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window_func.c
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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 #include <math.h>
22 
23 #include "libavutil/avassert.h"
24 #include "window_func.h"
25 
26 void ff_generate_window_func(float *lut, int N, int win_func, float *overlap)
27 {
28  int n;
29 
30  switch (win_func) {
31  case WFUNC_RECT:
32  for (n = 0; n < N; n++)
33  lut[n] = 1.;
34  *overlap = 0.;
35  break;
36  case WFUNC_BARTLETT:
37  for (n = 0; n < N; n++)
38  lut[n] = 1.-fabs((n-(N-1)/2.)/((N-1)/2.));
39  *overlap = 0.5;
40  break;
41  case WFUNC_HANNING:
42  for (n = 0; n < N; n++)
43  lut[n] = .5*(1-cos(2*M_PI*n/(N-1)));
44  *overlap = 0.5;
45  break;
46  case WFUNC_HAMMING:
47  for (n = 0; n < N; n++)
48  lut[n] = .54-.46*cos(2*M_PI*n/(N-1));
49  *overlap = 0.5;
50  break;
51  case WFUNC_BLACKMAN:
52  for (n = 0; n < N; n++)
53  lut[n] = .42659-.49656*cos(2*M_PI*n/(N-1))+.076849*cos(4*M_PI*n/(N-1));
54  *overlap = 0.661;
55  break;
56  case WFUNC_WELCH:
57  for (n = 0; n < N; n++)
58  lut[n] = 1.-(n-(N-1)/2.)/((N-1)/2.)*(n-(N-1)/2.)/((N-1)/2.);
59  *overlap = 0.293;
60  break;
61  case WFUNC_FLATTOP:
62  for (n = 0; n < N; n++)
63  lut[n] = 1.-1.985844164102*cos( 2*M_PI*n/(N-1))+1.791176438506*cos( 4*M_PI*n/(N-1))-
64  1.282075284005*cos( 6*M_PI*n/(N-1))+0.667777530266*cos( 8*M_PI*n/(N-1))-
65  0.240160796576*cos(10*M_PI*n/(N-1))+0.056656381764*cos(12*M_PI*n/(N-1))-
66  0.008134974479*cos(14*M_PI*n/(N-1))+0.000624544650*cos(16*M_PI*n/(N-1))-
67  0.000019808998*cos(18*M_PI*n/(N-1))+0.000000132974*cos(20*M_PI*n/(N-1));
68  *overlap = 0.841;
69  break;
70  case WFUNC_BHARRIS:
71  for (n = 0; n < N; n++)
72  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));
73  *overlap = 0.661;
74  break;
75  case WFUNC_BNUTTALL:
76  for (n = 0; n < N; n++)
77  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));
78  *overlap = 0.661;
79  break;
80  case WFUNC_BHANN:
81  for (n = 0; n < N; n++)
82  lut[n] = 0.62-0.48*fabs(n/(double)(N-1)-.5)-0.38*cos(2*M_PI*n/(N-1));
83  *overlap = 0.5;
84  break;
85  case WFUNC_SINE:
86  for (n = 0; n < N; n++)
87  lut[n] = sin(M_PI*n/(N-1));
88  *overlap = 0.75;
89  break;
90  case WFUNC_NUTTALL:
91  for (n = 0; n < N; n++)
92  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));
93  *overlap = 0.663;
94  break;
95  case WFUNC_LANCZOS:
96 #define SINC(x) (!(x)) ? 1 : sin(M_PI * (x))/(M_PI * (x));
97  for (n = 0; n < N; n++)
98  lut[n] = SINC((2.*n)/(N-1)-1);
99  *overlap = 0.75;
100  break;
101  case WFUNC_GAUSS:
102 #define SQR(x) ((x)*(x))
103  for (n = 0; n < N; n++)
104  lut[n] = exp(-0.5 * SQR((n-(N-1)/2)/(0.4*(N-1)/2.f)));
105  *overlap = 0.75;
106  break;
107  case WFUNC_TUKEY:
108  for (n = 0; n < N; n++) {
109  float M = (N-1)/2.;
110 
111  if (FFABS(n - M) >= 0.3 * M) {
112  lut[n] = 0.5 * (1 + cos((M_PI*(FFABS(n - M) - 0.3 * M))/((1 - 0.3) * M)));
113  } else {
114  lut[n] = 1;
115  }
116  }
117  *overlap = 0.33;
118  break;
119  default:
120  av_assert0(0);
121  }
122 }
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
#define M(a, b)
Definition: vp3dsp.c:44
#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:64
#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:547
void ff_generate_window_func(float *lut, int N, int win_func, float *overlap)
Definition: window_func.c:26
#define SINC(x)
#define SQR(x)
#define M_PI
Definition: mathematics.h:46