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Diffstat (limited to 'libavfilter/window_func.h')
| -rw-r--r-- | libavfilter/window_func.h | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/libavfilter/window_func.h b/libavfilter/window_func.h new file mode 100644 index 0000000000..a94482c937 --- /dev/null +++ b/libavfilter/window_func.h @@ -0,0 +1,190 @@ +/* + * 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 + */ + + +#ifndef AVFILTER_WINDOW_FUNC_H +#define AVFILTER_WINDOW_FUNC_H + +#include <math.h> +#include "libavutil/avassert.h" + +enum WindowFunc { WFUNC_RECT, WFUNC_HANNING, WFUNC_HAMMING, WFUNC_BLACKMAN, + WFUNC_BARTLETT, WFUNC_WELCH, WFUNC_FLATTOP, + WFUNC_BHARRIS, WFUNC_BNUTTALL, WFUNC_SINE, WFUNC_NUTTALL, + WFUNC_BHANN, WFUNC_LANCZOS, WFUNC_GAUSS, WFUNC_TUKEY, + WFUNC_DOLPH, WFUNC_CAUCHY, WFUNC_PARZEN, WFUNC_POISSON, + NB_WFUNC }; + +static inline void 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(7.6009022095419887 / (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; + case WFUNC_CAUCHY: + for (n = 0; n < N; n++) { + double x = 2 * ((n / (double)(N - 1)) - .5); + + if (x <= -.5 || x >= .5) { + lut[n] = 0; + } else { + lut[n] = FFMIN(1, fabs(1/(1+4*16*x*x))); + } + } + *overlap = 0.75; + break; + case WFUNC_PARZEN: + for (n = 0; n < N; n++) { + double x = 2 * ((n / (double)(N - 1)) - .5); + + if (x > 0.25 && x <= 0.5) { + lut[n] = -2 * powf(-1 + 2 * x, 3); + } else if (x >= -.5 && x < -.25) { + lut[n] = 2 * powf(1 + 2 * x, 3); + } else if (x >= -.25 && x < 0) { + lut[n] = 1 - 24 * x * x - 48 * x * x * x; + } else if (x >= 0 && x <= .25) { + lut[n] = 1 - 24 * x * x + 48 * x * x * x; + } else { + lut[n] = 0; + } + } + *overlap = 0.75; + break; + case WFUNC_POISSON: + for (n = 0; n < N; n++) { + double x = 2 * ((n / (double)(N - 1)) - .5); + + if (x >= 0 && x <= .5) { + lut[n] = exp(-6*x); + } else if (x < 0 && x >= -.5) { + lut[n] = exp(6*x); + } else { + lut[n] = 0; + } + } + *overlap = 0.75; + break; + default: + av_assert0(0); + } +} + +#endif /* AVFILTER_WINDOW_FUNC_H */ |