xref: /aosp_15_r20/external/aac/libSBRenc/src/nf_est.cpp (revision e54365361535b070c2db7374cec45c159c7d0e7a)

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

© Copyright  1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
Forschung e.V. All rights reserved.

 1.    INTRODUCTION
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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
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Commercially-licensed AAC software libraries, including floating-point versions
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Attention: Audio and Multimedia Departments - FDK AAC LL
Am Wolfsmantel 33
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www.iis.fraunhofer.de/amm
[email protected]
----------------------------------------------------------------------------- */

/**************************** SBR encoder library ******************************

   Author(s):

   Description:

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

#include "nf_est.h"

#include "sbr_misc.h"

#include "genericStds.h"

/* smoothFilter[4]  = {0.05857864376269f, 0.2f, 0.34142135623731f, 0.4f}; */
static const FIXP_DBL smoothFilter[4] = {0x077f813d, 0x19999995, 0x2bb3b1f5,
                                         0x33333335};

/* static const INT smoothFilterLength = 4; */

static const FIXP_DBL QuantOffset = (INT)0xfc000000; /* ld64(0.25) */

#ifndef min
#define min(a, b) (a < b ? a : b)
#endif

#ifndef max
#define max(a, b) (a > b ? a : b)
#endif

#define NOISE_FLOOR_OFFSET_SCALING (4)

/**************************************************************************/
/*!
  \brief     The function applies smoothing to the noise levels.



  \return    none

*/
/**************************************************************************/
static void smoothingOfNoiseLevels(
    FIXP_DBL *NoiseLevels, /*!< pointer to noise-floor levels.*/
    INT nEnvelopes,        /*!< Number of noise floor envelopes.*/
    INT noNoiseBands, /*!< Number of noise bands for every noise floor envelope.
                       */
    FIXP_DBL prevNoiseLevels[NF_SMOOTHING_LENGTH]
                            [MAX_NUM_NOISE_VALUES], /*!< Previous noise floor
                                                       envelopes. */
    const FIXP_DBL *
        pSmoothFilter, /*!< filter used for smoothing the noise floor levels. */
    INT transientFlag) /*!< flag indicating if a transient is present*/

{
  INT i, band, env;
  FIXP_DBL accu;

  for (env = 0; env < nEnvelopes; env++) {
    if (transientFlag) {
      for (i = 0; i < NF_SMOOTHING_LENGTH; i++) {
        FDKmemcpy(prevNoiseLevels[i], NoiseLevels + env * noNoiseBands,
                  noNoiseBands * sizeof(FIXP_DBL));
      }
    } else {
      for (i = 1; i < NF_SMOOTHING_LENGTH; i++) {
        FDKmemcpy(prevNoiseLevels[i - 1], prevNoiseLevels[i],
                  noNoiseBands * sizeof(FIXP_DBL));
      }
      FDKmemcpy(prevNoiseLevels[NF_SMOOTHING_LENGTH - 1],
                NoiseLevels + env * noNoiseBands,
                noNoiseBands * sizeof(FIXP_DBL));
    }

    for (band = 0; band < noNoiseBands; band++) {
      accu = FL2FXCONST_DBL(0.0f);
      for (i = 0; i < NF_SMOOTHING_LENGTH; i++) {
        accu += fMultDiv2(pSmoothFilter[i], prevNoiseLevels[i][band]);
      }
      FDK_ASSERT((band + env * noNoiseBands) < MAX_NUM_NOISE_VALUES);
      NoiseLevels[band + env * noNoiseBands] = accu << 1;
    }
  }
}

/**************************************************************************/
/*!
  \brief     Does the noise floor level estiamtion.

