libAACenc/src/band_nrg.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
  15 independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part
  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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  73 5.    CONTACT INFORMATION
  74
  75 Fraunhofer Institute for Integrated Circuits IIS
  76 Attention: Audio and Multimedia Departments - FDK AAC LL
  77 Am Wolfsmantel 33
  78 91058 Erlangen, Germany
  79
  80 www.iis.fraunhofer.de/amm
  81 amm-info@iis.fraunhofer.de
  82 ----------------------------------------------------------------------------------------------------------- */
  83
  84 /*****************************  MPEG-4 AAC Encoder  **************************
  85
  86    Initial author:       M. Werner
  87    contents/description: Band/Line energy calculations
  88
  89 ******************************************************************************/
  90
  91 #include "band_nrg.h"
  92
  93
  94 /*****************************************************************************
  95   functionname: FDKaacEnc_CalcSfbMaxScaleSpec
  96   description:
  97   input:
  98   output:
  99 *****************************************************************************/
 100 void
 101 FDKaacEnc_CalcSfbMaxScaleSpec(const FIXP_DBL *RESTRICT mdctSpectrum,
 102                               const INT      *RESTRICT bandOffset,
 103                               INT            *RESTRICT sfbMaxScaleSpec,
 104                               const INT       numBands)
 105 {
 106   INT i,j;
 107   FIXP_DBL maxSpc, tmp;
 108
 109   for(i=0; i<numBands; i++) {
 110     maxSpc = (FIXP_DBL)0;
 111     for (j=bandOffset[i]; j<bandOffset[i+1]; j++) {
 112       tmp = fixp_abs(mdctSpectrum[j]);
 113       maxSpc = fixMax(maxSpc, tmp);
 114     }
 115     sfbMaxScaleSpec[i] = (maxSpc==(FIXP_DBL)0) ? (DFRACT_BITS-2) : CntLeadingZeros(maxSpc)-1;
 116     /* CountLeadingBits() is not necessary here since test value is always > 0 */
 117   }
 118 }
 119
 120 /*****************************************************************************
 121   functionname: FDKaacEnc_CheckBandEnergyOptim
 122   description:
 123   input:
 124   output:
 125 *****************************************************************************/
 126 FIXP_DBL
 127 FDKaacEnc_CheckBandEnergyOptim(const FIXP_DBL *RESTRICT mdctSpectrum,
 128                                INT            *RESTRICT sfbMaxScaleSpec,
 129                                const INT      *RESTRICT bandOffset,
 130                                const INT       numBands,
 131                                FIXP_DBL       *RESTRICT bandEnergy,
 132                                FIXP_DBL       *RESTRICT bandEnergyLdData,
 133                                INT             minSpecShift)
 134 {
 135   INT i, j, scale, nr = 0;
 136   FIXP_DBL maxNrgLd = FL2FXCONST_DBL(-1.0f);
 137   FIXP_DBL maxNrg = 0;
 138   FIXP_DBL spec;
 139
 140   for(i=0; i<numBands; i++) {
 141     scale = fixMax(0, sfbMaxScaleSpec[i]-4);
 142     FIXP_DBL tmp = 0;
 143     for (j=bandOffset[i]; j<bandOffset[i+1]; j++){
 144        spec = mdctSpectrum[j]<<scale;
 145        tmp = fPow2AddDiv2(tmp, spec);
 146     }
 147     bandEnergy[i] = tmp<<1;
 148
 149     /* calculate ld of bandNrg, subtract scaling */
 150     bandEnergyLdData[i] = CalcLdData(bandEnergy[i]);
 151     if (bandEnergyLdData[i] != FL2FXCONST_DBL(-1.0f)) {
 152       bandEnergyLdData[i] -= scale*FL2FXCONST_DBL(2.0/64);
 153     }
 154     /* find index of maxNrg */
 155     if (bandEnergyLdData[i] > maxNrgLd) {
 156         maxNrgLd = bandEnergyLdData[i];
 157         nr = i;
 158     }
 159   }
 160
 161   /* return unscaled maxNrg*/
 162   scale = fixMax(0,sfbMaxScaleSpec[nr]-4);
 163   scale = fixMax(2*(minSpecShift-scale),-(DFRACT_BITS-1));
 164
 165   maxNrg = scaleValue(bandEnergy[nr], scale);
 166
 167   return maxNrg;
