1 /* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2006-2009 Josh Coalson
3 * Copyright (C) 2011-2016 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 #include <math.h>
34 #include "share/compat.h"
35 #include "FLAC/format.h"
36 #include "private/window.h"
37
FLAC__window_bartlett(FLAC__real * window,const FLAC__int32 L)38 void FLAC__window_bartlett(FLAC__real *window, const FLAC__int32 L)
39 {
40 const FLAC__int32 N = L - 1;
41 FLAC__int32 n;
42
43 if (L & 1) {
44 for (n = 0; n <= N/2; n++)
45 window[n] = 2.0f * n / (float)N;
46 for (; n <= N; n++)
47 window[n] = 2.0f - 2.0f * n / (float)N;
48 }
49 else {
50 for (n = 0; n <= L/2-1; n++)
51 window[n] = 2.0f * n / (float)N;
52 for (; n <= N; n++)
53 window[n] = 2.0f - 2.0f * n / (float)N;
54 }
55 }
56
FLAC__window_bartlett_hann(FLAC__real * window,const FLAC__int32 L)57 void FLAC__window_bartlett_hann(FLAC__real *window, const FLAC__int32 L)
58 {
59 const FLAC__int32 N = L - 1;
60 FLAC__int32 n;
61
62 for (n = 0; n < L; n++)
63 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)));
64 }
65
FLAC__window_blackman(FLAC__real * window,const FLAC__int32 L)66 void FLAC__window_blackman(FLAC__real *window, const FLAC__int32 L)
67 {
68 const FLAC__int32 N = L - 1;
69 FLAC__int32 n;
70
71 for (n = 0; n < L; n++)
72 window[n] = (FLAC__real)(0.42f - 0.5f * cos(2.0f * M_PI * n / N) + 0.08f * cos(4.0f * M_PI * n / N));
73 }
74
75 /* 4-term -92dB side-lobe */
FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real * window,const FLAC__int32 L)76 void FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real *window, const FLAC__int32 L)
77 {
78 const FLAC__int32 N = L - 1;
79 FLAC__int32 n;
80
81 for (n = 0; n <= N; n++)
82 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));
83 }
84
FLAC__window_connes(FLAC__real * window,const FLAC__int32 L)85 void FLAC__window_connes(FLAC__real *window, const FLAC__int32 L)
86 {
87 const FLAC__int32 N = L - 1;
88 const double N2 = (double)N / 2.;
89 FLAC__int32 n;
90
91 for (n = 0; n <= N; n++) {
92 double k = ((double)n - N2) / N2;
93 k = 1.0f - k * k;
94 window[n] = (FLAC__real)(k * k);
95 }
96 }
97
FLAC__window_flattop(FLAC__real * window,const FLAC__int32 L)98 void FLAC__window_flattop(FLAC__real *window, const FLAC__int32 L)
99 {
100 const FLAC__int32 N = L - 1;
101 FLAC__int32 n;
102
103 for (n = 0; n < L; n++)
104 window[n] = (FLAC__real)(0.21557895f - 0.41663158f * cos(2.0f * M_PI * n / N) + 0.277263158f * cos(4.0f * M_PI * n / N) - 0.083578947f * cos(6.0f * M_PI * n / N) + 0.006947368f * cos(8.0f * M_PI * n / N));
105 }
106
FLAC__window_gauss(FLAC__real * window,const FLAC__int32 L,const FLAC__real stddev)107 void FLAC__window_gauss(FLAC__real *window, const FLAC__int32 L, const FLAC__real stddev)
108 {
109 const FLAC__int32 N = L - 1;
110 const double N2 = (double)N / 2.;
111 FLAC__int32 n;
112
113 for (n = 0; n <= N; n++) {
114 const double k = ((double)n - N2) / (stddev * N2);
115 window[n] = (FLAC__real)exp(-0.5f * k * k);
116 }
117 }
118
FLAC__window_hamming(FLAC__real * window,const FLAC__int32 L)119 void FLAC__window_hamming(FLAC__real *window, const FLAC__int32 L)
120 {
121 const FLAC__int32 N = L - 1;
122 FLAC__int32 n;
123
124 for (n = 0; n < L; n++)
125 window[n] = (FLAC__real)(0.54f - 0.46f * cos(2.0f * M_PI * n / N));
126 }
127
FLAC__window_hann(FLAC__real * window,const FLAC__int32 L)128 void FLAC__window_hann(FLAC__real *window, const FLAC__int32 L)
129 {
130 const FLAC__int32 N = L - 1;
131 FLAC__int32 n;
132
133 for (n = 0; n < L; n++)
134 window[n] = (FLAC__real)(0.5f - 0.5f * cos(2.0f * M_PI * n / N));
135 }
136
FLAC__window_kaiser_bessel(FLAC__real * window,const FLAC__int32 L)137 void FLAC__window_kaiser_bessel(FLAC__real *window, const FLAC__int32 L)
138 {
139 const FLAC__int32 N = L - 1;
140 FLAC__int32 n;
141
142 for (n = 0; n < L; n++)
143 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));
144 }
145
FLAC__window_nuttall(FLAC__real * window,const FLAC__int32 L)146 void FLAC__window_nuttall(FLAC__real *window, const FLAC__int32 L)
147 {
148 const FLAC__int32 N = L - 1;
149 FLAC__int32 n;
150
151 for (n = 0; n < L; n++)
152 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));
153 }
154
