sbrdec_drc.cpp - Android社区 - https://www.androidos.net.cn/

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----------------------------------------------------------------------------------------------------------- */

/*****************************  MPEG-4 AAC Decoder  **************************

Author(s):   Christian Griebel
   Description: Dynamic range control (DRC) decoder tool for SBR

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

#include "sbrdec_drc.h"

/* DRC - Offset table for QMF interpolation. */
static const int offsetTab[2][16] =
{
  { 0, 4, 8, 12, 16, 20, 24, 28, 0, 0, 0, 0, 0, 0, 0, 0 },  /* 1024 framing */
  { 0, 4, 8, 12, 16, 19, 22, 26, 0, 0, 0, 0, 0, 0, 0, 0 }   /*  960 framing */
};

/*!
  \brief Initialize DRC QMF factors

\hDrcData Handle to DRC channel data.

\return none
*/
void sbrDecoder_drcInitChannel (
    HANDLE_SBR_DRC_CHANNEL  hDrcData )
{
  int band;

if (hDrcData == NULL) {
    return;
  }

for (band = 0; band < (64); band++) {
    hDrcData->prevFact_mag[band] = FL2FXCONST_DBL(0.5f);
  }

for (band = 0; band < SBRDEC_MAX_DRC_BANDS; band++) {
    hDrcData->currFact_mag[band] = FL2FXCONST_DBL(0.5f);
    hDrcData->nextFact_mag[band] = FL2FXCONST_DBL(0.5f);
  }

hDrcData->prevFact_exp = 1;
  hDrcData->currFact_exp = 1;
  hDrcData->nextFact_exp = 1;

hDrcData->numBandsCurr = 0;
  hDrcData->numBandsNext = 0;

hDrcData->winSequenceCurr = 0;
  hDrcData->winSequenceNext = 0;

hDrcData->drcInterpolationSchemeCurr = 0;
  hDrcData->drcInterpolationSchemeNext = 0;

hDrcData->enable = 0;
}

/*!
  \brief Swap DRC QMF scaling factors after they have been applied.

\hDrcData Handle to DRC channel data.

\return none
*/
void sbrDecoder_drcUpdateChannel (
    HANDLE_SBR_DRC_CHANNEL  hDrcData )
{
  if (hDrcData == NULL) {
    return;
  }
  if (hDrcData->enable != 1) {
    return;
  }

/* swap previous data */
  FDKmemcpy( hDrcData->currFact_mag,
             hDrcData->nextFact_mag,
             SBRDEC_MAX_DRC_BANDS * sizeof(FIXP_DBL) );

hDrcData->currFact_exp = hDrcData->nextFact_exp;

hDrcData->numBandsCurr = hDrcData->numBandsNext;

FDKmemcpy( hDrcData->bandTopCurr,
             hDrcData->bandTopNext,
             SBRDEC_MAX_DRC_BANDS * sizeof(USHORT) );

hDrcData->drcInterpolationSchemeCurr = hDrcData->drcInterpolationSchemeNext;

hDrcData->winSequenceCurr = hDrcData->winSequenceNext;
}

/*!
  \brief Apply DRC factors slot based.

\hDrcData Handle to DRC channel data.
  \qmfRealSlot Pointer to real valued QMF data of one time slot.
  \qmfImagSlot Pointer to the imaginary QMF data of one time slot.
  \col Number of the time slot.
  \numQmfSubSamples Total number of time slots for one frame.
  \scaleFactor Pointer to the out scale factor of the time slot.

\return None.
*/
void sbrDecoder_drcApplySlot (
    HANDLE_SBR_DRC_CHANNEL  hDrcData,
    FIXP_DBL   *qmfRealSlot,
    FIXP_DBL   *qmfImagSlot,
    int  col,
    int  numQmfSubSamples,
    int  maxShift
  )
{
  const int *offset;

int band, bottomMdct, topMdct, bin, useLP;
  int indx = numQmfSubSamples - (numQmfSubSamples >> 1) - 10;   /* l_border */
  int frameLenFlag = (numQmfSubSamples == 30) ? 1 : 0;

const FIXP_DBL *fact_mag = NULL;
  INT fact_exp = 0;
  UINT numBands = 0;
  USHORT *bandTop = NULL;
  int shortDrc = 0;

FIXP_DBL alphaValue = FL2FXCONST_DBL(0.0f);

if (hDrcData == NULL) {
    return;
  }
  if (hDrcData->enable != 1) {
    return;
  }

offset = offsetTab[frameLenFlag];

useLP = (qmfImagSlot == NULL) ? 1 : 0;

col += indx;
  bottomMdct = 0;
  bin = 0;