  The noiseLevel samples are scaled by the factor 0.25

  \return    none

*/
/**************************************************************************/
static void qmfBasedNoiseFloorDetection(
    FIXP_DBL *noiseLevel,            /*!< Pointer to vector to
                                        store the noise levels
                                        in.*/
    FIXP_DBL **quotaMatrixOrig,      /*!< Matrix holding the quota
                                        values of the original. */
    SCHAR *indexVector,              /*!< Index vector to obtain the
                                        patched data. */
    INT startIndex,                  /*!< Start index. */
    INT stopIndex,                   /*!< Stop index. */
    INT startChannel,                /*!< Start channel of the current
                                        noise floor band.*/
    INT stopChannel,                 /*!< Stop channel of the current
                                        noise floor band. */
    FIXP_DBL ana_max_level,          /*!< Maximum level of the
                                        adaptive noise.*/
    FIXP_DBL noiseFloorOffset,       /*!< Noise floor offset. */
    INT missingHarmonicFlag,         /*!< Flag indicating if a
                                        strong tonal component
                                        is missing.*/
    FIXP_DBL weightFac,              /*!< Weightening factor for the
                                        difference between orig and sbr.
                                      */
    INVF_MODE diffThres,             /*!< Threshold value to control the
                                        inverse filtering decision.*/
    INVF_MODE inverseFilteringLevel) /*!< Inverse filtering
                                        level of the current
                                        band.*/
{
  INT scale, l, k;
  FIXP_DBL meanOrig = FL2FXCONST_DBL(0.0f), meanSbr = FL2FXCONST_DBL(0.0f),
           diff;
  FIXP_DBL invIndex = GetInvInt(stopIndex - startIndex);
  FIXP_DBL invChannel = GetInvInt(stopChannel - startChannel);
  FIXP_DBL accu;

  /*
  Calculate the mean value, over the current time segment, for the original, the
  HFR and the difference, over all channels in the current frequency range.
  */

  if (missingHarmonicFlag == 1) {
    for (l = startChannel; l < stopChannel; l++) {
      /* tonalityOrig */
      accu = FL2FXCONST_DBL(0.0f);
      for (k = startIndex; k < stopIndex; k++) {
        accu += fMultDiv2(quotaMatrixOrig[k][l], invIndex);
      }
      meanOrig = fixMax(meanOrig, (accu << 1));

      /* tonalitySbr */
      accu = FL2FXCONST_DBL(0.0f);
      for (k = startIndex; k < stopIndex; k++) {
        accu += fMultDiv2(quotaMatrixOrig[k][indexVector[l]], invIndex);
      }
      meanSbr = fixMax(meanSbr, (accu << 1));
    }
  } else {
    for (l = startChannel; l < stopChannel; l++) {
      /* tonalityOrig */
      accu = FL2FXCONST_DBL(0.0f);
      for (k = startIndex; k < stopIndex; k++) {
        accu += fMultDiv2(quotaMatrixOrig[k][l], invIndex);
      }
      meanOrig += fMult((accu << 1), invChannel);

      /* tonalitySbr */
      accu = FL2FXCONST_DBL(0.0f);
      for (k = startIndex; k < stopIndex; k++) {
        accu += fMultDiv2(quotaMatrixOrig[k][indexVector[l]], invIndex);
      }
      meanSbr += fMult((accu << 1), invChannel);
    }
  }

  /* Small fix to avoid noise during silent passages.*/
  if (meanOrig <= FL2FXCONST_DBL(0.000976562f * RELAXATION_FLOAT) &&
      meanSbr <= FL2FXCONST_DBL(0.000976562f * RELAXATION_FLOAT)) {
    meanOrig = FL2FXCONST_DBL(101.5936673f * RELAXATION_FLOAT);
    meanSbr = FL2FXCONST_DBL(101.5936673f * RELAXATION_FLOAT);
  }

  meanOrig = fixMax(meanOrig, RELAXATION);
  meanSbr = fixMax(meanSbr, RELAXATION);

  if (missingHarmonicFlag == 1 || inverseFilteringLevel == INVF_MID_LEVEL ||
      inverseFilteringLevel == INVF_LOW_LEVEL ||
      inverseFilteringLevel == INVF_OFF || inverseFilteringLevel <= diffThres) {
    diff = RELAXATION;
  } else {
    accu = fDivNorm(meanSbr, meanOrig, &scale);

    diff = fixMax(RELAXATION, fMult(RELAXATION_FRACT, fMult(weightFac, accu)) >>
                                  (RELAXATION_SHIFT - scale));
  }

