xref: /aosp_15_r20/external/aac/libFDK/include/mdct.h (revision e54365361535b070c2db7374cec45c159c7d0e7a)

/* -----------------------------------------------------------------------------
Software License for The Fraunhofer FDK AAC Codec Library for Android

© Copyright  1995 - 2019 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
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however caused and on any theory of liability, whether in contract, strict
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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
[email protected]
----------------------------------------------------------------------------- */

/******************* Library for basic calculation routines ********************

   Author(s):   Manuel Jander, Josef Hoepfl, Youliy Ninov, Daniel Hagel

   Description: MDCT/MDST routines

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

#ifndef MDCT_H
#define MDCT_H

#include "common_fix.h"

#define MDCT_OUT_HEADROOM 2 /* Output additional headroom */

#define PCM_OUT_BITS DFRACT_BITS
#define PCM_OUT_HEADROOM 8 /* Must have the same values as DMXH_HEADROOM */

#define MDCT_OUTPUT_SCALE (-MDCT_OUT_HEADROOM + (DFRACT_BITS - PCM_OUT_BITS))
/* Refer to "Output word length" in ISO/IEC 14496-3:2008(E) 23.2.3.6 */
#define MDCT_OUTPUT_GAIN 16

#define IMDCT_SCALE(x, s) \
  SATURATE_RIGHT_SHIFT((x), ((s) + MDCT_OUTPUT_SCALE), PCM_OUT_BITS)
#define IMDCT_SCALE_DBL(x) (FIXP_DBL)(x)
#define IMDCT_SCALE_DBL_LSH1(x) SATURATE_LEFT_SHIFT_ALT((x), 1, DFRACT_BITS)

#define MLT_FLAG_CURR_ALIAS_SYMMETRY 1

typedef enum {
  BLOCK_LONG = 0, /* normal long block */
  BLOCK_START,    /* long start block */
  BLOCK_SHORT,    /* 8 short blocks sequence */
  BLOCK_STOP      /* long stop block*/
} BLOCK_TYPE;

typedef enum { SHAPE_SINE = 0, SHAPE_KBD, SHAPE_LOL } WINDOW_SHAPE;

/**
 * \brief MDCT persistent data
 */
typedef struct {
  union {
    FIXP_DBL *freq;
    FIXP_DBL *time;
  } overlap; /**< Pointer to overlap memory */

  const FIXP_WTP *prev_wrs; /**< pointer to previous right window slope  */
  int prev_tl;              /**< previous transform length */
  int prev_nr;              /**< previous right window offset */
  int prev_fr;              /**< previous right window slope length */
  int ov_offset;            /**< overlap time data fill level */
  int ov_size;              /**< Overlap buffer size in words */

  int prevAliasSymmetry;
  int prevPrevAliasSymmetry;

  FIXP_DBL *pFacZir;
  FIXP_DBL *pAsymOvlp; /**< pointer to asymmetric overlap (used for stereo LPD
                          transition) */
} mdct_t;

typedef mdct_t *H_MDCT;

/**
 * \brief Initialize as valid MDCT handle
 *
 * \param hMdct handle of an allocated MDCT handle.
 * \param overlap pointer to FIXP_DBL overlap buffer.
 * \param overlapBufferSize size in FIXP_DBLs of the given overlap buffer.
 */
void mdct_init(H_MDCT hMdct, FIXP_DBL *overlap, INT overlapBufferSize);

/**
 * \brief perform MDCT transform (time domain to frequency domain) with given
 * parameters.
 *
 * \param hMdct handle of an allocated MDCT handle.
 * \param pTimeData pointer to input time domain signal
 * \param noInSamples number of input samples
 * \param mdctData pointer to where the resulting MDCT spectrum will be stored
 * into.
 * \param nSpec number of spectra
 * \param pMdctData_e pointer to the input data exponent. Updated accordingly on
 * return for output data.
 * \return number of input samples processed.
 */
INT mdct_block(H_MDCT hMdct, const INT_PCM *pTimeData, const INT noInSamples,
               FIXP_DBL *RESTRICT mdctData, const INT nSpec, const INT tl,
               const FIXP_WTP *pRightWindowPart, const INT fr,
               SHORT *pMdctData_e);

/**
 * \brief add/multiply 2/N transform gain and MPEG4 part 3 defined output gain
 * (see definition of MDCT_OUTPUT_GAIN) to given mantissa factor and exponent.
 * \param pGain pointer to the mantissa of a gain factor to be applied to IMDCT
 * data.
 * \param pExponent pointer to the exponent of a gain factor to be applied to
 * IMDCT data.
 * \param tl length of the IMDCT where the gain *pGain * (2 ^ *pExponent) will
 * be applied to.
 */
void imdct_gain(FIXP_DBL *pGain, int *pExponent, int tl);

/**
 * \brief drain buffered output samples into given buffer. Changes the MDCT
 * state.
 */
INT imdct_drain(H_MDCT hMdct, FIXP_DBL *pTimeData, INT nrSamplesRoom);

/**
 * \brief Copy overlap time domain data to given buffer. Does not change the
 * MDCT state.
 * \return number of actually copied samples (ov + nr).
 */
INT imdct_copy_ov_and_nr(H_MDCT hMdct, FIXP_DBL *pTimeData, INT nrSamples);

/**
 * \brief Adapt MDCT parameters for non-matching window slopes.
 * \param hMdct handle of an allocated MDCT handle.
 * \param pfl pointer to left overlap window side length.
 * \param pnl pointer to length of the left n part of the window.
 * \param tl transform length.
 * \param wls pointer to the left side overlap window coefficients.
 * \param noOutSamples desired number of output samples.
 */
void imdct_adapt_parameters(H_MDCT hMdct, int *pfl, int *pnl, int tl,
                            const FIXP_WTP *wls, int noOutSamples);

/**
 * \brief perform several inverse MLT transforms (frequency domain to time
 * domain) with given parameters.
 *
 * \param hMdct handle of an allocated MDCT handle.
 * \param output pointer to where the output time domain signal will be stored
 * into.
 * \param spectrum pointer to the input MDCT spectra.
 * \param scalefactors exponents of the input spectrum.
 * \param nSpec number of MDCT spectrums.
 * \param noOutSamples desired number of output samples.
 * \param tl transform length.
 * \param wls pointer to the left side overlap window coefficients.
 * \param fl left overlap window side length.
 * \param wrs pointer to the right side overlap window coefficients of all
 * individual IMDCTs.
 * \param fr right overlap window side length of all individual IMDCTs.
 * \param gain factor to apply to output samples (if != 0).
 * \param flags flags controlling the type of transform
 * \return number of output samples returned.
 */
INT imlt_block(H_MDCT hMdct, FIXP_DBL *output, FIXP_DBL *spectrum,
               const SHORT scalefactor[], const INT nSpec,
               const INT noOutSamples, const INT tl, const FIXP_WTP *wls,
               INT fl, const FIXP_WTP *wrs, const INT fr, FIXP_DBL gain,
               int flags);

#endif /* MDCT_H */