 168 }
 169
 170 /*****************************************************************************
 171   functionname: FDKaacEnc_CalcBandEnergyOptimLong
 172   description:
 173   input:
 174   output:
 175 *****************************************************************************/
 176 INT
 177 FDKaacEnc_CalcBandEnergyOptimLong(const FIXP_DBL *RESTRICT mdctSpectrum,
 178                                   INT            *RESTRICT sfbMaxScaleSpec,
 179                                   const INT      *RESTRICT bandOffset,
 180                                   const INT       numBands,
 181                                   FIXP_DBL       *RESTRICT bandEnergy,
 182                                   FIXP_DBL       *RESTRICT bandEnergyLdData)
 183 {
 184   INT i, j, shiftBits = 0;
 185   FIXP_DBL maxNrgLd = FL2FXCONST_DBL(0.0f);
 186
 187   FIXP_DBL spec;
 188
 189   for(i=0; i<numBands; i++) {
 190      INT leadingBits = sfbMaxScaleSpec[i]-4;            /* max sfbWidth = 96 ; 2^7=128 => 7/2 = 4 (spc*spc) */
 191      FIXP_DBL tmp = FL2FXCONST_DBL(0.0);
 192      /* don't use scaleValue() here, it increases workload quite sufficiently... */
 193      if (leadingBits>=0) {
 194         for (j=bandOffset[i];j<bandOffset[i+1];j++) {
 195            spec = mdctSpectrum[j]<<leadingBits;
 196            tmp = fPow2AddDiv2(tmp, spec);
 197         }
 198      } else {
 199         INT shift = -leadingBits;
 200         for (j=bandOffset[i];j<bandOffset[i+1];j++){
 201            spec = mdctSpectrum[j]>>shift;
 202            tmp = fPow2AddDiv2(tmp, spec);
 203         }
 204      }
 205      bandEnergy[i] = tmp<<1;
 206   }
 207
 208   /* calculate ld of bandNrg, subtract scaling */
 209   LdDataVector(bandEnergy, bandEnergyLdData, numBands);
 210   for(i=numBands; i--!=0; ) {
 211       FIXP_DBL scaleDiff = (sfbMaxScaleSpec[i]-4)*FL2FXCONST_DBL(2.0/64);
 212
 213       bandEnergyLdData[i] = (bandEnergyLdData[i] >= ((FL2FXCONST_DBL(-1.f)>>1) + (scaleDiff>>1)))
 214                           ? bandEnergyLdData[i]-scaleDiff : FL2FXCONST_DBL(-1.f);
 215       /* find maxNrgLd */
 216       maxNrgLd = fixMax(maxNrgLd, bandEnergyLdData[i]);
 217   }
 218
 219   if (maxNrgLd<=(FIXP_DBL)0)
 220   {
 221      for(i=numBands; i--!=0; )
 222      {
 223          INT scale = fixMin((sfbMaxScaleSpec[i]-4)<<1,(DFRACT_BITS-1));
 224          bandEnergy[i] = scaleValue(bandEnergy[i], -scale);
 225      }
 226      return 0;
 227   }
 228   else
 229   {  /* scale down NRGs */
 230      while (maxNrgLd>FL2FXCONST_DBL(0.0f))
 231      {
 232         maxNrgLd -=  FL2FXCONST_DBL(2.0/64);
 233         shiftBits++;
 234      }
 235      for(i=numBands; i--!=0; )
 236      {
 237          INT scale = fixMin( ((sfbMaxScaleSpec[i]-4)+shiftBits)<<1, (DFRACT_BITS-1));
 238          bandEnergyLdData[i] -= shiftBits*FL2FXCONST_DBL(2.0/64);
 239          bandEnergy[i] = scaleValue(bandEnergy[i], -scale);
 240      }
 241      return shiftBits;
 242   }
 243 }
 244
 245
 246 /*****************************************************************************
 247   functionname: FDKaacEnc_CalcBandEnergyOptimShort
 248   description:
 249   input:
 250   output:
 251 *****************************************************************************/
 252 void
 253 FDKaacEnc_CalcBandEnergyOptimShort(const FIXP_DBL *RESTRICT mdctSpectrum,
 254                                    INT            *RESTRICT sfbMaxScaleSpec,
 255                                    const INT      *RESTRICT bandOffset,
 256                                    const INT       numBands,
 257                                    FIXP_DBL       *RESTRICT bandEnergy)
 258 {
 259   INT i, j;
 260
 261   for(i=0; i<numBands; i++)
 262   {
 263     int leadingBits = sfbMaxScaleSpec[i]-3;            /* max sfbWidth = 36 ; 2^6=64 => 6/2 = 3 (spc*spc) */
 264     FIXP_DBL tmp = FL2FXCONST_DBL(0.0);
 265     for (j=bandOffset[i];j<bandOffset[i+1];j++)
