diff options
Diffstat (limited to 'libavfilter/window_func.c')
-rw-r--r-- | libavfilter/window_func.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/libavfilter/window_func.c b/libavfilter/window_func.c new file mode 100644 index 0000000000..15600beebb --- /dev/null +++ b/libavfilter/window_func.c @@ -0,0 +1,110 @@ +/* + * 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; + default: + av_assert0(0); + } +} |