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// -----------------------------------------------------------------------
//
// Copyright (C) 2010 Fons Adriaensen <fons@kokkinizita.net>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// -----------------------------------------------------------------------
#include <math.h>
#include "itu468detect.h"
int Itu468detect::init (int fsamp)
{
reset ();
_a1 = 670.0f / fsamp;
_b1 = 3.50f / fsamp;
_a2 = 6.60f / fsamp;
_b2 = 0.65f / fsamp;
return 0;
}
void Itu468detect::reset (void)
{
_z1 = _z2 = 0;
}
void Itu468detect::process (int n, const float *inp)
{
float x, z1, z2;
z1 = _z1;
z2 = _z2;
while (n--)
{
x = fabsf (*inp++) + 1e-30f;
z1 -= z1 * _b1;
if (x > z1) z1 += _a1 * (x - z1);
z2 -= z2 * _b2;
if (z1 > z2) z2 += _a2 * (z1 - z2);
}
_z1 = z1;
_z2 = z2;
}
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