1 2 /* ----------------------------------------------------------------------------------------------------------- 3 Software License for The Fraunhofer FDK AAC Codec Library for Android 4 5 Copyright 1995 - 2013 Fraunhofer-Gesellschaft zur Frderung der angewandten Forschung e.V. 6 All rights reserved. 7 8 1. INTRODUCTION 9 The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements 10 the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio. 11 This FDK AAC Codec software is intended to be used on a wide variety of Android devices. 12 13 AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual 14 audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by 15 independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part 16 of the MPEG specifications. 17 18 Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer) 19 may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners 20 individually for the purpose of encoding or decoding bit streams in products that are compliant with 21 the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license 22 these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec 23 software may already be covered under those patent licenses when it is used for those licensed purposes only. 24 25 Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality, 26 are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional 27 applications information and documentation. 28 29 2. COPYRIGHT LICENSE 30 31 Redistribution and use in source and binary forms, with or without modification, are permitted without 32 payment of copyright license fees provided that you satisfy the following conditions: 33 34 You must retain the complete text of this software license in redistributions of the FDK AAC Codec or 35 your modifications thereto in source code form. 36 37 You must retain the complete text of this software license in the documentation and/or other materials 38 provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form. 39 You must make available free of charge copies of the complete source code of the FDK AAC Codec and your 40 modifications thereto to recipients of copies in binary form. 41 42 The name of Fraunhofer may not be used to endorse or promote products derived from this library without 43 prior written permission. 44 45 You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec 46 software or your modifications thereto. 47 48 Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software 49 and the date of any change. For modified versions of the FDK AAC Codec, the term 50 "Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term 51 "Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android." 52 53 3. NO PATENT LICENSE 54 55 NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer, 56 ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with 57 respect to this software. 58 59 You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized 60 by appropriate patent licenses. 61 62 4. DISCLAIMER 63 64 This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors 65 "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties 66 of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 67 CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages, 68 including but not limited to procurement of substitute goods or services; loss of use, data, or profits, 69 or business interruption, however caused and on any theory of liability, whether in contract, strict 70 liability, or tort (including negligence), arising in any way out of the use of this software, even if 71 advised of the possibility of such damage. 72 73 5. CONTACT INFORMATION 74 75 Fraunhofer Institute for Integrated Circuits IIS 76 Attention: Audio and Multimedia Departments - FDK AAC LL 77 Am Wolfsmantel 33 78 91058 Erlangen, Germany 79 80 www.iis.fraunhofer.de/amm 81 amm-info (at) iis.fraunhofer.de 82 ----------------------------------------------------------------------------------------------------------- */ 83 84 /*************************** Fraunhofer IIS FDK Tools ********************** 85 86 Author(s): Josef Hoepfl, DSP Solutions 87 Description: Fix point FFT 88 89 ******************************************************************************/ 90 91 #ifndef __FFT_H__ 92 #define __FFT_H__ 93 94 #include "common_fix.h" 95 96 /** 97 * \brief Perform an inplace complex valued FFT of length 2^n 98 * 99 * \param length Length of the FFT to be calculated. 