peak position of an adaptive code vector is obtained by a pitch peak position calculator, a window for emphasizing an amplitude of the pitch peak position is prepared by an amplitude emphasizing window generator (13), and an amplitude of a noise code vector corresponding to the pitch peak position is emphasized by an amplitude emphasizing window unit (16).
摘要:
An excitation vector generator comprises a pulse vector generating section having N channels (N≧1) for generating pulse vectors, a storing section for storing M (M≧1)kinds of dispersion patterns every channel in accordance with N channels, a selecting section for selectively taking out a dispersion pattern from the storing section every channel, a dispersion section for performing a superimposing calculation of the extracted dispersion pattern and the generated pulse vectors every channel so as to generate N dispersion vectors, excitation vector generating section for generating an excitation vector from N dispersion vectors generated.
摘要:
A speech coding method and a speech coder operating according to the code excited linear prediction paradigm. A random codevector is chosen using an orthogonalization search. Said search determines an optimum random excitation gain minimizing a distortion function. The denominator of the gain function is determined using preprocessed matrices determined in advance and depending on the adaptive codevector and synthesis filter matrix in order to reduce the amount of filtering operations during the search of the random codebook.
摘要:
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. A Comparison Judge Section (CJS) 110 restricts the number of times fractional-accuracy pitch information is selected in an optimal pitch cycle.
摘要:
A vector codebook 1094 storing a plurality of typical samples of quantization target vectors is created. Each vector consists of three elements, which are values corresponding to logarithmic values of an AC gain and SC gain and an adjustment coefficient of SC prediction coefficient. Prediction coefficient storage section 1095 stores coefficients to perform predictive coding. These coefficients are MA prediction coefficients and a number of coefficients corresponding to the degree of prediction, of two types, AC and SC, are stored. Parameter calculation section 1091 calculates parameters necessary for distance calculations from the input perceptual weighted input speech, perceptual weighted LPC synthesis of adaptive code vector, perceptual weighted LPC synthesis of stochastic code vector, further decoded vectors (AC, SC, adjustment coefficient) stored in decoded vector storage section 1096 and prediction coefficients (AC, SC) stored in prediction coefficient storage section 1095.
摘要:
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. A Comparison Judge Section (CJS) 110 restricts the number of times fractional-accuracy pitch information is selected in an optimal pitch cycle.
摘要:
In a CELP type speech coder, the excitation is quantized by vectors from a random codebook. The random codebook is made of a fixed waveform storage section (181), followed by a vector rearranging unit (182). The rearranging section (182) shifts the vectors to positions determined to minimize the quantization distorsion using a pulse placement methodology of an algebraic coder. The vectors are summed (183) to generate the excitation code vector.
摘要:
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.