1 /* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2006-2009 Josh Coalson
3 * Copyright (C) 2011-2013 Xiph.Org Foundation
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * - Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * - Neither the name of the Xiph.org Foundation nor the names of its
17 * contributors may be used to endorse or promote products derived from
18 * this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
24 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
26 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
27 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
28 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
29 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
30 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #ifdef HAVE_CONFIG_H
34 # include <config.h>
35 #endif
36
37 #include <math.h>
38 #include "share/compat.h"
39 #include "FLAC/assert.h"
40 #include "FLAC/format.h"
41 #include "private/window.h"
42
43 #ifndef FLAC__INTEGER_ONLY_LIBRARY
44
45
FLAC__window_bartlett(FLAC__real * window,const FLAC__int32 L)46 void FLAC__window_bartlett(FLAC__real *window, const FLAC__int32 L)
47 {
48 const FLAC__int32 N = L - 1;
49 FLAC__int32 n;
50
51 if (L & 1) {
52 for (n = 0; n <= N/2; n++)
53 window[n] = 2.0f * n / (float)N;
54 for (; n <= N; n++)
55 window[n] = 2.0f - 2.0f * n / (float)N;
56 }
57 else {
58 for (n = 0; n <= L/2-1; n++)
59 window[n] = 2.0f * n / (float)N;
60 for (; n <= N; n++)
61 window[n] = 2.0f - 2.0f * (N-n) / (float)N;
62 }
63 }
64
FLAC__window_bartlett_hann(FLAC__real * window,const FLAC__int32 L)65 void FLAC__window_bartlett_hann(FLAC__real *window, const FLAC__int32 L)
66 {
67 const FLAC__int32 N = L - 1;
68 FLAC__int32 n;
69
70 for (n = 0; n < L; n++)
71 window[n] = (FLAC__real)(0.62f - 0.48f * fabs((float)n/(float)N+0.5f) + 0.38f * cos(2.0f * M_PI * ((float)n/(float)N+0.5f)));
72 }
73
FLAC__window_blackman(FLAC__real * window,const FLAC__int32 L)74 void FLAC__window_blackman(FLAC__real *window, const FLAC__int32 L)
75 {
76 const FLAC__int32 N = L - 1;
77 FLAC__int32 n;
78
79 for (n = 0; n < L; n++)
80 window[n] = (FLAC__real)(0.42f - 0.5f * cos(2.0f * M_PI * n / N) + 0.08f * cos(4.0f * M_PI * n / N));
81 }
82
83 /* 4-term -92dB side-lobe */
FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real * window,const FLAC__int32 L)84 void FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real *window, const FLAC__int32 L)
85 {
86 const FLAC__int32 N = L - 1;
87 FLAC__int32 n;
88
89 for (n = 0; n <= N; n++)
90 window[n] = (FLAC__real)(0.35875f - 0.48829f * cos(2.0f * M_PI * n / N) + 0.14128f * cos(4.0f * M_PI * n / N) - 0.01168f * cos(6.0f * M_PI * n / N));
91 }
92
FLAC__window_connes(FLAC__real * window,const FLAC__int32 L)93 void FLAC__window_connes(FLAC__real *window, const FLAC__int32 L)
94 {
95 const FLAC__int32 N = L - 1;
96 const double N2 = (double)N / 2.;
97 FLAC__int32 n;
98
99 for (n = 0; n <= N; n++) {
100 double k = ((double)n - N2) / N2;
101 k = 1.0f - k * k;
102 window[n] = (FLAC__real)(k * k);
103 }
104 }
105
FLAC__window_flattop(FLAC__real * window,const FLAC__int32 L)106 void FLAC__window_flattop(FLAC__real *window, const FLAC__int32 L)
107 {
108 const FLAC__int32 N = L - 1;
109 FLAC__int32 n;
110
111 for (n = 0; n < L; n++)
112 window[n] = (FLAC__real)(1.0f - 1.93f * cos(2.0f * M_PI * n / N) + 1.29f * cos(4.0f * M_PI * n / N) - 0.388f * cos(6.0f * M_PI * n / N) + 0.0322f * cos(8.0f * M_PI * n / N));
113 }
114
FLAC__window_gauss(FLAC__real * window,const FLAC__int32 L,const FLAC__real stddev)115 void FLAC__window_gauss(FLAC__real *window, const FLAC__int32 L, const FLAC__real stddev)
