1 /* -----------------------------------------------------------------------------
2 Software License for The Fraunhofer FDK AAC Codec Library for Android
3
4 © Copyright 1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
5 Forschung e.V. All rights reserved.
6
7 1. INTRODUCTION
8 The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software
9 that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding
10 scheme for digital audio. This FDK AAC Codec software is intended to be used on
11 a wide variety of Android devices.
12
13 AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient
14 general perceptual audio codecs. AAC-ELD is considered the best-performing
15 full-bandwidth communications codec by independent studies and is widely
16 deployed. AAC has been standardized by ISO and IEC as part of the MPEG
17 specifications.
18
19 Patent licenses for necessary patent claims for the FDK AAC Codec (including
20 those of Fraunhofer) may be obtained through Via Licensing
21 (www.vialicensing.com) or through the respective patent owners individually for
22 the purpose of encoding or decoding bit streams in products that are compliant
23 with the ISO/IEC MPEG audio standards. Please note that most manufacturers of
24 Android devices already license these patent claims through Via Licensing or
25 directly from the patent owners, and therefore FDK AAC Codec software may
26 already be covered under those patent licenses when it is used for those
27 licensed purposes only.
28
29 Commercially-licensed AAC software libraries, including floating-point versions
30 with enhanced sound quality, are also available from Fraunhofer. Users are
31 encouraged to check the Fraunhofer website for additional applications
32 information and documentation.
33
34 2. COPYRIGHT LICENSE
35
36 Redistribution and use in source and binary forms, with or without modification,
37 are permitted without payment of copyright license fees provided that you
38 satisfy the following conditions:
39
40 You must retain the complete text of this software license in redistributions of
41 the FDK AAC Codec or your modifications thereto in source code form.
42
43 You must retain the complete text of this software license in the documentation
44 and/or other materials provided with redistributions of the FDK AAC Codec or
45 your modifications thereto in binary form. You must make available free of
46 charge copies of the complete source code of the FDK AAC Codec and your
47 modifications thereto to recipients of copies in binary form.
48
49 The name of Fraunhofer may not be used to endorse or promote products derived
50 from this library without prior written permission.
51
52 You may not charge copyright license fees for anyone to use, copy or distribute
53 the FDK AAC Codec software or your modifications thereto.
54
55 Your modified versions of the FDK AAC Codec must carry prominent notices stating
56 that you changed the software and the date of any change. For modified versions
57 of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec Library for Android"
58 must be replaced by the term "Third-Party Modified Version of the Fraunhofer FDK
59 AAC Codec Library for Android."
60
61 3. NO PATENT LICENSE
62
63 NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without
64 limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE.
65 Fraunhofer provides no warranty of patent non-infringement with respect to this
66 software.
67
68 You may use this FDK AAC Codec software or modifications thereto only for
69 purposes that are authorized by appropriate patent licenses.
70
71 4. DISCLAIMER
72
73 This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright
74 holders and contributors "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES,
75 including but not limited to the implied warranties of merchantability and
76 fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
77 CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary,
78 or consequential damages, including but not limited to procurement of substitute
79 goods or services; loss of use, data, or profits, or business interruption,
80 however caused and on any theory of liability, whether in contract, strict
81 liability, or tort (including negligence), arising in any way out of the use of
82 this software, even if advised of the possibility of such damage.
83
84 5. CONTACT INFORMATION
85
86 Fraunhofer Institute for Integrated Circuits IIS
87 Attention: Audio and Multimedia Departments - FDK AAC LL
88 Am Wolfsmantel 33
89 91058 Erlangen, Germany
90
91 www.iis.fraunhofer.de/amm
92 amm-info@iis.fraunhofer.de
93 ----------------------------------------------------------------------------- */
94
95 /******************* Library for basic calculation routines ********************
96
97 Author(s): Josef Hoepfl, DSP Solutions
98
99 Description: Fix point FFT
100
101 *******************************************************************************/
102
103 #ifndef FFT_H
104 #define FFT_H
105
106 #include "common_fix.h"
107
108 /**
109 * \brief Perform an inplace complex valued FFT of length 2^n
110 *
111 * \param length Length of the FFT to be calculated.
112 * \param pInput Input/Output data buffer. The input data must have at least 1
113 * bit scale headroom. The values are interleaved, real/imag pairs.
114 * \param scalefactor Pointer to an INT, which contains the current scale of the
115 * input data, which is updated according to the FFT scale.
116 */
117 void fft(int length, FIXP_DBL *pInput, INT *scalefactor);
118
119 /**
120 * \brief Perform an inplace complex valued IFFT of length 2^n
121 *
122 * \param length Length of the FFT to be calculated.
123 * \param pInput Input/Output data buffer. The input data must have at least 1
124 * bit scale headroom. The values are interleaved, real/imag pairs.
125 * \param scalefactor Pointer to an INT, which contains the current scale of the
126 * input data, which is updated according to the IFFT scale.
127 */
128 void ifft(int length, FIXP_DBL *pInput, INT *scalefactor);
129
130 /*
131 * Frequently used and fixed short length FFTs.
132 */
133
134 #ifndef FUNCTION_fft_4
135 /**
136 * \brief Perform an inplace complex valued FFT of length 4
137 *
138 * \param pInput Input/Output data buffer. The input data must have at least 1
139 * bit scale headroom. The values are interleaved, real/imag pairs.