FLAC__window_rectangle(FLAC__real * window,const FLAC__int32 L)155 void FLAC__window_rectangle(FLAC__real *window, const FLAC__int32 L)
156 {
157 FLAC__int32 n;
158
159 for (n = 0; n < L; n++)
160 window[n] = 1.0f;
161 }
162
FLAC__window_triangle(FLAC__real * window,const FLAC__int32 L)163 void FLAC__window_triangle(FLAC__real *window, const FLAC__int32 L)
164 {
165 FLAC__int32 n;
166
167 if (L & 1) {
168 for (n = 1; n <= (L+1)/2; n++)
169 window[n-1] = 2.0f * n / ((float)L + 1.0f);
170 for (; n <= L; n++)
171 window[n-1] = (float)(2 * (L - n + 1)) / ((float)L + 1.0f);
172 }
173 else {
174 for (n = 1; n <= L/2; n++)
175 window[n-1] = 2.0f * n / ((float)L + 1.0f);
176 for (; n <= L; n++)
177 window[n-1] = (float)(2 * (L - n + 1)) / ((float)L + 1.0f);
178 }
179 }
180
FLAC__window_tukey(FLAC__real * window,const FLAC__int32 L,const FLAC__real p)181 void FLAC__window_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p)
182 {
183 if (p <= 0.0)
184 FLAC__window_rectangle(window, L);
185 else if (p >= 1.0)
186 FLAC__window_hann(window, L);
187 else {
188 const FLAC__int32 Np = (FLAC__int32)(p / 2.0f * L) - 1;
189 FLAC__int32 n;
190 /* start with rectangle... */
191 FLAC__window_rectangle(window, L);
192 /* ...replace ends with hann */
193 if (Np > 0) {
194 for (n = 0; n <= Np; n++) {
195 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * n / Np));
196 window[L-Np-1+n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * (n+Np) / Np));
197 }
198 }
199 }
200 }
201
FLAC__window_partial_tukey(FLAC__real * window,const FLAC__int32 L,const FLAC__real p,const FLAC__real start,const FLAC__real end)202 void FLAC__window_partial_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p, const FLAC__real start, const FLAC__real end)
203 {
204 const FLAC__int32 start_n = (FLAC__int32)(start * L);
205 const FLAC__int32 end_n = (FLAC__int32)(end * L);
206 const FLAC__int32 N = end_n - start_n;
207 FLAC__int32 Np, n, i;
208
209 if (p <= 0.0f)
210 FLAC__window_partial_tukey(window, L, 0.05f, start, end);
211 else if (p >= 1.0f)
212 FLAC__window_partial_tukey(window, L, 0.95f, start, end);
213 else {
214
215 Np = (FLAC__int32)(p / 2.0f * N);
216
217 for (n = 0; n < start_n && n < L; n++)
218 window[n] = 0.0f;
219 for (i = 1; n < (start_n+Np) && n < L; n++, i++)
220 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Np));
221 for (; n < (end_n-Np) && n < L; n++)
222 window[n] = 1.0f;
223 for (i = Np; n < end_n && n < L; n++, i--)
224 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Np));
225 for (; n < L; n++)
226 window[n] = 0.0f;
227 }
228 }
229
FLAC__window_punchout_tukey(FLAC__real * window,const FLAC__int32 L,const FLAC__real p,const FLAC__real start,const FLAC__real end)230 void FLAC__window_punchout_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p, const FLAC__real start, const FLAC__real end)
231 {
232 const FLAC__int32 start_n = (FLAC__int32)(start * L);
233 const FLAC__int32 end_n = (FLAC__int32)(end * L);
234 FLAC__int32 Ns, Ne, n, i;
235
236 if (p <= 0.0f)
237 FLAC__window_punchout_tukey(window, L, 0.05f, start, end);
238 else if (p >= 1.0f)
239 FLAC__window_punchout_tukey(window, L, 0.95f, start, end);
240 else {
241
242 Ns = (FLAC__int32)(p / 2.0f * start_n);
243 Ne = (FLAC__int32)(p / 2.0f * (L - end_n));
244
245 for (n = 0, i = 1; n < Ns && n < L; n++, i++)
246 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ns));
247 for (; n < start_n-Ns && n < L; n++)
248 window[n] = 1.0f;
249 for (i = Ns; n < start_n && n < L; n++, i--)
250 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ns));
251 for (; n < end_n && n < L; n++)
252 window[n] = 0.0f;
253 for (i = 1; n < end_n+Ne && n < L; n++, i++)
254 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ne));
255 for (; n < L - (Ne) && n < L; n++)
256 window[n] = 1.0f;
257 for (i = Ne; n < L; n++, i--)
258 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ne));
259 }
260 }
261
FLAC__window_welch(FLAC__real * window,const FLAC__int32 L)262 void FLAC__window_welch(FLAC__real *window, const FLAC__int32 L)
263 {
264 const FLAC__int32 N = L - 1;
265 const double N2 = (double)N / 2.;
266 FLAC__int32 n;
267
268 for (n = 0; n <= N; n++) {
269 const double k = ((double)n - N2) / N2;
270 window[n] = (FLAC__real)(1.0f - k * k);
271 }
272 }
273