2 /* -----------------------------------------------------------------------------------------------------------
3 Software License for The Fraunhofer FDK AAC Codec Library for Android
5 © Copyright 1995 - 2013 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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.
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.
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.
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.
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:
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.
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.
42 The name of Fraunhofer may not be used to endorse or promote products derived from this library without
43 prior written permission.
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.
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."
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.
59 You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized
60 by appropriate patent licenses.
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.
73 5. CONTACT INFORMATION
75 Fraunhofer Institute for Integrated Circuits IIS
76 Attention: Audio and Multimedia Departments - FDK AAC LL
78 91058 Erlangen, Germany
80 www.iis.fraunhofer.de/amm
81 amm-info@iis.fraunhofer.de
82 ----------------------------------------------------------------------------------------------------------- */
84 /*************************** Fraunhofer IIS FDK Tools **********************
86 Author(s): Josef Hoepfl, DSP Solutions
87 Description: Fix point FFT
89 ******************************************************************************/
94 #include "common_fix.h"
97 * \brief Perform an inplace complex valued FFT of length 2^n
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.
105 void fft(int length
, FIXP_DBL
*pInput
, INT
*scalefactor
);
108 * \brief Perform an inplace complex valued IFFT of length 2^n
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.
116 void ifft(int length
, FIXP_DBL
*pInput
, INT
*scalefactor
);
120 * Frequently used and fixed short length FFTs.
124 static void FORCEINLINE
fft_4(FIXP_DBL
*x
)
126 FIXP_DBL a00
, a10
, a20
, a30
, tmp0
, tmp1
;
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 */
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 */
136 tmp0
= a00
- x
[4]; /* Re A - Re B */
137 tmp1
= a20
- x
[5]; /* Im A - Im B */
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 */
142 a10
= a10
- x
[6]; /* Re C - Re D */
143 a30
= a30
- x
[7]; /* Im C - Im D */
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 */
152 static void FORCEINLINE
fft_8(FIXP_DBL
*x
)
154 #define W_PiFOURTH STC(0x5a82799a)
156 FIXP_DBL a00
, a10
, a20
, a30
;
159 a00
= (x
[0] + x
[8])>>1;
161 a20
= (x
[1] + x
[9])>>1;
164 y
[0] = a00
+ (a10
>>1);
165 y
[4] = a00
- (a10
>>1);
166 y
[1] = a20
+ (a30
>>1);
167 y
[5] = a20
- (a30
>>1);
170 a10
= (a10
>>1) - x
[12];
172 a30
= (a30
>>1) - x
[13];
179 a00
= (x
[2] + x
[10])>>1;
181 a20
= (x
[3] + x
[11])>>1;
184 y
[8] = a00
+ (a10
>>1);
185 y
[12] = a00
- (a10
>>1);
186 y
[9] = a20
+ (a30
>>1);
187 y
[13] = a20
- (a30
>>1);
190 a10
= (a10
>>1) - x
[14];
192 a30
= (a30
>>1) - x
[15];
199 FIXP_DBL vr
, vi
, ur
, ui
;
216 x
[12] = ur
- (vr
>>1);
217 x
[13] = ui
+ (vi
>>1);
221 vr
= fMultDiv2(ui
+ur
,W_PiFOURTH
);
222 vi
= fMultDiv2(ui
-ur
,W_PiFOURTH
);
227 x
[10] = (ur
>>1) - vr
;
228 x
[11] = (ui
>>1) - vi
;
232 vr
= fMultDiv2(ui
-ur
,W_PiFOURTH
);
233 vi
= fMultDiv2(ui
+ur
,W_PiFOURTH
);
238 x
[14] = (ur
>>1) - vr
;
239 x
[15] = (ui
>>1) + vi
;
243 * \brief FFT of fixed length 16
245 inline void fft_16(FIXP_DBL
*x
);
248 * \brief FFT of fixed length 32
250 inline void fft_32(FIXP_DBL
*x
);