116 {
117 const FLAC__int32 N = L - 1;
118 const double N2 = (double)N / 2.;
119 FLAC__int32 n;
120
121 for (n = 0; n <= N; n++) {
122 const double k = ((double)n - N2) / (stddev * N2);
123 window[n] = (FLAC__real)exp(-0.5f * k * k);
124 }
125 }
126
FLAC__window_hamming(FLAC__real * window,const FLAC__int32 L)127 void FLAC__window_hamming(FLAC__real *window, const FLAC__int32 L)
128 {
129 const FLAC__int32 N = L - 1;
130 FLAC__int32 n;
131
132 for (n = 0; n < L; n++)
133 window[n] = (FLAC__real)(0.54f - 0.46f * cos(2.0f * M_PI * n / N));
134 }
135
FLAC__window_hann(FLAC__real * window,const FLAC__int32 L)136 void FLAC__window_hann(FLAC__real *window, const FLAC__int32 L)
137 {
138 const FLAC__int32 N = L - 1;
139 FLAC__int32 n;
140
141 for (n = 0; n < L; n++)
142 window[n] = (FLAC__real)(0.5f - 0.5f * cos(2.0f * M_PI * n / N));
143 }
144
FLAC__window_kaiser_bessel(FLAC__real * window,const FLAC__int32 L)145 void FLAC__window_kaiser_bessel(FLAC__real *window, const FLAC__int32 L)
146 {
147 const FLAC__int32 N = L - 1;
148 FLAC__int32 n;
149
150 for (n = 0; n < L; n++)
151 window[n] = (FLAC__real)(0.402f - 0.498f * cos(2.0f * M_PI * n / N) + 0.098f * cos(4.0f * M_PI * n / N) - 0.001f * cos(6.0f * M_PI * n / N));
152 }
153
FLAC__window_nuttall(FLAC__real * window,const FLAC__int32 L)154 void FLAC__window_nuttall(FLAC__real *window, const FLAC__int32 L)
155 {
156 const FLAC__int32 N = L - 1;
157 FLAC__int32 n;
158
159 for (n = 0; n < L; n++)
160 window[n] = (FLAC__real)(0.3635819f - 0.4891775f*cos(2.0f*M_PI*n/N) + 0.1365995f*cos(4.0f*M_PI*n/N) - 0.0106411f*cos(6.0f*M_PI*n/N));
161 }
162
FLAC__window_rectangle(FLAC__real * window,const FLAC__int32 L)163 void FLAC__window_rectangle(FLAC__real *window, const FLAC__int32 L)
164 {
165 FLAC__int32 n;
166
167 for (n = 0; n < L; n++)
168 window[n] = 1.0f;
169 }
170
FLAC__window_triangle(FLAC__real * window,const FLAC__int32 L)171 void FLAC__window_triangle(FLAC__real *window, const FLAC__int32 L)
172 {
173 FLAC__int32 n;
174
175 if (L & 1) {
176 for (n = 1; n <= L+1/2; n++)
177 window[n-1] = 2.0f * n / ((float)L + 1.0f);
178 for (; n <= L; n++)
179 window[n-1] = - (float)(2 * (L - n + 1)) / ((float)L + 1.0f);
180 }
181 else {
182 for (n = 1; n <= L/2; n++)
183 window[n-1] = 2.0f * n / (float)L;
184 for (; n <= L; n++)
185 window[n-1] = ((float)(2 * (L - n)) + 1.0f) / (float)L;
186 }
187 }
188
FLAC__window_tukey(FLAC__real * window,const FLAC__int32 L,const FLAC__real p)189 void FLAC__window_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p)
190 {
191 if (p <= 0.0)
192 FLAC__window_rectangle(window, L);
193 else if (p >= 1.0)
194 FLAC__window_hann(window, L);
195 else {
196 const FLAC__int32 Np = (FLAC__int32)(p / 2.0f * L) - 1;
197 FLAC__int32 n;
198 /* start with rectangle... */
199 FLAC__window_rectangle(window, L);
200 /* ...replace ends with hann */
201 if (Np > 0) {
202 for (n = 0; n <= Np; n++) {
203 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * n / Np));
204 window[L-Np-1+n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * (n+Np) / Np));
205 }
206 }
207 }
208 }
209
FLAC__window_welch(FLAC__real * window,const FLAC__int32 L)210 void FLAC__window_welch(FLAC__real *window, const FLAC__int32 L)
211 {
212 const FLAC__int32 N = L - 1;
213 const double N2 = (double)N / 2.;
214 FLAC__int32 n;
215
216 for (n = 0; n <= N; n++) {
217 const double k = ((double)n - N2) / N2;
218 window[n] = (FLAC__real)(1.0f - k * k);
219 }
220 }
221
222 #endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */
223