nest-open-source / nest-android-app / ffmpeg / 8e1cc55b733ae723de9931f20a13731bed8162f5 / . / libavfilter / window_func.c

/* | |

* 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; | |

default: | |

av_assert0(0); | |

} | |

} |