path: root/libSBRenc/src/resampler.cpp

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    Confidential Information of Fraunhofer and subject to and covered by the

    Fraunhofer IIS Software Evaluation Agreement
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    Evaluation Agreement. Any other and/or further use requires a separate agreement.


   This software and/or program is protected by copyright law and international
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   will be prosecuted to the maximum extent possible under law.

 $Id$

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

/*!
  \file
  \brief  FDK resampler tool box:$Revision: 11752 $
  \author M. Werner
*/

#include "resampler.h"

#include "genericStds.h"


/**************************************************************************/
/*                   BIQUAD Filter Specifications                         */
/**************************************************************************/

#define B1 0
#define B2 1
#define A1 2
#define A2 3

#define BQC(x) FL2FXCONST_SGL(x/2)


struct FILTER_PARAM {
  const FIXP_SGL *coeffa;    /*! SOS matrix One row/section. Scaled using BQC(). Order of coefficients: B1,B2,A1,A2. B0=A0=1.0 */
  FIXP_DBL g;                /*! overall gain */
  int Wc;                    /*! normalized passband bandwidth at input samplerate * 1000 */
  int noCoeffs;              /*! number of filter coeffs */
  int delay;                 /*! delay in samples at input samplerate */
};

#define BIQUAD_COEFSTEP 4

/**
 *\brief Low Pass
 Wc = 0,5, order 30, Stop Band -96dB. Wc criteria is "almost 0dB passband", not the usual -3db gain point.
 [b,a]=cheby2(30,96,0.505)
 [sos,g]=tf2sos(b,a)
 bandwidth 0.48
 */
static const FIXP_SGL sos48[] = {
 BQC(1.98941075681938),   BQC(0.999999996890811), BQC(0.863264527201963),     BQC( 0.189553799960663),
 BQC(1.90733804822445),   BQC(1.00000001736189),  BQC(0.836321575841691),     BQC( 0.203505809266564),
 BQC(1.75616665495325),   BQC(0.999999946079721), BQC(0.784699225121588),     BQC( 0.230471265506986),
 BQC(1.55727745512726),   BQC(1.00000011737815),  BQC(0.712515423588351),     BQC( 0.268752723900498),
 BQC(1.33407591943643),   BQC(0.999999795953228), BQC(0.625059117330989),     BQC( 0.316194685288965),
 BQC(1.10689898412458),   BQC(1.00000035057114),  BQC(0.52803514366398),      BQC( 0.370517843224669),
 BQC(0.89060371078454),   BQC(0.999999343962822), BQC(0.426920462165257),     BQC( 0.429608200207746),
 BQC(0.694438261209433),  BQC( 1.0000008629792),  BQC(0.326530699561716),     BQC( 0.491714450654174),
 BQC(0.523237800935322),  BQC(1.00000101349782),  BQC(0.230829556274851),     BQC( 0.555559034843281),
 BQC(0.378631165929563),  BQC(0.99998986482665),  BQC(0.142906422036095),     BQC( 0.620338874442411),
 BQC(0.260786911308437),  BQC(1.00003261460178),  BQC(0.0651008576256505),    BQC( 0.685759923926262),
 BQC(0.168409429188098),  BQC(0.999933049695828), BQC(-0.000790067789975562), BQC( 0.751905896602325),
 BQC(0.100724533818628),  BQC(1.00009472669872),  BQC(-0.0533772830257041),   BQC( 0.81930744384525),
 BQC(0.0561434357867363), BQC(0.999911636304276), BQC(-0.0913550299236405),   BQC( 0.88883625875915),
 BQC(0.0341680678662057), BQC(1.00003667508676),  BQC(-0.113405185536697),    BQC( 0.961756638268446)
};

#ifdef RS_BIQUAD_SCATTERGAIN
static const FIXP_DBL g48 = FL2FXCONST_DBL(0.67436532061161992682404480717671 - 0.001);
#else
static const FIXP_DBL g48 = FL2FXCONST_DBL(0.002712866530047) - (FIXP_DBL)0x8000;
#endif

static const struct FILTER_PARAM param_set48 = {
  sos48,
  g48,
  480,
  15,
  4 /* LF 2 */
};

