FFmpeg
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 
35 
36 static inline void generate_window_func(float *lut, int N, int win_func,
37  float *overlap)
38 {
39  int n;
40 
41  switch (win_func) {
42  case WFUNC_RECT:
43  for (n = 0; n < N; n++)
44  lut[n] = 1.;
45  *overlap = 0.;
46  break;
47  case WFUNC_BARTLETT:
48  for (n = 0; n < N; n++)
49  lut[n] = 1.-fabs((n-(N-1)/2.)/((N-1)/2.));
50  *overlap = 0.5;
51  break;
52  case WFUNC_HANNING:
53  for (n = 0; n < N; n++)
54  lut[n] = .5*(1-cos(2*M_PI*n/(N-1)));
55  *overlap = 0.5;
56  break;
57  case WFUNC_HAMMING:
58  for (n = 0; n < N; n++)
59  lut[n] = .54-.46*cos(2*M_PI*n/(N-1));
60  *overlap = 0.5;
61  break;
62  case WFUNC_BLACKMAN:
63  for (n = 0; n < N; n++)
64  lut[n] = .42659-.49656*cos(2*M_PI*n/(N-1))+.076849*cos(4*M_PI*n/(N-1));
65  *overlap = 0.661;
66  break;
67  case WFUNC_WELCH:
68  for (n = 0; n < N; n++)
69  lut[n] = 1.-(n-(N-1)/2.)/((N-1)/2.)*(n-(N-1)/2.)/((N-1)/2.);
70  *overlap = 0.293;
71  break;
72  case WFUNC_FLATTOP:
73  for (n = 0; n < N; n++)
74  lut[n] = 1.-1.985844164102*cos( 2*M_PI*n/(N-1))+1.791176438506*cos( 4*M_PI*n/(N-1))-
75  1.282075284005*cos( 6*M_PI*n/(N-1))+0.667777530266*cos( 8*M_PI*n/(N-1))-
76  0.240160796576*cos(10*M_PI*n/(N-1))+0.056656381764*cos(12*M_PI*n/(N-1))-
77  0.008134974479*cos(14*M_PI*n/(N-1))+0.000624544650*cos(16*M_PI*n/(N-1))-
78  0.000019808998*cos(18*M_PI*n/(N-1))+0.000000132974*cos(20*M_PI*n/(N-1));
79  *overlap = 0.841;
80  break;
81  case WFUNC_BHARRIS:
82  for (n = 0; n < N; n++)
83  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));
84  *overlap = 0.661;
85  break;
86  case WFUNC_BNUTTALL:
87  for (n = 0; n < N; n++)
88  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));
89  *overlap = 0.661;
90  break;
91  case WFUNC_BHANN:
92  for (n = 0; n < N; n++)
93  lut[n] = 0.62-0.48*fabs(n/(double)(N-1)-.5)-0.38*cos(2*M_PI*n/(N-1));
94  *overlap = 0.5;
95  break;
96  case WFUNC_SINE:
97  for (n = 0; n < N; n++)
98  lut[n] = sin(M_PI*n/(N-1));
99  *overlap = 0.75;
100  break;
101  case WFUNC_NUTTALL:
102  for (n = 0; n < N; n++)
103  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));
104  *overlap = 0.663;
105  break;
106  case WFUNC_LANCZOS:
107  #define SINC(x) (!(x)) ? 1 : sin(M_PI * (x))/(M_PI * (x));
108  for (n = 0; n < N; n++)
109  lut[n] = SINC((2.*n)/(N-1)-1);
110  *overlap = 0.75;
111  break;
112  case WFUNC_GAUSS:
113  #define SQR(x) ((x)*(x))
114  for (n = 0; n < N; n++)
115  lut[n] = exp(-0.5 * SQR((n-(N-1)/2)/(0.4*(N-1)/2.f)));
116  *overlap = 0.75;
117  break;
118  case WFUNC_TUKEY:
119  for (n = 0; n < N; n++) {
120  float M = (N-1)/2.;
121 
122  if (FFABS(n - M) >= 0.3 * M) {
