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The initial filter states are set to zero.
3.B.8 CELP weighting module
3.B.8.1 Tool description
The CELP weighting module computes the weights to be applied on the LPC coefficients.
3.B.8.2 Definitions
Input
lpc_coefficients[]: This is an array of dimension lpc_order, containing the LPC Coefficients.
gamma_num: This field contains the weighting factor of the numerator.
gamma_den: This field contains the weighting factor of the denominator.
Output
ISO/IEC 14496-3:2005(E)
Wnum_coeff[]: This is an array of dimension Wnum_order, containing the weighted numerator coefficients.
Wden_coeff[]: This array has dimension Wden_order and contains the weighted denominator coefficients.
Configuration
lpc_order: This field contains the order of the LPC.
3.B.8.3 Encoding process
The weighted coefficients of the numerator are computed by:
for (k = 0; k < Wnum_order; k++)
{
Wnum_coeff[k] = lpc_coefficients[k] * gamma_num k+1 ;
}
The weighted coefficients of the denominator are computed by:
for (k = 0; k < Wden_order; k++)
{
Wden_coeff[k] = lpc_coefficients[k] * gamma_den k+1 ;
}
3.B.9 CELP excitation analysis
The CELP excitation analysis computes the shape and gain vectors as well as the decoded synthesized speech
signal. For excitation analysis modules, Regular Pulse Excitation (RPE) and Multi Pulse Excitation (MPE) are
defined.
© ISO/IEC 2005 — All rights reserved 105