/**
 *\brief Low Pass
 Wc = 0,5, order 24, Stop Band -96dB. Wc criteria is "almost 0dB passband", not the usual -3db gain point.
 [b,a]=cheby2(24,96,0.5)
 [sos,g]=tf2sos(b,a)
 bandwidth 0.45
 */
static const FIXP_SGL sos45[] = {
  BQC(1.982962601444),     BQC(1.00000000007504),  BQC(0.646113303737836),   BQC( 0.10851149979981),
  BQC(1.85334094281111),   BQC(0.999999999677192), BQC(0.612073220102006),   BQC( 0.130022141698044),
  BQC(1.62541051415425),   BQC(1.00000000080398),  BQC(0.547879702855959),   BQC( 0.171165825133192),
  BQC(1.34554656923247),   BQC(0.9999999980169),   BQC(0.460373914508491),   BQC( 0.228677463376354),
  BQC(1.05656568503116),   BQC(1.00000000569363),  BQC(0.357891894038287),   BQC( 0.298676843912185),
  BQC(0.787967587877312),  BQC(0.999999984415017), BQC(0.248826893211877),   BQC( 0.377441803512978),
  BQC(0.555480971120497),  BQC(1.00000003583307),  BQC(0.140614263345315),   BQC( 0.461979302213679),
  BQC(0.364986207070964),  BQC(0.999999932084303), BQC(0.0392669446074516),  BQC( 0.55033451180825),
  BQC(0.216827267631558),  BQC(1.00000010534682),  BQC(-0.0506232228865103), BQC( 0.641691581560946),
  BQC(0.108951672277119),  BQC(0.999999871167516), BQC(-0.125584840183225),  BQC( 0.736367748771803),
  BQC(0.0387988607229035), BQC(1.00000011205574),  BQC(-0.182814849097974),  BQC( 0.835802108714964),
  BQC(0.0042866175809225), BQC(0.999999954830813), BQC(-0.21965740617151),   BQC( 0.942623047782363)
};

#ifdef RS_BIQUAD_SCATTERGAIN
static const FIXP_DBL g45 = FL2FXCONST_DBL(0.60547428891341319051142629706723 - 0.001);
#else
static const FIXP_DBL g45 = FL2FXCONST_DBL(0.00242743980909524) - (FIXP_DBL)0x8000;
#endif

static const struct FILTER_PARAM param_set45 = {
  sos45,
  g45,
  450,
  12,
  4 /* LF 2 */
};

/*
 Created by Octave 2.1.73, Mon Oct 13 17:31:32 2008 CEST
 Wc = 0,5, order 16, Stop Band -96dB damping.
 [b,a]=cheby2(16,96,0.5)
 [sos,g]=tf2sos(b,a)
 bandwidth = 0.41
 */

static const FIXP_SGL sos41[] =
{
  BQC(1.96193625292),       BQC(0.999999999999964), BQC(0.169266178786789),   BQC(0.0128823300475907),
  BQC(1.68913437662092),    BQC(1.00000000000053),  BQC(0.124751503206552),   BQC(0.0537472273950989),
  BQC(1.27274692366017),    BQC(0.999999999995674), BQC(0.0433108625178357),  BQC(0.131015753236317),
  BQC(0.85214175088395),    BQC(1.00000000001813),  BQC(-0.0625658152550408), BQC(0.237763778993806),
  BQC(0.503841579939009),   BQC(0.999999999953223), BQC(-0.179176128722865),  BQC(0.367475236424474),
  BQC(0.249990711986162),   BQC(1.00000000007952),  BQC(-0.294425165824676),  BQC(0.516594857170212),
  BQC(0.087971668680286),   BQC(0.999999999915528), BQC(-0.398956566777928),  BQC(0.686417767801123),
  BQC(0.00965373325350294), BQC(1.00000000003744),  BQC(-0.48579173764817),   BQC(0.884931534239068)
};

#ifdef RS_BIQUAD_SCATTERGAIN
static const FIXP_DBL g41 = FL2FXCONST_DBL(0.44578514476476679750811222123569);
#else
static const FIXP_DBL g41 = FL2FXCONST_DBL(0.00155956951169248);
#endif

static const struct FILTER_PARAM param_set41 = {
  sos41,
  g41,
  410,
  8,
  5 /* LF 3 */
};

/*
 # Created by Octave 2.1.73, Mon Oct 13 17:55:33 2008 CEST
 Wc = 0,5, order 12, Stop Band -96dB damping.
 [b,a]=cheby2(12,96,0.5);
 [sos,g]=tf2sos(b,a)
*/
static const FIXP_SGL sos35[] =
{
  BQC(1.93299325235762),   BQC(0.999999999999985), BQC(-0.140733187246596), BQC(0.0124139497836062),
  BQC(1.4890416764109),    BQC(1.00000000000011),  BQC(-0.198215402588504), BQC(0.0746730616584138),
  BQC(0.918450161309795),  BQC(0.999999999999619), BQC(-0.30133912791941),  BQC(0.192276468839529),
  BQC(0.454877024246818),  BQC(1.00000000000086),  BQC(-0.432337328809815), BQC(0.356852933642815),
  BQC(0.158017147118507),  BQC(0.999999999998876), BQC(-0.574817494249777), BQC(0.566380436970833),
  BQC(0.0171834649478749), BQC(1.00000000000055),  BQC(-0.718581178041165), BQC(0.83367484487889)
};

