libAACenc/src/noisedet.cpp

   1
   2 /* -----------------------------------------------------------------------------------------------------------
   3 Software License for The Fraunhofer FDK AAC Codec Library for Android
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   5 © Copyright  1995 - 2013 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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   8  1.    INTRODUCTION
   9 The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements
  10 the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio.
  11 This FDK AAC Codec software is intended to be used on a wide variety of Android devices.
  12
  13 AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual
  14 audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by
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  16 of the MPEG specifications.
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  21 the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license
  22 these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec
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  64 This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors
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  73 5.    CONTACT INFORMATION
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  75 Fraunhofer Institute for Integrated Circuits IIS
  76 Attention: Audio and Multimedia Departments - FDK AAC LL
  77 Am Wolfsmantel 33
  78 91058 Erlangen, Germany
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  80 www.iis.fraunhofer.de/amm
  81 amm-info@iis.fraunhofer.de
  82 ----------------------------------------------------------------------------------------------------------- */
  83
  84 /******************************** MPEG Audio Encoder **************************
  85
  86    Initial author:       M. Lohwasser
  87    contents/description: noisedet.c
  88                          Routines for Noise Detection
  89
  90 ******************************************************************************/
  91
  92 #include "noisedet.h"
  93
  94 #include "aacenc_pns.h"
  95 #include "pnsparam.h"
  96
  97
  98 /*****************************************************************************
  99
 100     functionname: FDKaacEnc_fuzzyIsSmaller
 101     description:  Fuzzy value calculation for "testVal is smaller than refVal"
 102     returns:      fuzzy value
 103     input:        test and ref Value,
 104                   low and high Lim
 105     output:       return fuzzy value
 106
 107 *****************************************************************************/
 108 static FIXP_SGL FDKaacEnc_fuzzyIsSmaller( FIXP_DBL testVal,
 109                                 FIXP_DBL refVal,
 110                                 FIXP_DBL loLim,
 111                                 FIXP_DBL hiLim )
 112 {
 113   if (refVal <= FL2FXCONST_DBL(0.0))
 114         return( FL2FXCONST_SGL(0.0f) );
 115   else if (testVal >= fMult((hiLim>>1)+(loLim>>1), refVal))
 116         return( FL2FXCONST_SGL(0.0f) );
 117   else  return( (FIXP_SGL)MAXVAL_SGL );
 118 }
 119
 120
 121
 122 /*****************************************************************************
 123
 124     functionname: FDKaacEnc_noiseDetect
 125     description:  detect tonal sfb's; two tests
 126                   Powerdistribution:
 127                     sfb splittet in four regions,
 128                     compare the energy in all sections
 129                   PsychTonality:
 130                     compare tonality from chaosmeasure with reftonality
 131     returns:
 132     input:        spectrum of one large mdct
 133                   number of sfb's
 134                   pointer to offset of sfb's
 135                   pointer to noiseFuzzyMeasure (modified)
 136                   noiseparams struct
 137                   pointer to sfb energies
 138                   pointer to tonality calculated in chaosmeasure