/* get respective data and calc interpolation factor */
  if (col < (numQmfSubSamples>>1)) {  /* first half of current frame */
    if (hDrcData->winSequenceCurr != 2) { /* long window */
      int j = col + (numQmfSubSamples>>1);

if (hDrcData->drcInterpolationSchemeCurr == 0) {
        INT k = (frameLenFlag) ? 0x4444444 : 0x4000000;

alphaValue = (FIXP_DBL)(j * k);
      }
      else {
        if (j >= offset[hDrcData->drcInterpolationSchemeCurr - 1]) {
          alphaValue = (FIXP_DBL)MAXVAL_DBL;
        }
      }
    }
    else {  /* short windows */
      shortDrc = 1;
    }

fact_mag = hDrcData->currFact_mag;
    fact_exp = hDrcData->currFact_exp;
    numBands = hDrcData->numBandsCurr;
    bandTop = hDrcData->bandTopCurr;
  }
  else if (col < numQmfSubSamples) {  /* second half of current frame */
    if (hDrcData->winSequenceNext != 2) { /* next: long window */
      int j = col - (numQmfSubSamples>>1);

if (hDrcData->drcInterpolationSchemeNext == 0) {
        INT k = (frameLenFlag) ? 0x4444444 : 0x4000000;

alphaValue = (FIXP_DBL)(j * k);
      }
      else {
        if (j >= offset[hDrcData->drcInterpolationSchemeNext - 1]) {
          alphaValue = (FIXP_DBL)MAXVAL_DBL;
        }
      }

fact_mag = hDrcData->nextFact_mag;
      fact_exp = hDrcData->nextFact_exp;
      numBands = hDrcData->numBandsNext;
      bandTop = hDrcData->bandTopNext;
    }
    else {  /* next: short windows */
      if (hDrcData->winSequenceCurr != 2) {  /* current: long window */
        alphaValue = (FIXP_DBL)0;

fact_mag = hDrcData->nextFact_mag;
        fact_exp = hDrcData->nextFact_exp;
        numBands = hDrcData->numBandsNext;
        bandTop = hDrcData->bandTopNext;
      }
      else {  /* current: short windows */
        shortDrc = 1;

fact_mag = hDrcData->currFact_mag;
        fact_exp = hDrcData->currFact_exp;
        numBands = hDrcData->numBandsCurr;
        bandTop = hDrcData->bandTopCurr;
      }
    }
  }
  else {  /* first half of next frame */
    if (hDrcData->winSequenceNext != 2) { /* long window */
      int j = col - (numQmfSubSamples>>1);

if (hDrcData->drcInterpolationSchemeNext == 0) {
        INT k = (frameLenFlag) ? 0x4444444 : 0x4000000;

alphaValue = (FIXP_DBL)(j * k);
      }
      else {
        if (j >= offset[hDrcData->drcInterpolationSchemeNext - 1]) {
          alphaValue = (FIXP_DBL)MAXVAL_DBL;
        }
      }
    }
    else {  /* short windows */
      shortDrc = 1;
    }

fact_mag = hDrcData->nextFact_mag;
    fact_exp = hDrcData->nextFact_exp;
    numBands = hDrcData->numBandsNext;
    bandTop = hDrcData->bandTopNext;

col -= numQmfSubSamples;
  }

/* process bands */
  for (band = 0; band < (int)numBands; band++) {
    int bottomQmf, topQmf;

FIXP_DBL drcFact_mag = (FIXP_DBL)MAXVAL_DBL;

topMdct = (bandTop[band]+1) << 2;

if (!shortDrc) {  /* long window */
      if (frameLenFlag) {
        /* 960 framing */
        bottomMdct = 30 * (bottomMdct / 30);
        topMdct    = 30 * (topMdct / 30);

bottomQmf = fMultIfloor((FIXP_DBL)0x4444444, bottomMdct);
        topQmf    = fMultIfloor((FIXP_DBL)0x4444444, topMdct);
      }
      else {
        /* 1024 framing */
        bottomMdct &= ~0x1f;
        topMdct    &= ~0x1f;

bottomQmf = bottomMdct >> 5;
        topQmf    = topMdct >> 5;
      }

if (band == ((int)numBands-1)) {
        topQmf = (64);
      }
    
      for (bin = bottomQmf; bin < topQmf; bin++) {
        FIXP_DBL drcFact1_mag = hDrcData->prevFact_mag[bin];
        FIXP_DBL drcFact2_mag = fact_mag[band];

/* normalize scale factors */
        if (hDrcData->prevFact_exp < maxShift) {
          drcFact1_mag >>= maxShift - hDrcData->prevFact_exp;
        }
        if (fact_exp < maxShift) {
          drcFact2_mag >>= maxShift - fact_exp;
        }

/* interpolate */
        if (alphaValue == (FIXP_DBL)0) {
          drcFact_mag = drcFact1_mag;
        } else if (alphaValue == (FIXP_DBL)MAXVAL_DBL) {
          drcFact_mag = drcFact2_mag;
        } else {
          drcFact_mag = fMult(alphaValue, drcFact2_mag) + fMult(((FIXP_DBL)MAXVAL_DBL - alphaValue), drcFact1_mag);
        }

/* apply scaling */
        qmfRealSlot[bin] = fMult(qmfRealSlot[bin], drcFact_mag);
        if (!useLP) {
          qmfImagSlot[bin] = fMult(qmfImagSlot[bin], drcFact_mag);
        }