  /*
   * noise Level is now a positive value, i.e.
   * the more harmonic the signal is the higher noise level,
   * this makes no sense so we change the sign.
   *********************************************************/
  accu = fDivNorm(diff, meanOrig, &scale);
  scale -= 2;

  if ((scale > 0) && (accu > ((FIXP_DBL)MAXVAL_DBL) >> scale)) {
    *noiseLevel = (FIXP_DBL)MAXVAL_DBL;
  } else {
    *noiseLevel = scaleValue(accu, scale);
  }

  /*
   * Add a noise floor offset to compensate for bias in the detector
   *****************************************************************/
  if (!missingHarmonicFlag) {
    *noiseLevel = fixMin(fMult(*noiseLevel, noiseFloorOffset),
                         (FIXP_DBL)MAXVAL_DBL >> NOISE_FLOOR_OFFSET_SCALING)
                  << NOISE_FLOOR_OFFSET_SCALING;
  }

  /*
   * check to see that we don't exceed the maximum allowed level
   **************************************************************/
  *noiseLevel =
      fixMin(*noiseLevel,
             ana_max_level); /* ana_max_level is scaled with factor 0.25 */
}

/**************************************************************************/
/*!
  \brief     Does the noise floor level estiamtion.
  The function calls the Noisefloor estimation function
  for the time segments decided based upon the transient
  information. The block is always divided into one or two segments.


  \return    none

*/
/**************************************************************************/
void FDKsbrEnc_sbrNoiseFloorEstimateQmf(
    HANDLE_SBR_NOISE_FLOOR_ESTIMATE
        h_sbrNoiseFloorEstimate, /*!< Handle to SBR_NOISE_FLOOR_ESTIMATE struct
                                  */
    const SBR_FRAME_INFO
        *frame_info, /*!< Time frequency grid of the current frame. */
    FIXP_DBL
        *noiseLevels, /*!< Pointer to vector to store the noise levels in.*/
    FIXP_DBL **quotaMatrixOrig, /*!< Matrix holding the quota values of the
                                   original. */
    SCHAR *indexVector,         /*!< Index vector to obtain the patched data. */
    INT missingHarmonicsFlag,   /*!< Flag indicating if a strong tonal component
                                   will be missing. */
    INT startIndex,             /*!< Start index. */
    UINT numberOfEstimatesPerFrame, /*!< The number of tonality estimates per
                                       frame. */
    int transientFrame, /*!< A flag indicating if a transient is present. */
    INVF_MODE *pInvFiltLevels, /*!< Pointer to the vector holding the inverse
                                  filtering levels. */
    UINT sbrSyntaxFlags)

{
  INT nNoiseEnvelopes, startPos[2], stopPos[2], env, band;

  INT noNoiseBands = h_sbrNoiseFloorEstimate->noNoiseBands;
  INT *freqBandTable = h_sbrNoiseFloorEstimate->freqBandTableQmf;

  nNoiseEnvelopes = frame_info->nNoiseEnvelopes;

  startPos[0] = startIndex;

  if (nNoiseEnvelopes == 1) {
    stopPos[0] = startIndex + min(numberOfEstimatesPerFrame, 2);
  } else {
    stopPos[0] = startIndex + 1;
    startPos[1] = startIndex + 1;
    stopPos[1] = startIndex + min(numberOfEstimatesPerFrame, 2);
  }

  /*
   * Estimate the noise floor.
   **************************************/
  for (env = 0; env < nNoiseEnvelopes; env++) {
    for (band = 0; band < noNoiseBands; band++) {
      FDK_ASSERT((band + env * noNoiseBands) < MAX_NUM_NOISE_VALUES);
      qmfBasedNoiseFloorDetection(
          &noiseLevels[band + env * noNoiseBands], quotaMatrixOrig, indexVector,
          startPos[env], stopPos[env], freqBandTable[band],
          freqBandTable[band + 1], h_sbrNoiseFloorEstimate->ana_max_level,
          h_sbrNoiseFloorEstimate->noiseFloorOffset[band], missingHarmonicsFlag,
          h_sbrNoiseFloorEstimate->weightFac,
          h_sbrNoiseFloorEstimate->diffThres, pInvFiltLevels[band]);
    }
  }

  /*
   * Smoothing of the values.
   **************************/
  smoothingOfNoiseLevels(noiseLevels, nNoiseEnvelopes,
                         h_sbrNoiseFloorEstimate->noNoiseBands,
                         h_sbrNoiseFloorEstimate->prevNoiseLevels,
                         h_sbrNoiseFloorEstimate->smoothFilter, transientFrame);

