Quantizing speech signal codewords to reduce memory requirements
First Claim
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1. A method for one of coding and decoding speech signal sampled values, comprising the steps of:
- quantizing values previously obtained by an analysis from the speech signal sampled values and used for a generation of speech signal parameters before being stored in code books/code tables, the quantizing occurring to a word length that results in no noticeable losses in speech quality;
storing in the code books/code tables the values previously obtained by the analysis from the speech signal sampled values and used for the generation of speech signal parameters;
scaling the values of each code book/code table such that an available range of values is exploited as completely as possible, the step of scaling including the steps of;
determining a maximum of a positive value and a negative value of each code book/code table,if the available range of values is exceeded, performing a multiplication of the values of each code book/code table by a first factor smaller than one, andrepeating the multiplication until all elements are located in the available range of values; and
causing a number of repeated multiplications to be used as a scaling factor for all code book/code table entries, wherein for a HXVC (Harmonic Vector Excitation Coding) speech coder/speech decoder, LPC coefficients, spectral envelopes of a speech signal, and unvoiced segments of the speech signal are stored in quantized form in corresponding ones of the code books/tables.
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Abstract
For the coding or decoding of speech signal sampled values, the values contained in the code books/code tables for the generation of the speech signal parameters are stored in quantized form.
The processing can be carried out using processors with whole-number processing, without deterioration of the speech quality.
21 Citations
13 Claims
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1. A method for one of coding and decoding speech signal sampled values, comprising the steps of:
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quantizing values previously obtained by an analysis from the speech signal sampled values and used for a generation of speech signal parameters before being stored in code books/code tables, the quantizing occurring to a word length that results in no noticeable losses in speech quality; storing in the code books/code tables the values previously obtained by the analysis from the speech signal sampled values and used for the generation of speech signal parameters; scaling the values of each code book/code table such that an available range of values is exploited as completely as possible, the step of scaling including the steps of; determining a maximum of a positive value and a negative value of each code book/code table, if the available range of values is exceeded, performing a multiplication of the values of each code book/code table by a first factor smaller than one, and repeating the multiplication until all elements are located in the available range of values; and causing a number of repeated multiplications to be used as a scaling factor for all code book/code table entries, wherein for a HXVC (Harmonic Vector Excitation Coding) speech coder/speech decoder, LPC coefficients, spectral envelopes of a speech signal, and unvoiced segments of the speech signal are stored in quantized form in corresponding ones of the code books/tables. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for one of coding and decoding speech signal sampled values, comprising the steps of:
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quantizing values previously obtained by an analysis from the speech signal sampled values and used for a generation of speech signal parameters before being stored in code books/code tables, the quantizing occurring to a word length that results in no noticeable losses in speech quality; storing in the code books/code tables the values previously obtained by the analysis from the speech signal sampled values and used for the generation of speech signal parameters; scaling the values of each code book/code table such that an available range of values is exploited as completely as possible, the step of scaling including the steps of; determining a maximum of a positive value and a negative value of each code book/code table, if the available range of values is exceeded, performing a multiplication of the values of each code book/code table by a first factor smaller than one, and repeating the multiplication until all elements are located in the available range of values; and causing a number of repeated multiplications to be used as a scaling factor for all code book/code table entries, wherein; for a CELP (Code Excited Linear Prediction) speech coder/decoder, values for LSP (Line Spectral Pairs) VQ vector quantization code book/table entries, as well as those of gain VQ table entries, are stored in quantized form.
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11. An apparatus corresponding to one of a coder and a decoder for processing speech signal sampled values in accordance with a method of analysis through synthesis, comprising:
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an arrangement for storing in quantized form values contained in code books/code tables for a generation of speech signal parameters; an arrangement for selecting a word length such that no noticeable losses in speech quality occur; an arrangement for quantizing the values contained in the code books/code tables to the word length that results in no noticeable losses in speech quality; an arrangement for scaling the values of each code book/code table such that an available range of values can be exploited as completely as possible; an arrangement for determining a maximum of positive values and negative values of each code book/code table, and for multiplying the values of each code book/code table by a first factor less than one if the available range of values is exceeded; and an arrangement for, if a multiplication of the values of the code books/code tables lies outside the available range of values, performing a repeated multiplication until all elements are located in the available range of values, and for providing a number of repeated multiplications as a scaling factor. - View Dependent Claims (12, 13)
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Specification