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
28 enum WindowFunc { WFUNC_RECT, WFUNC_HANNING, WFUNC_HAMMING, WFUNC_BLACKMAN,
29 WFUNC_BARTLETT, WFUNC_WELCH, WFUNC_FLATTOP,
30 WFUNC_BHARRIS, WFUNC_BNUTTALL, WFUNC_SINE, WFUNC_NUTTALL,
31 WFUNC_BHANN, WFUNC_LANCZOS, WFUNC_GAUSS, WFUNC_TUKEY,
32 WFUNC_DOLPH, WFUNC_CAUCHY, WFUNC_PARZEN, WFUNC_POISSON,
33 WFUNC_BOHMAN,
34 NB_WFUNC };
35
generate_window_func(float * lut,int N,int win_func,float * overlap)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), norm = norm ? norm : sum, sum /= norm;
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 */
200