text: /*
   * 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,
                        WFUNC_BOHMAN,
                        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" }
  
  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;
      default:
          av_assert0(0);
      }
  }
  
  #endif /* AVFILTER_WINDOW_FUNC_H */
  