140 */
141 LNK_SECTION_CODE_L1
fft_4(FIXP_DBL * x)142 static void FDK_FORCEINLINE fft_4(FIXP_DBL *x) {
143 FIXP_DBL a00, a10, a20, a30, tmp0, tmp1;
144
145 a00 = (x[0] + x[4]) >> 1; /* Re A + Re B */
146 a10 = (x[2] + x[6]) >> 1; /* Re C + Re D */
147 a20 = (x[1] + x[5]) >> 1; /* Im A + Im B */
148 a30 = (x[3] + x[7]) >> 1; /* Im C + Im D */
149
150 x[0] = a00 + a10; /* Re A' = Re A + Re B + Re C + Re D */
151 x[1] = a20 + a30; /* Im A' = Im A + Im B + Im C + Im D */
152
153 tmp0 = a00 - x[4]; /* Re A - Re B */
154 tmp1 = a20 - x[5]; /* Im A - Im B */
155
156 x[4] = a00 - a10; /* Re C' = Re A + Re B - Re C - Re D */
157 x[5] = a20 - a30; /* Im C' = Im A + Im B - Im C - Im D */
158
159 a10 = a10 - x[6]; /* Re C - Re D */
160 a30 = a30 - x[7]; /* Im C - Im D */
161
162 x[2] = tmp0 + a30; /* Re B' = Re A - Re B + Im C - Im D */
163 x[6] = tmp0 - a30; /* Re D' = Re A - Re B - Im C + Im D */
164 x[3] = tmp1 - a10; /* Im B' = Im A - Im B - Re C + Re D */
165 x[7] = tmp1 + a10; /* Im D' = Im A - Im B + Re C - Re D */
166 }
167 #endif /* FUNCTION_fft_4 */
168
169 #ifndef FUNCTION_fft_8
170 LNK_SECTION_CODE_L1
fft_8(FIXP_DBL * x)171 static void FDK_FORCEINLINE fft_8(FIXP_DBL *x) {
172 FIXP_SPK w_PiFOURTH = {{FIXP_SGL(0x5A82), FIXP_SGL(0x5A82)}};
173
174 FIXP_DBL a00, a10, a20, a30;
175 FIXP_DBL y[16];
176
177 a00 = (x[0] + x[8]) >> 1;
178 a10 = x[4] + x[12];
179 a20 = (x[1] + x[9]) >> 1;
180 a30 = x[5] + x[13];
181
182 y[0] = a00 + (a10 >> 1);
183 y[4] = a00 - (a10 >> 1);
184 y[1] = a20 + (a30 >> 1);
185 y[5] = a20 - (a30 >> 1);
186
187 a00 = a00 - x[8];
188 a10 = (a10 >> 1) - x[12];
189 a20 = a20 - x[9];
190 a30 = (a30 >> 1) - x[13];
191
192 y[2] = a00 + a30;
193 y[6] = a00 - a30;
194 y[3] = a20 - a10;
195 y[7] = a20 + a10;
196
197 a00 = (x[2] + x[10]) >> 1;
198 a10 = x[6] + x[14];
199 a20 = (x[3] + x[11]) >> 1;
200 a30 = x[7] + x[15];
201
202 y[8] = a00 + (a10 >> 1);
203 y[12] = a00 - (a10 >> 1);
204 y[9] = a20 + (a30 >> 1);
205 y[13] = a20 - (a30 >> 1);
206
207 a00 = a00 - x[10];
208 a10 = (a10 >> 1) - x[14];
209 a20 = a20 - x[11];
210 a30 = (a30 >> 1) - x[15];
211
212 y[10] = a00 + a30;
213 y[14] = a00 - a30;
214 y[11] = a20 - a10;
215 y[15] = a20 + a10;
216
217 FIXP_DBL vr, vi, ur, ui;
218
219 ur = y[0] >> 1;
220 ui = y[1] >> 1;
221 vr = y[8];
222 vi = y[9];
223 x[0] = ur + (vr >> 1);
224 x[1] = ui + (vi >> 1);
225 x[8] = ur - (vr >> 1);
226 x[9] = ui - (vi >> 1);
227
228 ur = y[4] >> 1;
229 ui = y[5] >> 1;
230 vi = y[12];
231 vr = y[13];
232 x[4] = ur + (vr >> 1);
233 x[5] = ui - (vi >> 1);
234 x[12] = ur - (vr >> 1);
235 x[13] = ui + (vi >> 1);
236
237 ur = y[10];
238 ui = y[11];
239
240 cplxMultDiv2(&vi, &vr, ui, ur, w_PiFOURTH);
241
242 ur = y[2];
243 ui = y[3];
244 x[2] = (ur >> 1) + vr;
245 x[3] = (ui >> 1) + vi;
246 x[10] = (ur >> 1) - vr;
247 x[11] = (ui >> 1) - vi;
248
249 ur = y[14];
250 ui = y[15];
251
252 cplxMultDiv2(&vr, &vi, ui, ur, w_PiFOURTH);
253
254 ur = y[6];
255 ui = y[7];
256 x[6] = (ur >> 1) + vr;
257 x[7] = (ui >> 1) - vi;
258 x[14] = (ur >> 1) - vr;
259 x[15] = (ui >> 1) + vi;
260 }
261 #endif /* FUNCTION_fft_8 */
262
263 #endif
264