100 * \param pInput Input/Output data buffer. The input data must have at least 1 bit scale headroom. 101 * The values are interleaved, real/imag pairs. 102 * \param scalefactor Pointer to an INT, which contains the current scale of the input data, 103 * which is updated according to the FFT scale. 104 */ 105 void fft(int length, FIXP_DBL *pInput, INT *scalefactor); 106 107 /** 108 * \brief Perform an inplace complex valued IFFT of length 2^n 109 * 110 * \param length Length of the FFT to be calculated. 111 * \param pInput Input/Output data buffer. The input data must have at least 1 bit scale headroom. 112 * The values are interleaved, real/imag pairs. 113 * \param scalefactor Pointer to an INT, which contains the current scale of the input data, 114 * which is updated according to the IFFT scale. 115 */ 116 void ifft(int length, FIXP_DBL *pInput, INT *scalefactor); 117 118 119 /* 120 * Frequently used and fixed short length FFTs. 121 */ 122 123 LNK_SECTION_CODE_L1 124 static void FORCEINLINE fft_4(FIXP_DBL *x) 125 { 126 FIXP_DBL a00, a10, a20, a30, tmp0, tmp1; 127 128 a00 = (x[0] + x[4])>>1; /* Re A + Re B */ 129 a10 = (x[2] + x[6])>>1; /* Re C + Re D */ 130 a20 = (x[1] + x[5])>>1; /* Im A + Im B */ 131 a30 = (x[3] + x[7])>>1; /* Im C + Im D */ 132 133 x[0] = a00 + a10; /* Re A' = Re A + Re B + Re C + Re D */ 134 x[1] = a20 + a30; /* Im A' = Im A + Im B + Im C + Im D */ 135 136 tmp0 = a00 - x[4]; /* Re A - Re B */ 137 tmp1 = a20 - x[5]; /* Im A - Im B */ 138 139 x[4] = a00 - a10; /* Re C' = Re A + Re B - Re C - Re D */ 140 x[5] = a20 - a30; /* Im C' = Im A + Im B - Im C - Im D */ 141 142 a10 = a10 - x[6]; /* Re C - Re D */ 143 a30 = a30 - x[7]; /* Im C - Im D */ 144 145 x[2] = tmp0 + a30; /* Re B' = Re A - Re B + Im C - Im D */ 146 x[6] = tmp0 - a30; /* Re D' = Re A - Re B - Im C + Im D */ 147 x[3] = tmp1 - a10; /* Im B' = Im A - Im B - Re C + Re D */ 148 x[7] = tmp1 + a10; /* Im D' = Im A - Im B + Re C - Re D */ 149 } 150 151 LNK_SECTION_CODE_L1 152 static void FORCEINLINE fft_8(FIXP_DBL *x) 153 { 154 #define W_PiFOURTH STC(0x5a82799a) 155 156 FIXP_DBL a00, a10, a20, a30; 157 FIXP_DBL y[16]; 158 159 a00 = (x[0] + x[8])>>1; 160 a10 = x[4] + x[12]; 161 a20 = (x[1] + x[9])>>1; 162 a30 = x[5] + x[13]; 163 164 y[0] = a00 + (a10>>1); 165 y[4] = a00 - (a10>>1); 166 y[1] = a20 + (a30>>1); 167 y[5] = a20 - (a30>>1); 168 169 a00 = a00 - x[8]; 170 a10 = (a10>>1) - x[12]; 171 a20 = a20 - x[9]; 172 a30 = (a30>>1) - x[13]; 173 174 y[2] = a00 + a30; 175 y[6] = a00 - a30; 176 y[3] = a20 - a10; 177 y[7] = a20 + a10; 178 179 a00 = (x[2] + x[10])>>1; 180 a10 = x[6] + x[14]; 181 a20 = (x[3] + x[11])>>1; 182 a30 = x[7] + x[15]; 183 184 y[8] = a00 + (a10>>1); 185 y[12] = a00 - (a10>>1); 186 y[9] = a20 + (a30>>1); 187 y[13] = a20 - (a30>>1); 188 189 a00 = a00 - x[10]; 190 a10 = (a10>>1) - x[14]; 191 a20 = a20 - x[11]; 192 a30 = (a30>>1) - x[15]; 193 194 y[10] = a00 + a30; 195 y[14] = a00 - a30; 196 y[11] = a20 - a10; 197 y[15] = a20 + a10; 198 199 FIXP_DBL vr, vi, ur, ui; 200 201 ur = y[0]>>1; 202 ui = y[1]>>1; 203 vr = y[8]; 204 vi = y[9]; 205 x[0] = ur + (vr>>1); 206 x[1] = ui + (vi>>1); 207 x[8] = ur - (vr>>1); 208 x[9] = ui - (vi>>1); 209 210 ur = y[4]>>1; 211 ui = y[5]>>1; 212 vi = y[12]; 213 vr = y[13]; 214 x[4] = ur + (vr>>1); 215 x[5] = ui - (vi>>1); 216 x[12] = ur - (vr>>1); 217 x[13] = ui + (vi>>1); 218 219 ur = y[10]; 220 ui = y[11]; 221 vr = fMultDiv2(ui+ur,W_PiFOURTH); 222 vi = fMultDiv2(ui-ur,W_PiFOURTH); 223 ur = y[2]; 224 ui = y[3]; 225 x[2] = (ur>>1) + vr; 226 x[3] = (ui>>1) + vi; 227 x[10] = (ur>>1) - vr; 228 x[11] = (ui>>1) - vi; 229 230 ur = y[14]; 231 ui = y[15]; 232 vr = fMultDiv2(ui-ur,W_PiFOURTH); 233 vi = fMultDiv2(ui+ur,W_PiFOURTH); 234 ur = y[6]; 235 ui = y[7]; 236 x[6] = (ur>>1) + vr; 237 x[7] = (ui>>1) - vi; 238 x[14] = (ur>>1) - vr; 239 x[15] = (ui>>1) + vi; 240 } 241 242 /** 243 * \brief FFT of fixed length 16 244 */ 245 inline void fft_16(FIXP_DBL *x); 246 247 /** 248 * \brief FFT of fixed length 32 249 */ 250 inline void fft_32(FIXP_DBL *x); 251 252 253 #endif 254
