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window_func.h
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1 /*
2  * Copyright (c) 2015 Paul B Mahol
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 
22 #ifndef AVFILTER_WINDOW_FUNC_H
23 #define AVFILTER_WINDOW_FUNC_H
24 
25 #include <math.h>
26 #include "libavutil/avassert.h"
27 
34 
35 static inline void generate_window_func(float *lut, int N, int win_func,
36  float *overlap)
37 {
38  int n;
39 
40  switch (win_func) {
41  case WFUNC_RECT:
42  for (n = 0; n < N; n++)
43  lut[n] = 1.;
44  *overlap = 0.;
45  break;
46  case WFUNC_BARTLETT:
47  for (n = 0; n < N; n++)
48  lut[n] = 1.-fabs((n-(N-1)/2.)/((N-1)/2.));
49  *overlap = 0.5;
50  break;
51  case WFUNC_HANNING:
52  for (n = 0; n < N; n++)
53  lut[n] = .5*(1-cos(2*M_PI*n/(N-1)));
54  *overlap = 0.5;
55  break;
56  case WFUNC_HAMMING:
57  for (n = 0; n < N; n++)
58  lut[n] = .54-.46*cos(2*M_PI*n/(N-1));
59  *overlap = 0.5;
60  break;
61  case WFUNC_BLACKMAN:
62  for (n = 0; n < N; n++)
63  lut[n] = .42659-.49656*cos(2*M_PI*n/(N-1))+.076849*cos(4*M_PI*n/(N-1));
64  *overlap = 0.661;
65  break;
66  case WFUNC_WELCH:
67  for (n = 0; n < N; n++)
68  lut[n] = 1.-(n-(N-1)/2.)/((N-1)/2.)*(n-(N-1)/2.)/((N-1)/2.);
69  *overlap = 0.293;
70  break;
71  case WFUNC_FLATTOP:
72  for (n = 0; n < N; n++)
73  lut[n] = 1.-1.985844164102*cos( 2*M_PI*n/(N-1))+1.791176438506*cos( 4*M_PI*n/(N-1))-
74  1.282075284005*cos( 6*M_PI*n/(N-1))+0.667777530266*cos( 8*M_PI*n/(N-1))-
75  0.240160796576*cos(10*M_PI*n/(N-1))+0.056656381764*cos(12*M_PI*n/(N-1))-
76  0.008134974479*cos(14*M_PI*n/(N-1))+0.000624544650*cos(16*M_PI*n/(N-1))-
77  0.000019808998*cos(18*M_PI*n/(N-1))+0.000000132974*cos(20*M_PI*n/(N-1));
78  *overlap = 0.841;
79  break;
80  case WFUNC_BHARRIS:
81  for (n = 0; n < N; n++)
82  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));
83  *overlap = 0.661;
84  break;
85  case WFUNC_BNUTTALL:
86  for (n = 0; n < N; n++)
87  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));
88  *overlap = 0.661;
89  break;
90  case WFUNC_BHANN:
91  for (n = 0; n < N; n++)
92  lut[n] = 0.62-0.48*fabs(n/(double)(N-1)-.5)-0.38*cos(2*M_PI*n/(N-1));
93  *overlap = 0.5;
94  break;
95  case WFUNC_SINE:
96  for (n = 0; n < N; n++)
97  lut[n] = sin(M_PI*n/(N-1));
98  *overlap = 0.75;
99  break;
100  case WFUNC_NUTTALL:
101  for (n = 0; n < N; n++)
102  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));
103  *overlap = 0.663;
104  break;
105  case WFUNC_LANCZOS:
106  #define SINC(x) (!(x)) ? 1 : sin(M_PI * (x))/(M_PI * (x));
107  for (n = 0; n < N; n++)
108  lut[n] = SINC((2.*n)/(N-1)-1);
109  *overlap = 0.75;
110  break;
111  case WFUNC_GAUSS:
112  #define SQR(x) ((x)*(x))
