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Quantizing speech signal codewords to reduce memory requirements

  • US 7,269,552 B1
  • Filed: 08/21/1999
  • Issued: 09/11/2007
  • Est. Priority Date: 10/06/1998
  • Status: Expired due to Term
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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