  /* quantisation*/
  for (env = 0; env < nNoiseEnvelopes; env++) {
    for (band = 0; band < noNoiseBands; band++) {
      FDK_ASSERT((band + env * noNoiseBands) < MAX_NUM_NOISE_VALUES);
      noiseLevels[band + env * noNoiseBands] =
          (FIXP_DBL)NOISE_FLOOR_OFFSET_64 -
          (FIXP_DBL)CalcLdData(noiseLevels[band + env * noNoiseBands] +
                               (FIXP_DBL)1) +
          QuantOffset;
    }
  }
}

/**************************************************************************/
/*!
  \brief


  \return    errorCode, noError if successful

*/
/**************************************************************************/
static INT downSampleLoRes(INT *v_result,                 /*!<    */
                           INT num_result,                /*!<    */
                           const UCHAR *freqBandTableRef, /*!<    */
                           INT num_Ref)                   /*!<    */
{
  INT step;
  INT i, j;
  INT org_length, result_length;
  INT v_index[MAX_FREQ_COEFFS / 2];

  /* init */
  org_length = num_Ref;
  result_length = num_result;

  v_index[0] = 0; /* Always use left border */
  i = 0;
  while (org_length > 0) /* Create downsample vector */
  {
    i++;
    step = org_length / result_length; /* floor; */
    org_length = org_length - step;
    result_length--;
    v_index[i] = v_index[i - 1] + step;
  }

  if (i != num_result) /* Should never happen */
    return (1);        /* error downsampling */

  for (j = 0; j <= i;
       j++) /* Use downsample vector to index LoResolution vector. */
  {
    v_result[j] = freqBandTableRef[v_index[j]];
  }

  return (0);
}

/**************************************************************************/
/*!
  \brief    Initialize an instance of the noise floor level estimation module.


  \return    errorCode, noError if successful

*/
/**************************************************************************/
INT FDKsbrEnc_InitSbrNoiseFloorEstimate(
    HANDLE_SBR_NOISE_FLOOR_ESTIMATE
        h_sbrNoiseFloorEstimate, /*!< Handle to SBR_NOISE_FLOOR_ESTIMATE struct
                                  */
    INT ana_max_level,           /*!< Maximum level of the adaptive noise. */
    const UCHAR *freqBandTable,  /*!< Frequency band table. */
    INT nSfb,                    /*!< Number of frequency bands. */
    INT noiseBands,              /*!< Number of noise bands per octave. */
    INT noiseFloorOffset,        /*!< Noise floor offset. */
    INT timeSlots,               /*!< Number of time slots in a frame. */
    UINT useSpeechConfig /*!< Flag: adapt tuning parameters according to speech
                          */
) {
  INT i, qexp, qtmp;
  FIXP_DBL tmp, exp;

  FDKmemclear(h_sbrNoiseFloorEstimate, sizeof(SBR_NOISE_FLOOR_ESTIMATE));

  h_sbrNoiseFloorEstimate->smoothFilter = smoothFilter;
  if (useSpeechConfig) {
    h_sbrNoiseFloorEstimate->weightFac = (FIXP_DBL)MAXVAL_DBL;
    h_sbrNoiseFloorEstimate->diffThres = INVF_LOW_LEVEL;
  } else {
    h_sbrNoiseFloorEstimate->weightFac = FL2FXCONST_DBL(0.25f);
    h_sbrNoiseFloorEstimate->diffThres = INVF_MID_LEVEL;
  }

  h_sbrNoiseFloorEstimate->timeSlots = timeSlots;
  h_sbrNoiseFloorEstimate->noiseBands = noiseBands;

  /* h_sbrNoiseFloorEstimate->ana_max_level is scaled by 0.25  */
  switch (ana_max_level) {
    case 6:
      h_sbrNoiseFloorEstimate->ana_max_level = (FIXP_DBL)MAXVAL_DBL;
      break;
    case 3:
      h_sbrNoiseFloorEstimate->ana_max_level = FL2FXCONST_DBL(0.5);
      break;
    case -3:
      h_sbrNoiseFloorEstimate->ana_max_level = FL2FXCONST_DBL(0.125);
      break;
    default:
      /* Should not enter here */
      h_sbrNoiseFloorEstimate->ana_max_level = (FIXP_DBL)MAXVAL_DBL;
      break;
  }

