libAACenc/src/band_nrg.cpp

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

� Copyright  1995 - 2013 Fraunhofer-Gesellschaft zur F�rderung 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
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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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Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software
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"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."

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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
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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
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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  **************************

   Initial author:       M. Werner
   contents/description: Band/Line energy calculations

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

#include "band_nrg.h"


/*****************************************************************************
  functionname: FDKaacEnc_CalcSfbMaxScaleSpec
  description:
  input:
  output:
*****************************************************************************/
void
FDKaacEnc_CalcSfbMaxScaleSpec(const FIXP_DBL *RESTRICT mdctSpectrum,
                              const INT      *RESTRICT bandOffset,
                              INT            *RESTRICT sfbMaxScaleSpec,
                              const INT       numBands)
{
  INT i,j;
  FIXP_DBL maxSpc, tmp;

  for(i=0; i<numBands; i++) {
    maxSpc = (FIXP_DBL)0;
    for (j=bandOffset[i]; j<bandOffset[i+1]; j++) {
      tmp = fixp_abs(mdctSpectrum[j]);
      maxSpc = fixMax(maxSpc, tmp);
    }
    sfbMaxScaleSpec[i] = (maxSpc==(FIXP_DBL)0) ? (DFRACT_BITS-2) : CntLeadingZeros(maxSpc)-1;
    /* CountLeadingBits() is not necessary here since test value is always > 0 */
  }
}

/*****************************************************************************
  functionname: FDKaacEnc_CheckBandEnergyOptim
  description:
  input:
  output:
*****************************************************************************/
FIXP_DBL
FDKaacEnc_CheckBandEnergyOptim(const FIXP_DBL *RESTRICT mdctSpectrum,
                               INT            *RESTRICT sfbMaxScaleSpec,
                               const INT      *RESTRICT bandOffset,
                               const INT       numBands,
                               FIXP_DBL       *RESTRICT bandEnergy,
                               FIXP_DBL       *RESTRICT bandEnergyLdData,
                               INT             minSpecShift)
{
  INT i, j, scale, nr = 0;
  FIXP_DBL maxNrgLd = FL2FXCONST_DBL(-1.0f);
  FIXP_DBL maxNrg = 0;
  FIXP_DBL spec;

  for(i=0; i<numBands; i++) {
    scale = fixMax(0, sfbMaxScaleSpec[i]-4);
    FIXP_DBL tmp = 0;
    for (j=bandOffset[i]; j<bandOffset[i+1]; j++){
       spec = mdctSpectrum[j]<<scale;
       tmp = fPow2AddDiv2(tmp, spec);
    }
    bandEnergy[i] = tmp<<1;

    /* calculate ld of bandNrg, subtract scaling */
    bandEnergyLdData[i] = CalcLdData(bandEnergy[i]);
    if (bandEnergyLdData[i] != FL2FXCONST_DBL(-1.0f)) {
      bandEnergyLdData[i] -= scale*FL2FXCONST_DBL(2.0/64);
    }
    /* find index of maxNrg */
    if (bandEnergyLdData[i] > maxNrgLd) {
        maxNrgLd = bandEnergyLdData[i];
        nr = i;
    }
  }

  /* return unscaled maxNrg*/
  scale = fixMax(0,sfbMaxScaleSpec[nr]-4);
  scale = fixMax(2*(minSpecShift-scale),-(DFRACT_BITS-1));

  maxNrg = scaleValue(bandEnergy[nr], scale);

  return maxNrg;
}

/*****************************************************************************
  functionname: FDKaacEnc_CalcBandEnergyOptimLong
  description:
  input:
  output:
*****************************************************************************/
INT
FDKaacEnc_CalcBandEnergyOptimLong(const FIXP_DBL *RESTRICT mdctSpectrum,
                                  INT            *RESTRICT sfbMaxScaleSpec,
                                  const INT      *RESTRICT bandOffset,
                                  const INT       numBands,
                                  FIXP_DBL       *RESTRICT bandEnergy,
                                  FIXP_DBL       *RESTRICT bandEnergyLdData)
{
  INT i, j, shiftBits = 0;
  FIXP_DBL maxNrgLd = FL2FXCONST_DBL(0.0f);

