diff options
Diffstat (limited to 'fdk-aac/libFDK/include/fft.h')
| -rw-r--r-- | fdk-aac/libFDK/include/fft.h | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/fdk-aac/libFDK/include/fft.h b/fdk-aac/libFDK/include/fft.h new file mode 100644 index 0000000..d394046 --- /dev/null +++ b/fdk-aac/libFDK/include/fft.h @@ -0,0 +1,263 @@ +/* ----------------------------------------------------------------------------- +Software License for The Fraunhofer FDK AAC Codec Library for Android + +© Copyright 1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten +Forschung e.V. All rights reserved. + + 1. INTRODUCTION +The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software +that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding +scheme for digital audio. This FDK AAC Codec software is intended to be used on +a wide variety of Android devices. + +AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient +general perceptual audio codecs. AAC-ELD is considered the best-performing +full-bandwidth communications codec by independent studies and is widely +deployed. AAC has been standardized by ISO and IEC as part of the MPEG +specifications. + +Patent licenses for necessary patent claims for the FDK AAC Codec (including +those of Fraunhofer) may be obtained through Via Licensing +(www.vialicensing.com) or through the respective patent owners individually for +the purpose of encoding or decoding bit streams in products that are compliant +with the ISO/IEC MPEG audio standards. Please note that most manufacturers of +Android devices already license these patent claims through Via Licensing or +directly from the patent owners, and therefore FDK AAC Codec software may +already be covered under those patent licenses when it is used for those +licensed purposes only. + +Commercially-licensed AAC software libraries, including floating-point versions +with enhanced sound quality, are also available from Fraunhofer. Users are +encouraged to check the Fraunhofer website for additional applications +information and documentation. + +2. COPYRIGHT LICENSE + +Redistribution and use in source and binary forms, with or without modification, +are permitted without payment of copyright license fees provided that you +satisfy the following conditions: + +You must retain the complete text of this software license in redistributions of +the FDK AAC Codec or your modifications thereto in source code form. + +You must retain the complete text of this software license in the documentation +and/or other materials provided with redistributions of the FDK AAC Codec or +your modifications thereto in binary form. You must make available free of +charge copies of the complete source code of the FDK AAC Codec and your +modifications thereto to recipients of copies in binary form. + +The name of Fraunhofer may not be used to endorse or promote products derived +from this library without prior written permission. + +You may not charge copyright license fees for anyone to use, copy or distribute +the FDK AAC Codec software or your modifications thereto. + +Your modified versions of the FDK AAC Codec must carry prominent notices stating +that you changed the software and the date of any change. For modified versions +of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec Library for Android" +must be replaced by the term "Third-Party Modified Version of the Fraunhofer FDK +AAC Codec Library for Android." + +3. NO PATENT LICENSE + +NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without +limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE. +Fraunhofer provides no warranty of patent non-infringement with respect to this +software. + +You may use this FDK AAC Codec software or modifications thereto only for +purposes that are authorized by appropriate patent licenses. + +4. DISCLAIMER + +This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright +holders and contributors "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, +including but not limited to the implied warranties of merchantability and +fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR +CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, +or consequential damages, including but not limited to procurement of substitute +goods or services; loss of use, data, or profits, or business interruption, +however caused and on any theory of liability, whether in contract, strict +liability, or tort (including negligence), arising in any way out of the use of +this software, even if advised of the possibility of such damage. + +5. CONTACT INFORMATION + +Fraunhofer Institute for Integrated Circuits