mirror of
https://github.com/FFmpeg/FFmpeg.git
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111 lines
3.8 KiB
C
111 lines
3.8 KiB
C
/*
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* Copyright (c) 2015 Paul B Mahol
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <math.h>
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#include "libavutil/avassert.h"
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#include "window_func.h"
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void ff_generate_window_func(float *lut, int N, int win_func, float *overlap)
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{
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int n;
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switch (win_func) {
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case WFUNC_RECT:
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for (n = 0; n < N; n++)
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lut[n] = 1.;
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*overlap = 0.;
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break;
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case WFUNC_BARTLETT:
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for (n = 0; n < N; n++)
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lut[n] = 1.-fabs((n-(N-1)/2.)/((N-1)/2.));
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*overlap = 0.5;
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break;
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case WFUNC_HANNING:
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for (n = 0; n < N; n++)
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lut[n] = .5*(1-cos(2*M_PI*n/(N-1)));
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*overlap = 0.5;
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break;
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case WFUNC_HAMMING:
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for (n = 0; n < N; n++)
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lut[n] = .54-.46*cos(2*M_PI*n/(N-1));
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*overlap = 0.5;
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break;
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case WFUNC_BLACKMAN:
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for (n = 0; n < N; n++)
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lut[n] = .42659-.49656*cos(2*M_PI*n/(N-1))+.076849*cos(4*M_PI*n/(N-1));
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*overlap = 0.661;
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break;
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case WFUNC_WELCH:
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for (n = 0; n < N; n++)
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lut[n] = 1.-(n-(N-1)/2.)/((N-1)/2.)*(n-(N-1)/2.)/((N-1)/2.);
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*overlap = 0.293;
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break;
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case WFUNC_FLATTOP:
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for (n = 0; n < N; n++)
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lut[n] = 1.-1.985844164102*cos( 2*M_PI*n/(N-1))+1.791176438506*cos( 4*M_PI*n/(N-1))-
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1.282075284005*cos( 6*M_PI*n/(N-1))+0.667777530266*cos( 8*M_PI*n/(N-1))-
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0.240160796576*cos(10*M_PI*n/(N-1))+0.056656381764*cos(12*M_PI*n/(N-1))-
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0.008134974479*cos(14*M_PI*n/(N-1))+0.000624544650*cos(16*M_PI*n/(N-1))-
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0.000019808998*cos(18*M_PI*n/(N-1))+0.000000132974*cos(20*M_PI*n/(N-1));
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*overlap = 0.841;
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break;
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case WFUNC_BHARRIS:
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for (n = 0; n < N; n++)
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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));
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*overlap = 0.661;
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break;
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case WFUNC_BNUTTALL:
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for (n = 0; n < N; n++)
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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));
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*overlap = 0.661;
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break;
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case WFUNC_BHANN:
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for (n = 0; n < N; n++)
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lut[n] = 0.62-0.48*fabs(n/(double)(N-1)-.5)-0.38*cos(2*M_PI*n/(N-1));
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*overlap = 0.5;
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break;
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case WFUNC_SINE:
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for (n = 0; n < N; n++)
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lut[n] = sin(M_PI*n/(N-1));
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*overlap = 0.75;
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break;
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case WFUNC_NUTTALL:
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for (n = 0; n < N; n++)
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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));
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*overlap = 0.663;
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break;
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case WFUNC_LANCZOS:
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#define SINC(x) (!(x)) ? 1 : sin(M_PI * (x))/(M_PI * (x));
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for (n = 0; n < N; n++)
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lut[n] = SINC((2.*n)/(N-1)-1);
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*overlap = 0.75;
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break;
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case WFUNC_GAUSS:
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#define SQR(x) ((x)*(x))
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for (n = 0; n < N; n++)
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lut[n] = exp(-0.5 * SQR((n-(N-1)/2)/(0.4*(N-1)/2.f)));
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*overlap = 0.75;
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break;
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default:
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av_assert0(0);
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}
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}
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