FFmpeg/libavfilter/window_func.h

/*
 * 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"
#include "libavutil/common.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,
                      WFUNC_BOHMAN, WFUNC_KAISER,
                      NB_WFUNC };

#define WIN_FUNC_OPTION(win_func_opt_name, win_func_offset, flag, default_window_func)                              \
    { win_func_opt_name, "set window function", win_func_offset, AV_OPT_TYPE_INT, {.i64 = default_window_func}, 0, NB_WFUNC-1, flag, "win_func" }, \
        { "rect",     "Rectangular",      0, AV_OPT_TYPE_CONST, {.i64=WFUNC_RECT},     0, 0, flag, "win_func" }, \
        { "bartlett", "Bartlett",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BARTLETT}, 0, 0, flag, "win_func" }, \
        { "hann",     "Hann",             0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING},  0, 0, flag, "win_func" }, \
        { "hanning",  "Hanning",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HANNING},  0, 0, flag, "win_func" }, \
        { "hamming",  "Hamming",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_HAMMING},  0, 0, flag, "win_func" }, \
        { "blackman", "Blackman",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BLACKMAN}, 0, 0, flag, "win_func" }, \
        { "welch",    "Welch",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_WELCH},    0, 0, flag, "win_func" }, \
        { "flattop",  "Flat-top",         0, AV_OPT_TYPE_CONST, {.i64=WFUNC_FLATTOP},  0, 0, flag, "win_func" }, \
        { "bharris",  "Blackman-Harris",  0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHARRIS},  0, 0, flag, "win_func" }, \
        { "bnuttall", "Blackman-Nuttall", 0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BNUTTALL}, 0, 0, flag, "win_func" }, \
        { "bhann",    "Bartlett-Hann",    0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BHANN},    0, 0, flag, "win_func" }, \
        { "sine",     "Sine",             0, AV_OPT_TYPE_CONST, {.i64=WFUNC_SINE},     0, 0, flag, "win_func" }, \
        { "nuttall",  "Nuttall",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_NUTTALL},  0, 0, flag, "win_func" }, \
        { "lanczos",  "Lanczos",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_LANCZOS},  0, 0, flag, "win_func" }, \
        { "gauss",    "Gauss",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_GAUSS},    0, 0, flag, "win_func" }, \
        { "tukey",    "Tukey",            0, AV_OPT_TYPE_CONST, {.i64=WFUNC_TUKEY},    0, 0, flag, "win_func" }, \
        { "dolph",    "Dolph-Chebyshev",  0, AV_OPT_TYPE_CONST, {.i64=WFUNC_DOLPH},    0, 0, flag, "win_func" }, \
        { "cauchy",   "Cauchy",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_CAUCHY},   0, 0, flag, "win_func" }, \
        { "parzen",   "Parzen",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_PARZEN},   0, 0, flag, "win_func" }, \
        { "poisson",  "Poisson",          0, AV_OPT_TYPE_CONST, {.i64=WFUNC_POISSON},  0, 0, flag, "win_func" }, \
        { "bohman",   "Bohman",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_BOHMAN},   0, 0, flag, "win_func" }, \
        { "kaiser",   "Kaiser",           0, AV_OPT_TYPE_CONST, {.i64=WFUNC_KAISER},   0, 0, flag, "win_func" }

static inline double get_i0(double x)
{
    double y = 1.0, prev = 1.0, i = 1.0;

    while (fabs(prev) > 1e-20) {
        double summand = prev * x * x / (4 * i * i);
        y += summand;
        prev = summand;
        i++;
    }

    return y;
}

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), norm = norm ? norm : sum, sum /= norm;
            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;
    case WFUNC_BOHMAN:
        for (n = 0; n < N; n++) {
            double x = 2 * ((n / (double)(N - 1))) - 1.;

            lut[n] = (1 - fabs(x)) * cos(M_PI*fabs(x)) + 1./M_PI*sin(M_PI*fabs(x));
        }
        *overlap = 0.75;
        break;
    case WFUNC_KAISER:
        for (n = 0; n < N; n++) {
            double x = 2.0 / (double)(N - 1);

            lut[n] = get_i0(12. * sqrt(1. - SQR(n * x - 1.))) / get_i0(12.);
        }
        *overlap = 0.75;
        break;
    default:
        av_assert0(0);
    }
}

#endif /* AVFILTER_WINDOW_FUNC_H */