IIS +Attention: Audio and Multimedia Departments - FDK AAC LL +Am Wolfsmantel 33 +91058 Erlangen, Germany + +www.iis.fraunhofer.de/amm +amm-info@iis.fraunhofer.de +----------------------------------------------------------------------------- */ + +/******************* Library for basic calculation routines ******************** + + Author(s): Josef Hoepfl, DSP Solutions + + Description: Fix point FFT + +*******************************************************************************/ + +#ifndef FFT_H +#define FFT_H + +#include "common_fix.h" + +/** + * \brief Perform an inplace complex valued FFT of length 2^n + * + * \param length Length of the FFT to be calculated. + * \param pInput Input/Output data buffer. The input data must have at least 1 + * bit scale headroom. The values are interleaved, real/imag pairs. + * \param scalefactor Pointer to an INT, which contains the current scale of the + * input data, which is updated according to the FFT scale. + */ +void fft(int length, FIXP_DBL *pInput, INT *scalefactor); + +/** + * \brief Perform an inplace complex valued IFFT of length 2^n + * + * \param length Length of the FFT to be calculated. + * \param pInput Input/Output data buffer. The input data must have at least 1 + * bit scale headroom. The values are interleaved, real/imag pairs. + * \param scalefactor Pointer to an INT, which contains the current scale of the + * input data, which is updated according to the IFFT scale. + */ +void ifft(int length, FIXP_DBL *pInput, INT *scalefactor); + +/* + * Frequently used and fixed short length FFTs. + */ + +#ifndef FUNCTION_fft_4 +/** + * \brief Perform an inplace complex valued FFT of length 4 + * + * \param pInput Input/Output data buffer. The input data must have at least 1 + * bit scale headroom. The values are interleaved, real/imag pairs. + */ +LNK_SECTION_CODE_L1 +static FDK_FORCEINLINE void fft_4(FIXP_DBL *x) { + FIXP_DBL a00, a10, a20, a30, tmp0, tmp1; + + a00 = (x[0] + x[4]) >> 1; /* Re A + Re B */ + a10 = (x[2] + x[6]) >> 1; /* Re C + Re D */ + a20 = (x[1] + x[5]) >> 1; /* Im A + Im B */ + a30 = (x[3] + x[7]) >> 1; /* Im C + Im D */ + + x[0] = a00 + a10; /* Re A' = Re A + Re B + Re C + Re D */ + x[1] = a20 + a30; /* Im A' = Im A + Im B + Im C + Im D */ + + tmp0 = a00 - x[4]; /* Re A - Re B */ + tmp1 = a20 - x[5]; /* Im A - Im B */ + + x[4] = a00 - a10; /* Re C' = Re A + Re B - Re C - Re D */ + x[5] = a20 - a30; /* Im C' = Im A + Im B - Im C - Im D */ + + a10 = a10 - x[6]; /* Re C - Re D */ + a30 = a30 - x[7]; /* Im C - Im D */ + + x[2] = tmp0 + a30; /* Re B' = Re A - Re B + Im C - Im D */ + x[6] = tmp0 - a30; /* Re D' = Re A - Re B - Im C + Im D */ + x[3] = tmp1 - a10; /* Im B' = Im A - Im B - Re C + Re D */ + x[7] = tmp1 + a10; /* Im D' = Im A - Im B + Re C - Re D */ +} +#endif /* FUNCTION_fft_4 */ + +#ifndef FUNCTION_fft_8 +LNK_SECTION_CODE_L1 +static FDK_FORCEINLINE void fft_8(FIXP_DBL *x) { + FIXP_SPK w_PiFOURTH = {{FIXP_SGL(0x5A82), FIXP_SGL(0x5A82)}}; + + FIXP_DBL a00, a10, a20, a30; + FIXP_DBL y[16]; + + a00 = (x[0] + x[8]) >> 1; + a10 = x[4] + x[12]; + a20 = (x[1] + x[9]) >> 1; + a30 = x[5] + x[13]; + + y[0] = a00 + (a10 >> 1); + y[4] = a00 - (a10 >> 1); + y[1] = a20 + (a30 >> 1); + y[5] = a20 - (a30 >> 1); + + a00 = a00 - x[8]; + a10 = (a10 >> 1) - x[12]; + a20 = a20 - x[9]; + a30 = (a30 >> 1) - x[13]; + + y[2] = a00 + a30; + y[6] = a00 - a30; + y[3] = a20 - a10; + y[7] = a20 + a10; + + a00 = (x[2] + x[10]) >> 1; + a10 = x[6] + x[14]; + a20 = (x[3] + x[11]) >> 1; + a30 = x[7] + x[15]; + + y[8] = a00 + (a10 >> 1); + y[12] = a00 - (a10 >> 1); + y[9] = a20 + (a30 >> 1); + y[13] = a20 - (a30 >> 1); + + a00 = a00 - x[10]; + a10 = (a10 >> 1) - x[14]; + a20 = a20 - x[11]; + a30 = (a30 >> 1) - x[15]; + + y[10] = a00 + a30; + y[14] = a00 - a30; + y[11] = a20 - a10; + y[15] = a20 + a10; + + FIXP_DBL vr, vi, ur, ui; + + ur = y[0] >> 1; + ui = y[1] >> 1; + vr = y[8]; + vi = y[9]; + x[0] = ur + (vr >> 1); + x[1] = ui + (vi >> 1); + x[8] = ur - (vr >> 1); + x[9] = ui - (vi >> 1); + + ur = y[4] >> 1; + ui = y[5] >> 1; + vi = y[12]; + vr = y[13]; + x[4] = ur + (vr >> 1); + x[5] = ui - (vi >> 1); + x[12] = ur - (vr >> 1); + x[13] = ui + (vi >> 1); + + ur = y[10]; + ui = y[11]; + + cplxMultDiv2(&vi, &vr, ui, ur, w_PiFOURTH); + + ur = y[2]; + ui = y[3]; + x[2] = (ur >> 1) + vr; + x[3] = (ui >> 1) + vi; + x[10] = (ur >> 1) - vr; + x[11] = (ui >> 1) - vi; + + ur = y[14]; + ui = y[15]; + + cplxMultDiv2(&vr, &vi, ui, ur, w_PiFOURTH); + + ur = y[6]; + ui = y[7]; + x[6] = (ur >> 1) + vr; + x[7] = (ui >> 1) - vi; + x[14] = (ur >> 1) - vr; + x[15] = (ui >> 1) + vi; +} +#endif /* FUNCTION_fft_8 */ + +#endif |