123  lut[n] = 0.5 * (1 + cos((M_PI*(FFABS(n - M) - 0.3 * M))/((1 - 0.3) * M)));
124  } else {
125  lut[n] = 1;
126  }
127  }
128  *overlap = 0.33;
129  break;
130  case WFUNC_DOLPH: {
131  double b = cosh(7.6009022095419887 / (N-1)), sum, t, c, norm = 0;
132  int j;
133  for (c = 1 - 1 / (b*b), n = (N-1) / 2; n >= 0; --n) {
134  for (sum = !n, b = t = j = 1; j <= n && sum != t; b *= (n-j) * (1./j), ++j)
135  t = sum, sum += (b *= c * (N - n - j) * (1./j));
136  sum /= (N - 1 - n), sum /= (norm = norm ? norm : sum);
137  lut[n] = sum;
138  lut[N - 1 - n] = sum;
139  }
140  *overlap = 0.5;}
141  break;
142  case WFUNC_CAUCHY:
143  for (n = 0; n < N; n++) {
144  double x = 2 * ((n / (double)(N - 1)) - .5);
145 
146  if (x <= -.5 || x >= .5) {
147  lut[n] = 0;
148  } else {
149  lut[n] = FFMIN(1, fabs(1/(1+4*16*x*x)));
150  }
151  }
152  *overlap = 0.75;
153  break;
154  case WFUNC_PARZEN:
155  for (n = 0; n < N; n++) {
156  double x = 2 * ((n / (double)(N - 1)) - .5);
157 
158  if (x > 0.25 && x <= 0.5) {
159  lut[n] = -2 * powf(-1 + 2 * x, 3);
160  } else if (x >= -.5 && x < -.25) {
161  lut[n] = 2 * powf(1 + 2 * x, 3);
162  } else if (x >= -.25 && x < 0) {
163  lut[n] = 1 - 24 * x * x - 48 * x * x * x;
164  } else if (x >= 0 && x <= .25) {
165  lut[n] = 1 - 24 * x * x + 48 * x * x * x;
166  } else {
167  lut[n] = 0;
168  }
169  }
170  *overlap = 0.75;
171  break;
172  case WFUNC_POISSON:
173  for (n = 0; n < N; n++) {
174  double x = 2 * ((n / (double)(N - 1)) - .5);
175 
176  if (x >= 0 && x <= .5) {
177  lut[n] = exp(-6*x);
178  } else if (x < 0 && x >= -.5) {
179  lut[n] = exp(6*x);
180  } else {
181  lut[n] = 0;
182  }
183  }
184  *overlap = 0.75;
185  break;
186  case WFUNC_BOHMAN:
187  for (n = 0; n < N; n++) {
188  double x = 2 * ((n / (double)(N - 1))) - 1.;
189 
190  lut[n] = (1 - fabs(x)) * cos(M_PI*fabs(x)) + 1./M_PI*sin(M_PI*fabs(x));
191  }
192  *overlap = 0.75;
193  break;
194  default:
195  av_assert0(0);
196  }
197 }
198 
199 #endif /* AVFILTER_WINDOW_FUNC_H */
static void generate_window_func(float *lut, int N, int win_func, float *overlap)
Definition: window_func.h:36
#define N
Definition: af_mcompand.c:54
#define SINC(x)
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
#define M(a, b)
Definition: vp3dsp.c:45
#define SQR(x)
#define f(width, name)
Definition: cbs_vp9.c:255
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
simple assert() macros that are a bit more flexible than ISO C assert().
int8_t exp
Definition: eval.c:72
#define powf(x, y)
Definition: libm.h:50
#define b
Definition: input.c:41
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:760
#define M_PI
Definition: mathematics.h:52