113  for (n = 0; n < N; n++)
114  lut[n] = exp(-0.5 * SQR((n-(N-1)/2)/(0.4*(N-1)/2.f)));
115  *overlap = 0.75;
116  break;
117  case WFUNC_TUKEY:
118  for (n = 0; n < N; n++) {
119  float M = (N-1)/2.;
120 
121  if (FFABS(n - M) >= 0.3 * M) {
122  lut[n] = 0.5 * (1 + cos((M_PI*(FFABS(n - M) - 0.3 * M))/((1 - 0.3) * M)));
123  } else {
124  lut[n] = 1;
125  }
126  }
127  *overlap = 0.33;
128  break;
129  case WFUNC_DOLPH: {
130  double b = cosh(7.6009022095419887 / (N-1)), sum, t, c, norm = 0;
131  int j;
132  for (c = 1 - 1 / (b*b), n = (N-1) / 2; n >= 0; --n) {
133  for (sum = !n, b = t = j = 1; j <= n && sum != t; b *= (n-j) * (1./j), ++j)
134  t = sum, sum += (b *= c * (N - n - j) * (1./j));
135  sum /= (N - 1 - n), sum /= (norm = norm ? norm : sum);
136  lut[n] = sum;
137  lut[N - 1 - n] = sum;
138  }
139  *overlap = 0.5;}
140  break;
141  case WFUNC_CAUCHY:
142  for (n = 0; n < N; n++) {
143  double x = 2 * ((n / (double)(N - 1)) - .5);
144 
145  if (x <= -.5 || x >= .5) {
146  lut[n] = 0;
147  } else {
148  lut[n] = FFMIN(1, fabs(1/(1+4*16*x*x)));
149  }
150  }
151  *overlap = 0.75;
152  break;
153  case WFUNC_PARZEN:
154  for (n = 0; n < N; n++) {
155  double x = 2 * ((n / (double)(N - 1)) - .5);
156 
157  if (x > 0.25 && x <= 0.5) {
158  lut[n] = -2 * powf(-1 + 2 * x, 3);
159  } else if (x >= -.5 && x < -.25) {
160  lut[n] = 2 * powf(1 + 2 * x, 3);
161  } else if (x >= -.25 && x < 0) {
162  lut[n] = 1 - 24 * x * x - 48 * x * x * x;
163  } else if (x >= 0 && x <= .25) {
164  lut[n] = 1 - 24 * x * x + 48 * x * x * x;
165  } else {
166  lut[n] = 0;
167  }
168  }
169  *overlap = 0.75;
170  break;
171  case WFUNC_POISSON:
172  for (n = 0; n < N; n++) {
173  double x = 2 * ((n / (double)(N - 1)) - .5);
174 
175  if (x >= 0 && x <= .5) {
176  lut[n] = exp(-6*x);
177  } else if (x < 0 && x >= -.5) {
178  lut[n] = exp(6*x);
179  } else {
180  lut[n] = 0;
181  }
182  }
183  *overlap = 0.75;
184  break;
185  default:
186  av_assert0(0);
187  }
188 }
189 
190 #endif /* AVFILTER_WINDOW_FUNC_H */
const char * b
Definition: vf_curves.c:113
static void generate_window_func(float *lut, int N, int win_func, float *overlap)
Definition: window_func.h:35
#define SINC(x)
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
#define M(a, b)
Definition: vp3dsp.c:44
#define SQR(x)
#define N
Definition: vf_pp7.c:73
simple assert() macros that are a bit more flexible than ISO C assert().
int8_t exp
Definition: eval.c:65
#define powf(x, y)
Definition: libm.h:50
WindowFunc
#define FFMIN(a, b)
Definition: common.h:96
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:72
int n
Definition: avisynth_c.h:684
static double c[64]
#define M_PI
Definition: mathematics.h:52