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/*
ITU-T G.729 Annex C - Reference C code for floating point
implementation of G.729
Version 1.01 of 15.September.98
*/
/*
----------------------------------------------------------------------
COPYRIGHT NOTICE
----------------------------------------------------------------------
ITU-T G.729 Annex C ANSI C source code
Copyright (C) 1998, AT&T, France Telecom, NTT, University of
Sherbrooke. All rights reserved.
----------------------------------------------------------------------
*/
/*
File : PRE_PROC.C
*/
/*------------------------------------------------------------------------*
* Function pre_process() *
* *
* Preprocessing of input speech. *
* - 2nd order high pass filter with cut off frequency at 140 Hz. *
*-----------------------------------------------------------------------*/
#include "typedef.h"
#include "ld8k.h"
#include "tab_ld8k.h"
/*------------------------------------------------------------------------*
* 2nd order high pass filter with cut off frequency at 140 Hz. *
* Designed with SPPACK efi command -40 dB att, 0.25 ri. *
* *
* Algorithm: *
* *
* y[i] = b[0]*x[i] + b[1]*x[i-1] + b[2]*x[i-2] *
* + a[1]*y[i-1] + a[2]*y[i-2]; *
* *
* b[3] = {0.92727435E+00, -0.18544941E+01, 0.92727435E+00}; *
* a[3] = {0.10000000E+01, 0.19059465E+01, -0.91140240E+00}; *
*-----------------------------------------------------------------------*/
static FLOAT x0, x1; /* high-pass fir memory */
static FLOAT y1, y2; /* high-pass iir memory */
void init_pre_process( void
)
{
x0 = x1 = (F)0.0;
y2 = y1 = (F)0.0;
return;
}
void pre_process(
FLOAT signal[], /* (i/o) : signal */
int lg /* (i) : lenght of signal */
)
{
int i;
FLOAT x2;
FLOAT y0;
for(i=0; i