/* save previous factors */
        if (col == (numQmfSubSamples>>1)-1) {
          hDrcData->prevFact_mag[bin] = fact_mag[band];
        }
      }
    }
    else {  /* short windows */
      int startSample, stopSample;
      FIXP_DBL invFrameSizeDiv8 = (frameLenFlag) ? (FIXP_DBL)0x1111111 : (FIXP_DBL)0x1000000;

if (frameLenFlag) {
        /*  960 framing */
        bottomMdct = 30/8 * (bottomMdct*8/30);
        topMdct    = 30/8 * (topMdct*8/30);
      }
      else {
        /* 1024 framing */
        bottomMdct &= ~0x03;
        topMdct    &= ~0x03;
      }

/* startSample is truncated to the nearest corresponding start subsample in
         the QMF of the short window bottom is present in:*/
      startSample  = ((fMultIfloor( invFrameSizeDiv8, bottomMdct ) & 0x7) * numQmfSubSamples) >> 3;

/* stopSample is rounded upwards to the nearest corresponding stop subsample
         in the QMF of the short window top is present in. */
      stopSample  = ((fMultIceil( invFrameSizeDiv8, topMdct ) & 0xf) * numQmfSubSamples) >> 3;

bottomQmf = fMultIfloor( invFrameSizeDiv8, ((bottomMdct%(numQmfSubSamples<<2)) << 5) );
      topQmf    = fMultIfloor( invFrameSizeDiv8, ((topMdct%(numQmfSubSamples<<2)) << 5) );

/* extend last band */
      if (band == ((int)numBands-1)) {
        topQmf = (64);
        stopSample = numQmfSubSamples;
      }

if (topQmf == 0) {
        topQmf = (64);
      }

/* save previous factors */
      if (stopSample == numQmfSubSamples) {
        int tmpBottom = bottomQmf;

if (((numQmfSubSamples-1) & ~0x03) > startSample) {
            tmpBottom = 0;    /* band starts in previous short window */
        }

for (bin = tmpBottom; bin < topQmf; bin++) {
          hDrcData->prevFact_mag[bin] = fact_mag[band];
        }
      }

/* apply */
      if ((col >= startSample) && (col < stopSample)) {
        if ((col & ~0x03) > startSample) {
            bottomQmf = 0;    /* band starts in previous short window */
        }
        if (col < ((stopSample-1) & ~0x03)) {
            topQmf = (64);   /* band ends in next short window */
        }

drcFact_mag = fact_mag[band];

/* normalize scale factor */
        if (fact_exp < maxShift) {
          drcFact_mag >>= maxShift - fact_exp;
        }

/* apply scaling */
        for (bin = bottomQmf; bin < topQmf; bin++) {
          qmfRealSlot[bin] = fMult(qmfRealSlot[bin], drcFact_mag);
          if (!useLP) {
            qmfImagSlot[bin] = fMult(qmfImagSlot[bin], drcFact_mag);
          }
        }
      }
    }

bottomMdct = topMdct;
  }   /* end of bands loop */

if (col == (numQmfSubSamples>>1)-1) {
    hDrcData->prevFact_exp = fact_exp;
  }
}

/*!
  \brief Apply DRC factors frame based.

\hDrcData Handle to DRC channel data.
  \qmfRealSlot Pointer to real valued QMF data of the whole frame.
  \qmfImagSlot Pointer to the imaginary QMF data of the whole frame.
  \numQmfSubSamples Total number of time slots for one frame.
  \scaleFactor Pointer to the out scale factor of the frame.

\return None.
*/
void sbrDecoder_drcApply (
    HANDLE_SBR_DRC_CHANNEL  hDrcData,
    FIXP_DBL **QmfBufferReal,
    FIXP_DBL **QmfBufferImag,
    int  numQmfSubSamples,
    int *scaleFactor
  )
{
  int col;
  int maxShift = 0;

if (hDrcData == NULL) {
    return;
  }
  if ( (hDrcData->enable == 0)
    || ((hDrcData->numBandsCurr == 0) && (hDrcData->numBandsNext == 0))
     ) {
    return;  /* Avoid changing the scaleFactor even though the processing is disabled. */
  }

/* get max scale factor */
  if (hDrcData->prevFact_exp > maxShift) {
    maxShift = hDrcData->prevFact_exp;
  }
  if (hDrcData->currFact_exp > maxShift) {
    maxShift = hDrcData->currFact_exp;
  }
  if (hDrcData->nextFact_exp > maxShift) {
    maxShift = hDrcData->nextFact_exp;
  }

for (col = 0; col < numQmfSubSamples; col++)
  {
    FIXP_DBL *qmfSlotReal = QmfBufferReal[col];
    FIXP_DBL *qmfSlotImag = (QmfBufferImag == NULL) ? NULL : QmfBufferImag[col];

sbrDecoder_drcApplySlot (
      hDrcData,
      qmfSlotReal,
      qmfSlotImag,
      col,
      numQmfSubSamples,
      maxShift
    );
  }

*scaleFactor += maxShift;
}

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