xref: /aosp_15_r20/external/aac/libAACenc/src/block_switch.h (revision e54365361535b070c2db7374cec45c159c7d0e7a)

/* -----------------------------------------------------------------------------
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
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of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec Library for Android"
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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,
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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
[email protected]
----------------------------------------------------------------------------- */

/**************************** AAC encoder library ******************************

   Author(s):   M. Werner

   Description: Block switching

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

#ifndef BLOCK_SWITCH_H
#define BLOCK_SWITCH_H

#include "common_fix.h"

#include "psy_const.h"

/****************** Defines ******************************/
#define BLOCK_SWITCH_WINDOWS 8 /* number of windows for energy calculation */

#define BLOCK_SWITCHING_IIR_LEN \
  2 /* Length of HighPass-IIR-Filter for Attack-Detection */
#define BLOCK_SWITCH_ENERGY_SHIFT                                        \
  7 /* should be logDualis(BLOCK_SWITCH_WINDOW_LEN) to avoid overflow in \
       windowNrgs. */

#define LAST_WINDOW 0
#define THIS_WINDOW 1

/****************** Structures ***************************/
typedef struct {
  INT lastWindowSequence;
  INT windowShape;
  INT lastWindowShape;
  UINT nBlockSwitchWindows; /* number of windows for energy calculation */
  INT attack;
  INT lastattack;
  INT attackIndex;
  INT lastAttackIndex;
  INT allowShortFrames; /* for Low Delay, don't allow short frames */
  INT allowLookAhead;   /* for Low Delay, don't do look-ahead */
  INT noOfGroups;
  INT groupLen[MAX_NO_OF_GROUPS];
  FIXP_DBL maxWindowNrg; /* max energy in subwindows */

  FIXP_DBL
  windowNrg[2][BLOCK_SWITCH_WINDOWS]; /* time signal energy in Subwindows
                                         (last and current) */
  FIXP_DBL windowNrgF[2][BLOCK_SWITCH_WINDOWS]; /* filtered time signal energy
                                                   in segments (last and
                                                   current) */
  FIXP_DBL accWindowNrg; /* recursively accumulated windowNrgF */

  FIXP_DBL iirStates[BLOCK_SWITCHING_IIR_LEN]; /* filter delay-line */

} BLOCK_SWITCHING_CONTROL;

void FDKaacEnc_InitBlockSwitching(
    BLOCK_SWITCHING_CONTROL *blockSwitchingControl, INT isLowDelay);

int FDKaacEnc_BlockSwitching(BLOCK_SWITCHING_CONTROL *blockSwitchingControl,
                             const INT granuleLength, const int isLFE,
                             const INT_PCM *pTimeSignal);

int FDKaacEnc_SyncBlockSwitching(
    BLOCK_SWITCHING_CONTROL *blockSwitchingControlLeft,
    BLOCK_SWITCHING_CONTROL *blockSwitchingControlRight, const INT noOfChannels,
    const INT commonWindow);

#endif /* #ifndef BLOCK_SWITCH_H */