fdk-aac/libFDK/include/dct.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
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limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE.
Fraunhofer provides no warranty of patent non-infringement with respect to this
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You may use this FDK AAC Codec software or modifications thereto only for
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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,
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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):

   Description: Library functions to calculate standard DCTs. This will most
                likely be replaced by hand-optimized functions for the specific
                target processor.

*******************************************************************************/

#ifndef DCT_H
#define DCT_H

#include "common_fix.h"

void dct_getTables(const FIXP_WTP **ptwiddle, const FIXP_STP **sin_twiddle,
                   int *sin_step, int length);

/**
 * \brief Calculate DCT type II of given length. The DCT IV is
 *        calculated by a complex FFT, with some pre and post twiddeling.
 *        A factor of sqrt(2/(N-1)) is NOT applied.
 * \param pDat pointer to input/output data (in place processing).
 * \param size size of pDat.
 * \param pDat_e pointer to an integer containing the exponent of the data
 *               referenced by pDat. The exponent is updated accordingly.
 */
void dct_II(FIXP_DBL *pDat, FIXP_DBL *tmp, int size, int *pDat_e);

/**
 * \brief Calculate DCT type III of given length. The DCT IV is
 *        calculated by a complex FFT, with some pre and post twiddeling.
 *        Note that the factor 0.5 for the sum term x[0] is 1.0 instead of 0.5.
 *        A factor of sqrt(2/N) is NOT applied.
 * \param pDat pointer to input/output data (in place processing).
 * \param size size of pDat.
 * \param pDat_e pointer to an integer containing the exponent of the data
 *               referenced by pDat. The exponent is updated accordingly.
 */
void dct_III(FIXP_DBL *pDat, FIXP_DBL *tmp, int size, int *pDat_e);

/**
 * \brief Calculate DST type III of given length. The DST III is
 *        calculated by a DCT III of mirrored input and sign-flipping of odd
 *        output coefficients.
 *        Note that the factor 0.5 for the sum term x[N-1] is 1.0 instead of
 * 0.5. A factor of sqrt(2/N) is NOT applied.
 * \param pDat pointer to input/output data (in place processing).
 * \param size size of pDat.
 * \param pDat_e pointer to an integer containing the exponent of the data
 *               referenced by pDat. The exponent is updated accordingly.
 */
void dst_III(FIXP_DBL *pDat, FIXP_DBL *tmp, int size, int *pDat_e);

/**
 * \brief Calculate DCT type IV of given length. The DCT IV is
 *        calculated by a complex FFT, with some pre and post twiddeling.
 *        A factor of sqrt(2/N) is NOT applied.
 * \param pDat pointer to input/output data (in place processing).
 * \param size size of pDat.
 * \param pDat_e pointer to an integer containing the exponent of the data
 *               referenced by pDat. The exponent is updated accordingly.
 */
void dct_IV(FIXP_DBL *pDat, int size, int *pDat_e);

/**
 * \brief Calculate DST type IV of given length. The DST IV is
 *        calculated by a complex FFT, with some pre and post twiddeling.
 *        A factor of sqrt(2/N) is NOT applied.
 * \param pDat pointer to input/output data (in place processing).
 * \param size size of pDat.
 * \param pDat_e pointer to an integer containing the exponent of the data
 *               referenced by pDat. The exponent is updated accordingly.
 */
void dst_IV(FIXP_DBL *pDat, int size, int *pDat_e);

#endif