android / platform / external / aac / ce97e7d55e1f69683b5bc8f19cc8da8c85bc2cd4 / . / libFDK / include / fft.h

/* ----------------------------------------------------------------------------- | |

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 void FDK_FORCEINLINE 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 void FDK_FORCEINLINE 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 |