quantize.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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You must retain the complete text of this software license in redistributions of the FDK AAC Codec or
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You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized
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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: Quantization

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

#include "quantize.h"

#include "aacEnc_rom.h"

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

functionname: FDKaacEnc_quantizeLines
    description: quantizes spectrum lines
    returns:
    input: global gain, number of lines to process, spectral data
    output: quantized spectrum

*****************************************************************************/
static void FDKaacEnc_quantizeLines(INT      gain,
                          INT      noOfLines,
                          FIXP_DBL *mdctSpectrum,
                          SHORT      *quaSpectrum)
{
  int   line;
  FIXP_DBL k = FL2FXCONST_DBL(-0.0946f + 0.5f)>>16;
  FIXP_QTD quantizer = FDKaacEnc_quantTableQ[(-gain)&3];
  INT      quantizershift = ((-gain)>>2)+1;

for (line = 0; line < noOfLines; line++)
  {
    FIXP_DBL accu = fMultDiv2(mdctSpectrum[line],quantizer);

if (accu < FL2FXCONST_DBL(0.0f))
    {
      accu=-accu;
      /* normalize */
      INT   accuShift = CntLeadingZeros(accu) - 1;  /* CountLeadingBits() is not necessary here since test value is always > 0 */
      accu <<= accuShift;
      INT tabIndex = (INT)(accu>>(DFRACT_BITS-2-MANT_DIGITS))&(~MANT_SIZE);
      INT totalShift = quantizershift-accuShift+1;
      accu = fMultDiv2(FDKaacEnc_mTab_3_4[tabIndex],FDKaacEnc_quantTableE[totalShift&3]);
      totalShift = (16-4)-(3*(totalShift>>2));
      FDK_ASSERT(totalShift >=0); /* MAX_QUANT_VIOLATION */
      accu >>= fixMin(totalShift,DFRACT_BITS-1);
      quaSpectrum[line] = (SHORT)(-((LONG)(k + accu) >> (DFRACT_BITS-1-16)));
    }
    else if(accu > FL2FXCONST_DBL(0.0f))
    {
      /* normalize */
      INT   accuShift = CntLeadingZeros(accu) - 1;  /* CountLeadingBits() is not necessary here since test value is always > 0 */
      accu <<= accuShift;
      INT tabIndex = (INT)(accu>>(DFRACT_BITS-2-MANT_DIGITS))&(~MANT_SIZE);
      INT totalShift = quantizershift-accuShift+1;
      accu = fMultDiv2(FDKaacEnc_mTab_3_4[tabIndex],FDKaacEnc_quantTableE[totalShift&3]);
      totalShift = (16-4)-(3*(totalShift>>2));
      FDK_ASSERT(totalShift >=0); /* MAX_QUANT_VIOLATION */
      accu >>= fixMin(totalShift,DFRACT_BITS-1);
      quaSpectrum[line] = (SHORT)((LONG)(k + accu) >> (DFRACT_BITS-1-16));
    }
    else
      quaSpectrum[line]=0;
  }
}

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

functionname:iFDKaacEnc_quantizeLines
    description: iquantizes spectrum lines
                 mdctSpectrum = iquaSpectrum^4/3 *2^(0.25*gain)
    input: global gain, number of lines to process,quantized spectrum
    output: spectral data

*****************************************************************************/
static void FDKaacEnc_invQuantizeLines(INT  gain,
                             INT  noOfLines,
                             SHORT *quantSpectrum,
                             FIXP_DBL *mdctSpectrum)

{
  INT iquantizermod;
  INT iquantizershift;
  INT line;

iquantizermod = gain&3;
  iquantizershift = gain>>2;

for (line = 0; line < noOfLines; line++) {

if(quantSpectrum[line] < 0) {
      FIXP_DBL accu;
      INT ex,specExp,tabIndex;
      FIXP_DBL s,t;

accu = (FIXP_DBL) -quantSpectrum[line];

ex = CountLeadingBits(accu);
      accu <<= ex;
      specExp = (DFRACT_BITS-1) - ex;

FDK_ASSERT(specExp < 14);       /* this fails if abs(value) > 8191 */

tabIndex = (INT)(accu>>(DFRACT_BITS-2-MANT_DIGITS))&(~MANT_SIZE);

/* calculate "mantissa" ^4/3 */
      s = FDKaacEnc_mTab_4_3Elc[tabIndex];

/* get approperiate exponent multiplier for specExp^3/4 combined with scfMod */
      t = FDKaacEnc_specExpMantTableCombElc[iquantizermod][specExp];

/* multiply "mantissa" ^4/3 with exponent multiplier */
      accu = fMult(s,t);

/* get approperiate exponent shifter */
      specExp = FDKaacEnc_specExpTableComb[iquantizermod][specExp]-1; /* -1 to avoid overflows in accu */

if ((-iquantizershift-specExp) < 0)
        accu <<= -(-iquantizershift-specExp);
      else
        accu >>= -iquantizershift-specExp;

mdctSpectrum[line] = -accu;
    }
    else if (quantSpectrum[line] > 0) {
      FIXP_DBL accu;
      INT ex,specExp,tabIndex;
      FIXP_DBL s,t;

accu = (FIXP_DBL)(INT)quantSpectrum[line];

ex = CountLeadingBits(accu);
      accu <<= ex;
      specExp = (DFRACT_BITS-1) - ex;

FDK_ASSERT(specExp < 14);       /* this fails if abs(value) > 8191 */

tabIndex = (INT)(accu>>(DFRACT_BITS-2-MANT_DIGITS))&(~MANT_SIZE);

/* calculate "mantissa" ^4/3 */
      s = FDKaacEnc_mTab_4_3Elc[tabIndex];

/* get approperiate exponent multiplier for specExp^3/4 combined with scfMod */
      t = FDKaacEnc_specExpMantTableCombElc[iquantizermod][specExp];

/* multiply "mantissa" ^4/3 with exponent multiplier */
      accu = fMult(s,t);

/* get approperiate exponent shifter */
      specExp = FDKaacEnc_specExpTableComb[iquantizermod][specExp]-1; /* -1 to avoid overflows in accu */

if (( -iquantizershift-specExp) < 0)
        accu <<= -(-iquantizershift-specExp);
      else
        accu >>= -iquantizershift-specExp;

mdctSpectrum[line] = accu;
    }
    else {
      mdctSpectrum[line] = FL2FXCONST_DBL(0.0f);
    }
  }
}

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

functionname: FDKaacEnc_QuantizeSpectrum
    description: quantizes the entire spectrum
    returns:
    input: number of scalefactor bands to be quantized, ...
    output: quantized spectrum

*****************************************************************************/
void FDKaacEnc_QuantizeSpectrum(INT sfbCnt,
                      INT maxSfbPerGroup,
                      INT sfbPerGroup,
                      INT *sfbOffset,
                      FIXP_DBL *mdctSpectrum,
                      INT globalGain,
                      INT *scalefactors,
                      SHORT *quantizedSpectrum)
{
  INT sfbOffs,sfb;

/* in FDKaacEnc_quantizeLines quaSpectrum is calculated with:
        spec^(3/4) * 2^(-3/16*QSS) * 2^(3/4*scale) + k
     simplify scaling calculation and reduce QSS before:
        spec^(3/4) * 2^(-3/16*(QSS - 4*scale)) */

for(sfbOffs=0;sfbOffs<sfbCnt;sfbOffs+=sfbPerGroup)
  for (sfb = 0; sfb < maxSfbPerGroup; sfb++)
  {
    INT scalefactor = scalefactors[sfbOffs+sfb] ;

FDKaacEnc_quantizeLines(globalGain - scalefactor, /* QSS */
                  sfbOffset[sfbOffs+sfb+1] - sfbOffset[sfbOffs+sfb],
                  mdctSpectrum + sfbOffset[sfbOffs+sfb],
                  quantizedSpectrum + sfbOffset[sfbOffs+sfb]);
  }
}

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

functionname: FDKaacEnc_calcSfbDist
    description: calculates distortion of quantized values
    returns: distortion
    input: gain, number of lines to process, spectral data
    output:

*****************************************************************************/
FIXP_DBL FDKaacEnc_calcSfbDist(FIXP_DBL *mdctSpectrum,
                     SHORT *quantSpectrum,
                     INT noOfLines,
                     INT gain
                     )
{
  INT i,scale;
  FIXP_DBL xfsf;
  FIXP_DBL diff;
  FIXP_DBL invQuantSpec;

xfsf = FL2FXCONST_DBL(0.0f);

for (i=0; i<noOfLines; i++) {
    /* quantization */
    FDKaacEnc_quantizeLines(gain,
                  1,
                 &mdctSpectrum[i],
                 &quantSpectrum[i]);

if (fAbs(quantSpectrum[i])>MAX_QUANT) {
      return FL2FXCONST_DBL(0.0f);
    }
    /* inverse quantization */
    FDKaacEnc_invQuantizeLines(gain,1,&quantSpectrum[i],&invQuantSpec);

/* dist */
    diff = fixp_abs(fixp_abs(invQuantSpec) - fixp_abs(mdctSpectrum[i]>>1));

scale = CountLeadingBits(diff);
    diff = scaleValue(diff, scale);
    diff = fPow2(diff);
    scale = fixMin(2*(scale-1), DFRACT_BITS-1);

diff = scaleValue(diff, -scale);

xfsf = xfsf + diff;
  }

xfsf = CalcLdData(xfsf);

return xfsf;
}

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

functionname: FDKaacEnc_calcSfbQuantEnergyAndDist
    description: calculates energy and distortion of quantized values
    returns:
    input: gain, number of lines to process, quantized spectral data,
           spectral data
    output: energy, distortion

*****************************************************************************/
void FDKaacEnc_calcSfbQuantEnergyAndDist(FIXP_DBL *mdctSpectrum,
                               SHORT *quantSpectrum,
                               INT noOfLines,
                               INT gain,
                               FIXP_DBL *en,
                               FIXP_DBL *dist)
{
  INT i,scale;
  FIXP_DBL invQuantSpec;
  FIXP_DBL diff;

FIXP_DBL energy = FL2FXCONST_DBL(0.0f);
  FIXP_DBL distortion = FL2FXCONST_DBL(0.0f);

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

if (fAbs(quantSpectrum[i])>MAX_QUANT) {
      *en   = FL2FXCONST_DBL(0.0f);
      *dist = FL2FXCONST_DBL(0.0f);
      return;
    }

/* inverse quantization */
    FDKaacEnc_invQuantizeLines(gain,1,&quantSpectrum[i],&invQuantSpec);

/* energy */
    energy += fPow2(invQuantSpec);

/* dist */
    diff = fixp_abs(fixp_abs(invQuantSpec) - fixp_abs(mdctSpectrum[i]>>1));

scale = CountLeadingBits(diff);
    diff = scaleValue(diff, scale);
    diff = fPow2(diff);

scale = fixMin(2*(scale-1), DFRACT_BITS-1);

diff = scaleValue(diff, -scale);

distortion += diff;
  }

*en   = CalcLdData(energy)+FL2FXCONST_DBL(0.03125f);
  *dist = CalcLdData(distortion);
}

C++程序 | 396行 | 14.15 KB

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