  FIXP_DBL spec;

  for(i=0; i<numBands; i++) {
     INT leadingBits = sfbMaxScaleSpec[i]-4;            /* max sfbWidth = 96 ; 2^7=128 => 7/2 = 4 (spc*spc) */
     FIXP_DBL tmp = FL2FXCONST_DBL(0.0);
     /* don't use scaleValue() here, it increases workload quite sufficiently... */
     if (leadingBits>=0) {
        for (j=bandOffset[i];j<bandOffset[i+1];j++) {
           spec = mdctSpectrum[j]<<leadingBits;
           tmp = fPow2AddDiv2(tmp, spec);
        }
     } else {
        INT shift = -leadingBits;
        for (j=bandOffset[i];j<bandOffset[i+1];j++){
           spec = mdctSpectrum[j]>>shift;
           tmp = fPow2AddDiv2(tmp, spec);
        }
     }
     bandEnergy[i] = tmp<<1;
  }

  /* calculate ld of bandNrg, subtract scaling */
  LdDataVector(bandEnergy, bandEnergyLdData, numBands);
  for(i=numBands; i--!=0; ) {
      FIXP_DBL scaleDiff = (sfbMaxScaleSpec[i]-4)*FL2FXCONST_DBL(2.0/64);

      bandEnergyLdData[i] = (bandEnergyLdData[i] >= ((FL2FXCONST_DBL(-1.f)>>1) + (scaleDiff>>1)))
                          ? bandEnergyLdData[i]-scaleDiff : FL2FXCONST_DBL(-1.f);
      /* find maxNrgLd */
      maxNrgLd = fixMax(maxNrgLd, bandEnergyLdData[i]);
  }

  if (maxNrgLd<=(FIXP_DBL)0)
  {
     for(i=numBands; i--!=0; )
     {
         INT scale = fixMin((sfbMaxScaleSpec[i]-4)<<1,(DFRACT_BITS-1));
         bandEnergy[i] = scaleValue(bandEnergy[i], -scale);
     }
     return 0;
  }
  else
  {  /* scale down NRGs */
     while (maxNrgLd>FL2FXCONST_DBL(0.0f))
     {
        maxNrgLd -=  FL2FXCONST_DBL(2.0/64);
        shiftBits++;
     }
     for(i=numBands; i--!=0; )
     {
         INT scale = fixMin( ((sfbMaxScaleSpec[i]-4)+shiftBits)<<1, (DFRACT_BITS-1));
         bandEnergyLdData[i] -= shiftBits*FL2FXCONST_DBL(2.0/64);
         bandEnergy[i] = scaleValue(bandEnergy[i], -scale);
     }
     return shiftBits;
  }
}


/*****************************************************************************
  functionname: FDKaacEnc_CalcBandEnergyOptimShort
  description:
  input:
  output:
*****************************************************************************/
void
FDKaacEnc_CalcBandEnergyOptimShort(const FIXP_DBL *RESTRICT mdctSpectrum,
                                   INT            *RESTRICT sfbMaxScaleSpec,
                                   const INT      *RESTRICT bandOffset,
                                   const INT       numBands,
                                   FIXP_DBL       *RESTRICT bandEnergy)
{
  INT i, j;

  for(i=0; i<numBands; i++)
  {
    int leadingBits = sfbMaxScaleSpec[i]-3;            /* max sfbWidth = 36 ; 2^6=64 => 6/2 = 3 (spc*spc) */
    FIXP_DBL tmp = FL2FXCONST_DBL(0.0);
    for (j=bandOffset[i];j<bandOffset[i+1];j++)
    {
       FIXP_DBL spec = scaleValue(mdctSpectrum[j],leadingBits);
       tmp = fPow2AddDiv2(tmp, spec);
    }
    bandEnergy[i] = tmp;
  }

  for(i=0; i<numBands; i++)
  {
      INT scale = (2*(sfbMaxScaleSpec[i]-3))-1;         /* max sfbWidth = 36 ; 2^6=64 => 6/2 = 3 (spc*spc) */
      scale = fixMax(fixMin(scale,(DFRACT_BITS-1)),-(DFRACT_BITS-1));
      bandEnergy[i] = scaleValueSaturate(bandEnergy[i], -scale);
  }
}


