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/*
* Copyright (c) 2015 Paul B Mahol
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <math.h>
#include "libavutil/avassert.h"
#include "window_func.h"
void ff_generate_window_func(float *lut, int N, int win_func, float *overlap)
{
int n;
switch (win_func) {
case WFUNC_RECT:
for (n = 0; n < N; n++)
lut[n] = 1.;
*overlap = 0.;
break;
case WFUNC_BARTLETT:
for (n = 0; n < N; n++)
lut[n] = 1.-fabs((n-(N-1)/2.)/((N-1)/2.));
*overlap = 0.5;
break;
case WFUNC_HANNING:
for (n = 0; n < N; n++)
lut[n] = .5*(1-cos(2*M_PI*n/(N-1)));
*overlap = 0.5;
break;
case WFUNC_HAMMING:
for (n = 0; n < N; n++)
lut[n] = .54-.46*cos(2*M_PI*n/(N-1));
*overlap = 0.5;
break;
case WFUNC_BLACKMAN:
for (n = 0; n < N; n++)
lut[n] = .42659-.49656*cos(2*M_PI*n/(N-1))+.076849*cos(4*M_PI*n/(N-1));
*overlap = 0.661;
break;
case WFUNC_WELCH:
for (n = 0; n < N; n++)
lut[n] = 1.-(n-(N-1)/2.)/((N-1)/2.)*(n-(N-1)/2.)/((N-1)/2.);
*overlap = 0.293;
break;
case WFUNC_FLATTOP:
for (n = 0; n < N; n++)
lut[n] = 1.-1.985844164102*cos( 2*M_PI*n/(N-1))+1.791176438506*cos( 4*M_PI*n/(N-1))-
1.282075284005*cos( 6*M_PI*n/(N-1))+0.667777530266*cos( 8*M_PI*n/(N-1))-
0.240160796576*cos(10*M_PI*n/(N-1))+0.056656381764*cos(12*M_PI*n/(N-1))-
0.008134974479*cos(14*M_PI*n/(N-1))+0.000624544650*cos(16*M_PI*n/(N-1))-
0.000019808998*cos(18*M_PI*n/(N-1))+0.000000132974*cos(20*M_PI*n/(N-1));
*overlap = 0.841;
break;
case WFUNC_BHARRIS:
for (n = 0; n < N; n++)
lut[n] = 0.35875-0.48829*cos(2*M_PI*n/(N-1))+0.14128*cos(4*M_PI*n/(N-1))-0.01168*cos(6*M_PI*n/(N-1));
*overlap = 0.661;
break;
case WFUNC_BNUTTALL:
for (n = 0; n < N; n++)
lut[n] = 0.3635819-0.4891775*cos(2*M_PI*n/(N-1))+0.1365995*cos(4*M_PI*n/(N-1))-0.0106411*cos(6*M_PI*n/(N-1));
*overlap = 0.661;
break;
case WFUNC_BHANN:
for (n = 0; n < N; n++)
lut[n] = 0.62-0.48*fabs(n/(double)(N-1)-.5)-0.38*cos(2*M_PI*n/(N-1));
*overlap = 0.5;
break;
case WFUNC_SINE:
for (n = 0; n < N; n++)
lut[n] = sin(M_PI*n/(N-1));
*overlap = 0.75;
break;
case WFUNC_NUTTALL:
for (n = 0; n < N; n++)
lut[n] = 0.355768-0.487396*cos(2*M_PI*n/(N-1))+0.144232*cos(4*M_PI*n/(N-1))-0.012604*cos(6*M_PI*n/(N-1));
*overlap = 0.663;
break;
case WFUNC_LANCZOS:
#define SINC(x) (!(x)) ? 1 : sin(M_PI * (x))/(M_PI * (x));
for (n = 0; n < N; n++)
lut[n] = SINC((2.*n)/(N-1)-1);
*overlap = 0.75;
break;
case WFUNC_GAUSS:
#define SQR(x) ((x)*(x))
for (n = 0; n < N; n++)
lut[n] = exp(-0.5 * SQR((n-(N-1)/2)/(0.4*(N-1)/2.f)));
*overlap = 0.75;
break;
case WFUNC_TUKEY:
for (n = 0; n < N; n++) {
float M = (N-1)/2.;
if (FFABS(n - M) >= 0.3 * M) {
lut[n] = 0.5 * (1 + cos((M_PI*(FFABS(n - M) - 0.3 * M))/((1 - 0.3) * M)));
} else {
lut[n] = 1;
}
}
*overlap = 0.33;
break;
case WFUNC_DOLPH: {
double b = cosh(acosh(pow(10., 3)) / (N-1)), sum, t, c, norm = 0;
int j;
for (c = 1 - 1 / (b*b), n = (N-1) / 2; n >= 0; --n) {
for (sum = !n, b = t = j = 1; j <= n && sum != t; b *= (n-j) * (1./j), ++j)
t = sum, sum += (b *= c * (N - n - j) * (1./j));
sum /= (N - 1 - n), sum /= (norm = norm ? norm : sum);
lut[n] = sum;
lut[N - 1 - n] = sum;
}
*overlap = 0.5;}
break;
default:
av_assert0(0);
}
}
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