 139     output:       noiseFuzzy Measure
 140
 141 *****************************************************************************/
 142
 143 void FDKaacEnc_noiseDetect(FIXP_DBL    *RESTRICT mdctSpectrum,
 144                  INT         *RESTRICT sfbMaxScaleSpec,
 145                  INT          sfbActive,
 146                  const INT   *RESTRICT sfbOffset,
 147                  FIXP_SGL    *RESTRICT noiseFuzzyMeasure,
 148                  NOISEPARAMS *np,
 149                  FIXP_SGL    *RESTRICT sfbtonality )
 150
 151 {
 152   int    i, k, sfb, sfbWidth;
 153   FIXP_SGL fuzzy, fuzzyTotal;
 154   FIXP_DBL refVal, testVal;
 155
 156   /***** Start detection phase *****/
 157   /* Start noise detection for each band based on a number of checks */
 158   for (sfb=0; sfb<sfbActive; sfb++) {
 159
 160     fuzzyTotal = (FIXP_SGL)MAXVAL_SGL;
 161     sfbWidth = sfbOffset[sfb+1] - sfbOffset[sfb];
 162
 163     /* Reset output for lower bands or too small bands */
 164     if (sfb < np->startSfb  ||  sfbWidth < np->minSfbWidth) {
 165       noiseFuzzyMeasure[sfb] = FL2FXCONST_SGL(0.0f);
 166       continue;
 167     }
 168
 169     if ( (np->detectionAlgorithmFlags & USE_POWER_DISTRIBUTION) && (fuzzyTotal > FL2FXCONST_SGL(0.5f)) ) {
 170       FIXP_DBL fhelp1, fhelp2, fhelp3, fhelp4, maxVal, minVal;
 171       INT leadingBits = fixMax(0,(sfbMaxScaleSpec[sfb] - 3));         /* max sfbWidth = 96/4 ; 2^5=32 => 5/2 = 3 (spc*spc) */
 172
 173       /*  check power distribution in four regions */
 174       fhelp1 = fhelp2 = fhelp3 = fhelp4 = FL2FXCONST_DBL(0.0f);
 175       k = sfbWidth >>2;  /* Width of a quarter band */
 176
 177       for (i=sfbOffset[sfb]; i<sfbOffset[sfb]+k; i++) {
 178         fhelp1 = fPow2AddDiv2(fhelp1, mdctSpectrum[i]<<leadingBits);
 179         fhelp2 = fPow2AddDiv2(fhelp2, mdctSpectrum[i+k]<<leadingBits);
 180         fhelp3 = fPow2AddDiv2(fhelp3, mdctSpectrum[i+2*k]<<leadingBits);
 181         fhelp4 = fPow2AddDiv2(fhelp4, mdctSpectrum[i+3*k]<<leadingBits);
 182       }
 183
 184       /* get max into fhelp: */
 185       maxVal = fixMax(fhelp1, fhelp2);
 186       maxVal = fixMax(maxVal, fhelp3);
 187       maxVal = fixMax(maxVal, fhelp4);
 188
 189       /* get min into fhelp1: */
 190       minVal = fixMin(fhelp1, fhelp2);
 191       minVal = fixMin(minVal, fhelp3);
 192       minVal = fixMin(minVal, fhelp4);
 193
 194       /* Normalize min and max Val */
 195       leadingBits = CountLeadingBits(maxVal);
 196       testVal = maxVal << leadingBits;
 197       refVal  = minVal << leadingBits;
 198
 199       /* calculate fuzzy value for power distribution */
 200       testVal = fMultDiv2(testVal, np->powDistPSDcurve[sfb]);
 201
 202       fuzzy = FDKaacEnc_fuzzyIsSmaller(testVal,           /* 1/2 * maxValue * PSDcurve */
 203                              refVal,            /* 1   * minValue            */
 204                              FL2FXCONST_DBL(0.495),  /* 1/2 * loLim  (0.99f/2)    */
 205                              FL2FXCONST_DBL(0.505)); /* 1/2 * hiLim  (1.01f/2)    */
 206
 207       fuzzyTotal = fixMin(fuzzyTotal, fuzzy);
 208     }
 209
 210     if ( (np->detectionAlgorithmFlags & USE_PSYCH_TONALITY) && (fuzzyTotal > FL2FXCONST_SGL(0.5f)) ) {
 211       /* Detection with tonality-value of psych. acoustic (here: 1 is tonal!)*/
 212
 213       testVal = FX_SGL2FX_DBL(sfbtonality[sfb])>>1;          /* 1/2 * sfbTonality         */
 214       refVal  = np->refTonality;
 215
 216       fuzzy   = FDKaacEnc_fuzzyIsSmaller(testVal,
 217                                refVal,
 218                                FL2FXCONST_DBL(0.45f),    /* 1/2 * loLim  (0.9f/2)     */
 219                                FL2FXCONST_DBL(0.55f));   /* 1/2 * hiLim  (1.1f/2)     */
 220
 221       fuzzyTotal = fixMin(fuzzyTotal, fuzzy);
 222     }
 223
 224
 225     /* Output of final result */
 226     noiseFuzzyMeasure[sfb] = fuzzyTotal;
 227   }
 228 }