1
2 /* -----------------------------------------------------------------------------------------------------------
3 Software License for The Fraunhofer FDK AAC Codec Library for Android
4
5 � Copyright 1995 - 2013 Fraunhofer-Gesellschaft zur F�rderung 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@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
fft_4(FIXP_DBL * x)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
fft_8(FIXP_DBL * x)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