/*****************************************************************************
  functionname: FDKaacEnc_CalcBandNrgMSOpt
  description:
  input:
  output:
*****************************************************************************/
void FDKaacEnc_CalcBandNrgMSOpt(const FIXP_DBL   *RESTRICT mdctSpectrumLeft,
                                const FIXP_DBL   *RESTRICT mdctSpectrumRight,
                                INT              *RESTRICT sfbMaxScaleSpecLeft,
                                INT              *RESTRICT sfbMaxScaleSpecRight,
                                const INT        *RESTRICT bandOffset,
                                const INT         numBands,
                                FIXP_DBL         *RESTRICT bandEnergyMid,
                                FIXP_DBL         *RESTRICT bandEnergySide,
                                INT               calcLdData,
                                FIXP_DBL         *RESTRICT bandEnergyMidLdData,
                                FIXP_DBL         *RESTRICT bandEnergySideLdData)
{
  INT i, j, minScale;
  FIXP_DBL NrgMid, NrgSide, specm, specs;

  for (i=0; i<numBands; i++) {

    NrgMid = NrgSide = FL2FXCONST_DBL(0.0);
    minScale = fixMin(sfbMaxScaleSpecLeft[i], sfbMaxScaleSpecRight[i])-4;
    minScale = fixMax(0, minScale);

    if (minScale > 0) {
      for (j=bandOffset[i];j<bandOffset[i+1];j++) {
          FIXP_DBL specL = mdctSpectrumLeft[j]<<(minScale-1);
          FIXP_DBL specR = mdctSpectrumRight[j]<<(minScale-1);
          specm = specL + specR;
          specs = specL - specR;
          NrgMid = fPow2AddDiv2(NrgMid, specm);
          NrgSide = fPow2AddDiv2(NrgSide, specs);
      }
    } else {
      for (j=bandOffset[i];j<bandOffset[i+1];j++) {
          FIXP_DBL specL = mdctSpectrumLeft[j]>>1;
          FIXP_DBL specR = mdctSpectrumRight[j]>>1;
          specm = specL + specR;
          specs = specL - specR;
          NrgMid = fPow2AddDiv2(NrgMid, specm);
          NrgSide = fPow2AddDiv2(NrgSide, specs);
      }
    }
    bandEnergyMid[i] = NrgMid<<1;
    bandEnergySide[i] = NrgSide<<1;
  }

  if(calcLdData) {
    LdDataVector(bandEnergyMid, bandEnergyMidLdData, numBands);
    LdDataVector(bandEnergySide, bandEnergySideLdData, numBands);
  }

  for (i=0; i<numBands; i++)
  {
    INT minScale = fixMin(sfbMaxScaleSpecLeft[i], sfbMaxScaleSpecRight[i]);
    INT scale = fixMax(0, 2*(minScale-4));

    if (calcLdData)
    {
       /* using the minimal scaling of left and right channel can cause very small energies;
       check ldNrg before subtract scaling multiplication: fract*INT we don't need fMult */

       int minus = scale*FL2FXCONST_DBL(1.0/64);

       if (bandEnergyMidLdData[i] != FL2FXCONST_DBL(-1.0f))
         bandEnergyMidLdData[i] -= minus;

       if (bandEnergySideLdData[i] != FL2FXCONST_DBL(-1.0f))
         bandEnergySideLdData[i] -= minus;
    }
    scale = fixMin(scale, (DFRACT_BITS-1));
    bandEnergyMid[i]  >>= scale;
    bandEnergySide[i] >>= scale;
  }
}