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 FDK_FORCEINLINE void 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 FDK_FORCEINLINE void 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