 266     {
 267        FIXP_DBL spec = scaleValue(mdctSpectrum[j],leadingBits);
 268        tmp = fPow2AddDiv2(tmp, spec);
 269     }
 270     bandEnergy[i] = tmp;
 271   }
 272
 273   for(i=0; i<numBands; i++)
 274   {
 275       INT scale = (2*(sfbMaxScaleSpec[i]-3))-1;         /* max sfbWidth = 36 ; 2^6=64 => 6/2 = 3 (spc*spc) */
 276       scale = fixMax(fixMin(scale,(DFRACT_BITS-1)),-(DFRACT_BITS-1));
 277       bandEnergy[i] = scaleValueSaturate(bandEnergy[i], -scale);
 278   }
 279 }
 280
 281
 282 /*****************************************************************************
 283   functionname: FDKaacEnc_CalcBandNrgMSOpt
 284   description:
 285   input:
 286   output:
 287 *****************************************************************************/
 288 void FDKaacEnc_CalcBandNrgMSOpt(const FIXP_DBL   *RESTRICT mdctSpectrumLeft,
 289                                 const FIXP_DBL   *RESTRICT mdctSpectrumRight,
 290                                 INT              *RESTRICT sfbMaxScaleSpecLeft,
 291                                 INT              *RESTRICT sfbMaxScaleSpecRight,
 292                                 const INT        *RESTRICT bandOffset,
 293                                 const INT         numBands,
 294                                 FIXP_DBL         *RESTRICT bandEnergyMid,
 295                                 FIXP_DBL         *RESTRICT bandEnergySide,
 296                                 INT               calcLdData,
 297                                 FIXP_DBL         *RESTRICT bandEnergyMidLdData,
 298                                 FIXP_DBL         *RESTRICT bandEnergySideLdData)
 299 {
 300   INT i, j, minScale;
 301   FIXP_DBL NrgMid, NrgSide, specm, specs;
 302
 303   for (i=0; i<numBands; i++) {
 304
 305     NrgMid = NrgSide = FL2FXCONST_DBL(0.0);
 306     minScale = fixMin(sfbMaxScaleSpecLeft[i], sfbMaxScaleSpecRight[i])-4;
 307     minScale = fixMax(0, minScale);
 308
 309     if (minScale > 0) {
 310       for (j=bandOffset[i];j<bandOffset[i+1];j++) {
 311           FIXP_DBL specL = mdctSpectrumLeft[j]<<(minScale-1);
 312           FIXP_DBL specR = mdctSpectrumRight[j]<<(minScale-1);
 313           specm = specL + specR;
 314           specs = specL - specR;
 315           NrgMid = fPow2AddDiv2(NrgMid, specm);
 316           NrgSide = fPow2AddDiv2(NrgSide, specs);
 317       }
 318     } else {
 319       for (j=bandOffset[i];j<bandOffset[i+1];j++) {
 320           FIXP_DBL specL = mdctSpectrumLeft[j]>>1;
 321           FIXP_DBL specR = mdctSpectrumRight[j]>>1;
 322           specm = specL + specR;
 323           specs = specL - specR;
 324           NrgMid = fPow2AddDiv2(NrgMid, specm);
 325           NrgSide = fPow2AddDiv2(NrgSide, specs);
 326       }
 327     }
 328     bandEnergyMid[i] = NrgMid<<1;
 329     bandEnergySide[i] = NrgSide<<1;
 330   }
 331
 332   if(calcLdData) {
 333     LdDataVector(bandEnergyMid, bandEnergyMidLdData, numBands);
 334     LdDataVector(bandEnergySide, bandEnergySideLdData, numBands);
 335   }
 336
 337   for (i=0; i<numBands; i++)
 338   {
 339     INT minScale = fixMin(sfbMaxScaleSpecLeft[i], sfbMaxScaleSpecRight[i]);
 340     INT scale = fixMax(0, 2*(minScale-4));
 341
 342     if (calcLdData)
 343     {
 344        /* using the minimal scaling of left and right channel can cause very small energies;
 345        check ldNrg before subtract scaling multiplication: fract*INT we don't need fMult */
 346
 347        int minus = scale*FL2FXCONST_DBL(1.0/64);
 348
 349        if (bandEnergyMidLdData[i] != FL2FXCONST_DBL(-1.0f))
 350          bandEnergyMidLdData[i] -= minus;
 351
 352        if (bandEnergySideLdData[i] != FL2FXCONST_DBL(-1.0f))
 353          bandEnergySideLdData[i] -= minus;
 354     }
 355     scale = fixMin(scale, (DFRACT_BITS-1));
 356     bandEnergyMid[i]  >>= scale;
 357     bandEnergySide[i] >>= scale;
 358   }
 359 }