fdk-aac/libAACenc/src/band_nrg.cpp

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

© Copyright  1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
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 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
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with the ISO/IEC MPEG audio standards. Please note that most manufacturers of
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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
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information and documentation.

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Redistribution and use in source and binary forms, with or without modification,
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Fraunhofer provides no warranty of patent non-infringement with respect to this
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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
----------------------------------------------------------------------------- */

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

   Author(s):   M. Werner

   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;

    DWORD_ALIGNED(mdctSpectrum);

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

/*****************************************************************************
  functionname: FDKaacEnc_CheckBandEnergyOptim
  description:
  input:
  output:
*****************************************************************************/
FIXP_DBL
FDKaacEnc_CheckBandEnergyOptim(const FIXP_DBL *const RESTRICT mdctSpectrum,
                               const INT *const RESTRICT sfbMaxScaleSpec,
                               const INT *const RESTRICT bandOffset,
                               const INT numBands,
                               FIXP_DBL *RESTRICT bandEnergy,
                               FIXP_DBL *RESTRICT bandEnergyLdData,
                               const 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;

    DWORD_ALIGNED(mdctSpectrum);

    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] = fMin(NrgMid, (FIXP_DBL)MAXVAL_DBL >> 1) << 1;
    bandEnergySide[i] = fMin(NrgSide, (FIXP_DBL)MAXVAL_DBL >> 1) << 1;
  }

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

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