spreading.cpp - 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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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
"AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the 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
----------------------------------------------------------------------------------------------------------- */

/******************************** MPEG Audio Encoder **************************

Initial author:       M.Werner
   contents/description: Spreading of energy

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

#include "spreading.h"

void FDKaacEnc_SpreadingMax(const INT       pbCnt,
                            const FIXP_DBL  *RESTRICT maskLowFactor,
                            const FIXP_DBL  *RESTRICT maskHighFactor,
                            FIXP_DBL        *RESTRICT pbSpreadEnergy)
{
   int i;
   FIXP_DBL delay;

/* slope to higher frequencies */
   delay = pbSpreadEnergy[0];
   for (i=1; i<pbCnt; i++) {
      delay = fixMax(pbSpreadEnergy[i], fMult(maskHighFactor[i], delay));
      pbSpreadEnergy[i] = delay;
   }

/* slope to lower frequencies */
   delay = pbSpreadEnergy[pbCnt-1];
   for (i=pbCnt-2; i>=0; i--) {
      delay = fixMax(pbSpreadEnergy[i], fMult(maskLowFactor[i],delay));
      pbSpreadEnergy[i] = delay;
   }
}

C++程序 | 115行 | 5.52 KB

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