  /*
    calculate number of noise bands and allocate
  */
  if (FDKsbrEnc_resetSbrNoiseFloorEstimate(h_sbrNoiseFloorEstimate,
                                           freqBandTable, nSfb))
    return (1);

  if (noiseFloorOffset == 0) {
    tmp = ((FIXP_DBL)MAXVAL_DBL) >> NOISE_FLOOR_OFFSET_SCALING;
  } else {
    /* noiseFloorOffset has to be smaller than 12, because
       the result of the calculation below must be smaller than 1:
       (2^(noiseFloorOffset/3))*2^4<1                                        */
    FDK_ASSERT(noiseFloorOffset < 12);

    /* Assumes the noise floor offset in tuning table are in q31    */
    /* Change the qformat here when non-zero values would be filled */
    exp = fDivNorm((FIXP_DBL)noiseFloorOffset, 3, &qexp);
    tmp = fPow(2, DFRACT_BITS - 1, exp, qexp, &qtmp);
    tmp = scaleValue(tmp, qtmp - NOISE_FLOOR_OFFSET_SCALING);
  }

  for (i = 0; i < h_sbrNoiseFloorEstimate->noNoiseBands; i++) {
    h_sbrNoiseFloorEstimate->noiseFloorOffset[i] = tmp;
  }

  return (0);
}

/**************************************************************************/
/*!
  \brief     Resets the current instance of the noise floor estiamtion
          module.


  \return    errorCode, noError if successful

*/
/**************************************************************************/
INT FDKsbrEnc_resetSbrNoiseFloorEstimate(
    HANDLE_SBR_NOISE_FLOOR_ESTIMATE
        h_sbrNoiseFloorEstimate, /*!< Handle to SBR_NOISE_FLOOR_ESTIMATE struct
                                  */
    const UCHAR *freqBandTable,  /*!< Frequency band table. */
    INT nSfb /*!< Number of bands in the frequency band table. */
) {
  INT k2, kx;

  /*
   * Calculate number of noise bands
   ***********************************/
  k2 = freqBandTable[nSfb];
  kx = freqBandTable[0];
  if (h_sbrNoiseFloorEstimate->noiseBands == 0) {
    h_sbrNoiseFloorEstimate->noNoiseBands = 1;
  } else {
    /*
     * Calculate number of noise bands 1,2 or 3 bands/octave
     ********************************************************/
    FIXP_DBL tmp, ratio, lg2;
    INT ratio_e, qlg2, nNoiseBands;

    ratio = fDivNorm(k2, kx, &ratio_e);
    lg2 = fLog2(ratio, ratio_e, &qlg2);
    tmp = fMult((FIXP_DBL)(h_sbrNoiseFloorEstimate->noiseBands << 24), lg2);
    tmp = scaleValue(tmp, qlg2 - 23);

    nNoiseBands = (INT)((tmp + (FIXP_DBL)1) >> 1);

    if (nNoiseBands > MAX_NUM_NOISE_COEFFS) {
      nNoiseBands = MAX_NUM_NOISE_COEFFS;
    }

    if (nNoiseBands == 0) {
      nNoiseBands = 1;
    }

    h_sbrNoiseFloorEstimate->noNoiseBands = nNoiseBands;
  }

  return (downSampleLoRes(h_sbrNoiseFloorEstimate->freqBandTableQmf,
                          h_sbrNoiseFloorEstimate->noNoiseBands, freqBandTable,
                          nSfb));
}

/**************************************************************************/
/*!
  \brief     Deletes the current instancce of the noise floor level
  estimation module.


  \return    none

*/
/**************************************************************************/
void FDKsbrEnc_deleteSbrNoiseFloorEstimate(
    HANDLE_SBR_NOISE_FLOOR_ESTIMATE
        h_sbrNoiseFloorEstimate) /*!< Handle to SBR_NOISE_FLOOR_ESTIMATE struct
                                  */
{
  if (h_sbrNoiseFloorEstimate) {
    /*
      nothing to do
    */
  }
}