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Methods and devices for low-frequency emphasis during audio compression based on ACELP/TCX

  • US 20070225971A1
  • Filed: 02/15/2007
  • Published: 09/27/2007
  • Est. Priority Date: 02/18/2004
  • Status: Active Grant
First Claim
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1. A method for low-frequency emphasizing the spectrum of a sound signal transformed in a frequency domain and comprising transform coefficients grouped in a number of blocks, comprising:

  • calculating a maximum energy for one block having a position index;

    calculating a factor for each block having a position index smaller than the position index of the block with maximum energy, the calculation of a factor comprising, for each block;

    computing an energy of the block; and

    computing the factor from the calculated maximum energy and the computed energy of the block; and

    for each block, determining from the factor a gain applied to the transform coefficients of the block.

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