#ifdef RS_BIQUAD_SCATTERGAIN
static const FIXP_DBL g35 = FL2FXCONST_DBL(0.34290853574973898694521267606792);
#else
static const FIXP_DBL g35 = FL2FXCONST_DBL(0.00162580994125131);
#endif

static const struct FILTER_PARAM param_set35 = {
  sos35,
  g35,
  350,
  6,
  4
};

/*
 # Created by Octave 2.1.73, Mon Oct 13 18:15:38 2008 CEST
 Wc = 0,5, order 8, Stop Band -96dB damping.
 [b,a]=cheby2(8,96,0.5);
 [sos,g]=tf2sos(b,a)
*/
static const FIXP_SGL sos25[] =
{
  BQC(1.85334094301225),   BQC(1.0),               BQC(-0.702127214212663), BQC(0.132452403998767),
  BQC(1.056565682167),     BQC(0.999999999999997), BQC(-0.789503667880785), BQC(0.236328693569128),
  BQC(0.364986307455489),  BQC(0.999999999999996), BQC(-0.955191189843375), BQC(0.442966457936379),
  BQC(0.0387985751642125), BQC(1.0),               BQC(-1.19817786088084),  BQC(0.770493895456328)
};

#ifdef RS_BIQUAD_SCATTERGAIN
static const FIXP_DBL g25 = FL2FXCONST_DBL(0.17533917408936346960080259950471);
#else
static const FIXP_DBL g25 = FL2FXCONST_DBL(0.000945182835294559);
#endif

static const struct FILTER_PARAM param_set25 = {
  sos25,
  g25,
  250,
  4,
  5
};

/* Must be sorted in descending order */
static const struct FILTER_PARAM *const filter_paramSet[] = {
  &param_set48,
  &param_set45,
  &param_set41,
  &param_set35,
  &param_set25
};


/**************************************************************************/
/*                         Resampler Functions                            */
/**************************************************************************/


/*!
  \brief   Reset downsampler instance and clear delay lines

  \return  success of operation
*/

INT FDKaacEnc_InitDownsampler(DOWNSAMPLER *DownSampler, /*!< pointer to downsampler instance */
                              int Wc,                   /*!< normalized cutoff freq * 1000*  */
                              int ratio)                /*!< downsampler ratio (only 2 supported at the momment) */

{
  UINT i;
  const struct FILTER_PARAM *currentSet=NULL;

  FDK_ASSERT(ratio == 2);
  FDKmemclear(DownSampler->downFilter.states, sizeof(DownSampler->downFilter.states));
  DownSampler->downFilter.ptr   =   0;

  /*
    find applicable parameter set
  */
  currentSet = filter_paramSet[0];
  for(i=1;i<sizeof(filter_paramSet)/sizeof(struct FILTER_PARAM *);i++){
    if (filter_paramSet[i]->Wc <= Wc) {
      break;
    }
    currentSet = filter_paramSet[i];
  }

  DownSampler->downFilter.coeffa = currentSet->coeffa;


  DownSampler->downFilter.gain = currentSet->g;
  FDK_ASSERT(currentSet->noCoeffs <= MAXNR_SECTIONS*2);

  DownSampler->downFilter.noCoeffs = currentSet->noCoeffs;
  DownSampler->delay = currentSet->delay;
  DownSampler->downFilter.Wc = currentSet->Wc;

  DownSampler->ratio =   ratio;
  DownSampler->pending = ratio-1;
  return(1);
}


/*!
  \brief   faster simple folding operation
           Filter:
           H(z) = A(z)/B(z)
           with
           A(z) = a[0]*z^0 + a[1]*z^1 + a[2]*z^2 ... a[n]*z^n

  \return  filtered value
*/

static inline INT_PCM AdvanceFilter(LP_FILTER *downFilter,  /*!< pointer to iir filter instance */
                                     INT_PCM  *pInput,          /*!< input of filter                */
                                     int downRatio,
                                     int inStride)
{
  INT_PCM output;
  int i, n;


#ifdef RS_BIQUAD_SCATTERGAIN
#define BIQUAD_SCALE 3
#else
#define BIQUAD_SCALE 12
#endif

  FIXP_DBL y = FL2FXCONST_DBL(0.0f);
  FIXP_DBL input;

  for (n=0; n<downRatio; n++)
  {
    FIXP_BQS (*states)[2] = downFilter->states;
    const FIXP_SGL *coeff = downFilter->coeffa;
    int s1,s2;

    s1 = downFilter->ptr;
    s2 = s1 ^ 1;

