block_switch.h - Android社区 - https://www.androidos.net.cn/

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

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
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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
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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.

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You must make available free of charge copies of the complete source code of the FDK AAC Codec and your
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This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors
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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
----------------------------------------------------------------------------------------------------------- */

/*****************************  MPEG-4 AAC Encoder  **************************

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_PCM *timeSignal;
  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);

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

#endif  /* #ifndef _BLOCK_SWITCH_H */

C++程序 | 148行 | 6.86 KB

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