1 /* libFLAC - Free Lossless Audio Codec library 2 * Copyright (C) 2006-2009 Josh Coalson 3 * Copyright (C) 2011-2014 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 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 / (float)N; 62 } 63 } 64 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))); 72 } 73 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 */ 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 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 } 105 106 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 } 114 115 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 } 126 127 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 } 135 136 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 } 144 145 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 } 153 154 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 } 162 163 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 } 170 171 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 + 1.0f); 184 for (; n <= L; n++) 185 window[n-1] = (float)(2 * (L - n + 1)) / ((float)L + 1.0f); 186 } 187 } 188 189 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 } 209 210 void FLAC__window_partial_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p, const FLAC__real start, const FLAC__real end) 211 { 212 const FLAC__int32 start_n = (FLAC__int32)(start * L); 213 const FLAC__int32 end_n = (FLAC__int32)(end * L); 214 const FLAC__int32 N = end_n - start_n; 215 FLAC__int32 Np, n, i; 216 217 if (p <= 0.0f) 218 FLAC__window_partial_tukey(window, L, 0.05f, start, end); 219 else if (p >= 1.0f) 220 FLAC__window_partial_tukey(window, L, 0.95f, start, end); 221 else { 222 223 Np = (FLAC__int32)(p / 2.0f * N); 224 225 for (n = 0; n < start_n && n < L; n++) 226 window[n] = 0.0f; 227 for (i = 1; n < (start_n+Np) && n < L; n++, i++) 228 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Np)); 229 for (; n < (end_n-Np) && n < L; n++) 230 window[n] = 1.0f; 231 for (i = Np; n < end_n && n < L; n++, i--) 232 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Np)); 233 for (; n < L; n++) 234 window[n] = 0.0f; 235 } 236 } 237 238 void FLAC__window_punchout_tukey(FLAC__real *window, const FLAC__int32 L, const FLAC__real p, const FLAC__real start, const FLAC__real end) 239 { 240 const FLAC__int32 start_n = (FLAC__int32)(start * L); 241 const FLAC__int32 end_n = (FLAC__int32)(end * L); 242 FLAC__int32 Ns, Ne, n, i; 243 244 if (p <= 0.0f) 245 FLAC__window_punchout_tukey(window, L, 0.05f, start, end); 246 else if (p >= 1.0f) 247 FLAC__window_punchout_tukey(window, L, 0.95f, start, end); 248 else { 249 250 Ns = (FLAC__int32)(p / 2.0f * start_n); 251 Ne = (FLAC__int32)(p / 2.0f * (L - end_n)); 252 253 for (n = 0, i = 1; n < Ns && n < L; n++, i++) 254 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ns)); 255 for (; n < start_n-Ns && n < L; n++) 256 window[n] = 1.0f; 257 for (i = Ns; n < start_n && n < L; n++, i--) 258 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ns)); 259 for (; n < end_n && n < L; n++) 260 window[n] = 0.0f; 261 for (i = 1; n < end_n+Ne && n < L; n++, i++) 262 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ne)); 263 for (; n < L - (Ne) && n < L; n++) 264 window[n] = 1.0f; 265 for (i = Ne; n < L; n++, i--) 266 window[n] = (FLAC__real)(0.5f - 0.5f * cos(M_PI * i / Ne)); 267 } 268 } 269 270 void FLAC__window_welch(FLAC__real *window, const FLAC__int32 L) 271 { 272 const FLAC__int32 N = L - 1; 273 const double N2 = (double)N / 2.; 274 FLAC__int32 n; 275 276 for (n = 0; n <= N; n++) { 277 const double k = ((double)n - N2) / N2; 278 window[n] = (FLAC__real)(1.0f - k * k); 279 } 280 } 281 282 #endif /* !defined FLAC__INTEGER_ONLY_LIBRARY */ 283
