1 /* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2006-2009 Josh Coalson
3 * Copyright (C) 2011-2013 Xiph.Org Foundation
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
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.
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.
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.
38 #include "FLAC/assert.h"
39 #include "FLAC/format.h"
40 #include "private/window.h"
42 #ifndef FLAC__INTEGER_ONLY_LIBRARY
45 /* math.h in VC++ doesn't seem to have this (how Microsoft is that?) */
46 #define M_PI 3.14159265358979323846
50 void FLAC__window_bartlett(FLAC__real *window, const FLAC__int32 L)
52 const FLAC__int32 N = L - 1;
56 for (n = 0; n <= N/2; n++)
57 window[n] = 2.0f * n / (float)N;
59 window[n] = 2.0f - 2.0f * n / (float)N;
62 for (n = 0; n <= L/2-1; n++)
63 window[n] = 2.0f * n / (float)N;
65 window[n] = 2.0f - 2.0f * (N-n) / (float)N;
69 void FLAC__window_bartlett_hann(FLAC__real *window, const FLAC__int32 L)
71 const FLAC__int32 N = L - 1;
74 for (n = 0; n < L; n++)
75 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)));
78 void FLAC__window_blackman(FLAC__real *window, const FLAC__int32 L)
80 const FLAC__int32 N = L - 1;
83 for (n = 0; n < L; n++)
84 window[n] = (FLAC__real)(0.42f - 0.5f * cos(2.0f * M_PI * n / N) + 0.08f * cos(4.0f * M_PI * n / N));
87 /* 4-term -92dB side-lobe */
88 void FLAC__window_blackman_harris_4term_92db_sidelobe(FLAC__real *window, const FLAC__int32 L)
90 const FLAC__int32 N = L - 1;
93 for (n = 0; n <= N; n++)
94 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));
97 void FLAC__window_connes(FLAC__real *window, const FLAC__int32 L)
99 const FLAC__int32 N = L - 1;
100 const double N2 = (double)N / 2.;
103 for (n = 0; n <= N; n++) {
104 double k = ((double)n - N2) / N2;
106 window[n] = (FLAC__real)(k * k);
110 void FLAC__window_flattop(FLAC__real *window, const FLAC__int32 L)
112 const FLAC__int32 N = L - 1;
115 for (n = 0; n < L; n++)
116 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));
119 void FLAC__window_gauss(FLAC__real *window, const FLAC__int32 L, const FLAC__real stddev)
121 const FLAC__int32 N = L - 1;
122 const double N2 = (double)N / 2.;
125 for (n = 0; n <= N; n++) {
126 const double k = ((double)n - N2) / (stddev * N2);
127 window[n] = (FLAC__real)exp(-0.5f * k * k);
131 void FLAC__window_hamming(FLAC__real *window, const FLAC__int32 L)
133 const FLAC__int32 N = L - 1;
136 for (n = 0; n < L; n++)
137 window[n] = (FLAC__real)(0.54f - 0.46f * cos(2.0f * M_PI * n / N));
140 void FLAC__window_hann(FLAC__real *window, const FLAC__int32 L)
142 const FLAC__int32 N = L - 1;
145 for (n = 0; n < L; n++)
146 window[n] = (FLAC__real)(0.5f - 0.5f * cos(2.0f * M_PI * n / N));
149 void FLAC__window_kaiser_bessel(FLAC__real *window, const FLAC__int32 L)
151 const FLAC__int32 N = L - 1;
154 for (n = 0; n < L; n++)
155 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));
158 void FLAC__window_nuttall(FLAC__real *window, const FLAC__int32 L)
160 const FLAC__int32 N = L - 1;
163 for (n = 0; n < L; n++)
164 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));
167 void FLAC__window_rectangle(FLAC__real *window, const FLAC__int32 L)
171 for (n = 0; n < L; n++)
175 void FLAC__window_triangle(FLAC__real *window, const FLAC__int32 L)
180 for (n = 1; n <= L+1/2; n++)
181 window[n-1] = 2.0f * n / ((float)L + 1.0f);
183 window[n-1] = - (float)(2 * (L - n + 1)) / ((float)L + 1.0f);
186 for (n = 1; n <= L/2; n++)
187 window[n-1] = 2.0f * n / (float)L;
189 window[n-1] = ((float)(2 * (L - n)) + 1.0f) / (float)L;
193 void FLAC__window_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p)
196 FLAC__window_rectangle(window, L);
198 FLAC__window_hann(window, L);
200 const FLAC__int32 Np = (FLAC__int32)(p / 2.0f * L) - 1;
202 /* start with rectangle... */
203 FLAC__window_rectangle(window, L);
204 /* ...replace ends with hann */
206 for (n = 0; n <= Np; n++) {
207 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * n / Np));
208 window[L-Np-1+n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * (n+Np) / Np));
214 void FLAC__window_welch(FLAC__real *window, const FLAC__int32 L)
216 const FLAC__int32 N = L - 1;
217 const double N2 = (double)N / 2.;
220 for (n = 0; n <= N; n++) {
221 const double k = ((double)n - N2) / N2;
222 window[n] = (FLAC__real)(1.0f - k * k);
226 #endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */