mirror of
https://git.videolan.org/git/ffmpeg.git
synced 2024-08-01 16:59:58 +02:00
b237248e29
Instead of using fixed coefficients, the correct way is to calculate the coefficients using the highpass cutoff frequency from the ADX stream header and the sample rate.
35 lines
1.2 KiB
C
35 lines
1.2 KiB
C
/*
|
|
* 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));
|
|
}
|