#if (SAMPLE_BITS == 16)
    input =  ((FIXP_DBL)pInput[n*inStride]) << (DFRACT_BITS-SAMPLE_BITS-BIQUAD_SCALE);
#elif (SAMPLE_BITS == 32)
    input =  pInput[n*inStride] >> BIQUAD_SCALE;
#else
#error NOT IMPLEMENTED
#endif

#ifndef RS_BIQUAD_SCATTERGAIN /* Merged Direct form I */

    FIXP_BQS state1, state2, state1b, state2b;

    state1 = states[0][s1];
    state2 = states[0][s2];

    /* Loop over sections */
    for (i=0; i<downFilter->noCoeffs; i++)
    {
      FIXP_DBL state0;

      /* Load merged states (from next section) */
      state1b = states[i+1][s1];
      state2b = states[i+1][s2];

      state0 = input  + fMult(state1, coeff[B1]) + fMult(state2, coeff[B2]);
      y      = state0 - fMult(state1b, coeff[A1]) - fMult(state2b, coeff[A2]);

      /* Store new feed forward merge state */
      states[i+1][s2] = y<<1;
      /* Store new feed backward state */
      states[i][s2] = input<<1;

      /* Feedback output to next section. */
      input = y;

      /* Transfer merged states */
      state1 = state1b;
      state2 = state2b;

      /* Step to next coef set */
      coeff += BIQUAD_COEFSTEP;
    }
    downFilter->ptr ^= 1;
  }
  /* Apply global gain */
  y = fMult(y, downFilter->gain);

#else /* Direct form II */

    /* Loop over sections */
    for (i=0; i<downFilter->noCoeffs; i++)
    {
      FIXP_BQS state1, state2;
      FIXP_DBL state0;

      /* Load states */
      state1 = states[i][s1];
      state2 = states[i][s2];

      state0 = input  - fMult(state1, coeff[A1]) - fMult(state2, coeff[A2]);
      y = state0      + fMult(state1, coeff[B1]) + fMult(state2, coeff[B2]);
      /* Apply scattered gain */
      y = fMult(y, downFilter->gain);

      /* Store new state in normalized form */
#ifdef RS_BIQUAD_STATES16
      /* Do not saturate any state value ! The result would be unacceptable. Rounding makes SNR around 10dB better. */
      states[i][s2] = (FIXP_BQS)(LONG)((state0 + (FIXP_DBL)(1<<(DFRACT_BITS-FRACT_BITS-2))) >> (DFRACT_BITS-FRACT_BITS-1));
#else
      states[i][s2] = state0<<1;
#endif

      /* Feedback output to next section. */
      input=y;

      /* Step to next coef set */
      coeff += BIQUAD_COEFSTEP;
    }
    downFilter->ptr ^= 1;
  }

#endif

  /* Apply final gain/scaling to output */
#if (SAMPLE_BITS == 16)
  output = (INT_PCM) SATURATE_RIGHT_SHIFT(y+(FIXP_DBL)(1<<(DFRACT_BITS-SAMPLE_BITS-BIQUAD_SCALE-1)), DFRACT_BITS-SAMPLE_BITS-BIQUAD_SCALE, SAMPLE_BITS);
  //output = (INT_PCM) SATURATE_RIGHT_SHIFT(y, DFRACT_BITS-SAMPLE_BITS-BIQUAD_SCALE, SAMPLE_BITS);
#else
  output = SATURATE_LEFT_SHIFT(y, BIQUAD_SCALE, SAMPLE_BITS);
#endif


  return output;
}




/*!
  \brief   FDKaacEnc_Downsample numInSamples of type INT_PCM
           Returns number of output samples in numOutSamples

  \return  success of operation
*/

INT FDKaacEnc_Downsample(DOWNSAMPLER *DownSampler,  /*!< pointer to downsampler instance */
                         INT_PCM *inSamples,        /*!< pointer to input samples */
                         INT numInSamples,          /*!< number  of input samples  */
                         INT inStride,              /*!< increment of input samples */
                         INT_PCM *outSamples,       /*!< pointer to output samples */
                         INT *numOutSamples,        /*!< pointer tp number of output samples */
                         INT outStride              /*!< increment of output samples */
                         )
{
    INT i;
    *numOutSamples=0;

    for(i=0; i<numInSamples; i+=DownSampler->ratio)
    {
      *outSamples = AdvanceFilter(&(DownSampler->downFilter), &inSamples[i*inStride], DownSampler->ratio, inStride);
      outSamples += outStride;
    }
    *numOutSamples = numInSamples/DownSampler->ratio;

    return 0;
}