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/*
* Copyright (c) 2011 Justin Ruggles
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/mathematics.h"
#include "adx.h"
void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff)
{
double a, b, c;
a = M_SQRT2 - cos(2.0 * M_PI * cutoff / sample_rate);
b = M_SQRT2 - 1.0;
c = (a - sqrt((a + b) * (a - b))) / b;
coeff[0] = lrintf(c * 2.0 * (1 << bits));
coeff[1] = lrintf(-(c * c) * (1 << bits));
}
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