libAACdec/src/aacdec_pns.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.
   6   All rights reserved.
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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.
  17
  18 Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
  19 may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners
  20 individually for the purpose of encoding or decoding bit streams in products that are compliant with
  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
  23 software may already be covered under those patent licenses when it is used for those licensed purposes only.
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  56 ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with
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  62 4.    DISCLAIMER
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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
  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 Decoder  **************************
  85
  86    Author(s):   Josef Hoepfl
  87    Description: perceptual noise substitution tool
  88
  89 ******************************************************************************/
  90
  91 #include "aacdec_pns.h"
  92
  93
  94 #include "aac_ram.h"
  95 #include "aac_rom.h"
  96 #include "channelinfo.h"
  97 #include "block.h"
  98 #include "FDK_bitstream.h"
  99
 100 #include "genericStds.h"
 101
 102
 103 #define NOISE_OFFSET 90           /* cf. ISO 14496-3 p. 175 */
 104
 105 /*!
 106   \brief Reset InterChannel and PNS data
 107
 108   The function resets the InterChannel and PNS data
 109 */
 110 void CPns_ResetData(
 111     CPnsData *pPnsData,
 112     CPnsInterChannelData *pPnsInterChannelData
 113     )
 114 {
 115   /* Assign pointer always, since pPnsData is not persistent data */
 116   pPnsData->pPnsInterChannelData = pPnsInterChannelData;
 117   pPnsData->PnsActive = 0;
 118   pPnsData->CurrentEnergy = 0;
 119
 120   FDKmemclear(pPnsData->pnsUsed,(8*16)*sizeof(UCHAR));
 121   FDKmemclear(pPnsInterChannelData->correlated,(8*16)*sizeof(UCHAR));
 122 }
 123
 124 /*!
 125   \brief Initialize PNS data
 126
 127   The function initializes the PNS data
 128 */
 129 void CPns_InitPns(
 130     CPnsData *pPnsData,
 131     CPnsInterChannelData *pPnsInterChannelData,
 132     INT* currentSeed, INT* randomSeed)
 133 {
 134   /* save pointer to inter channel data */
 135   pPnsData->pPnsInterChannelData = pPnsInterChannelData;
 136
 137   /* use pointer because seed has to be
 138      same, left and right channel ! */
 139   pPnsData->currentSeed = currentSeed;
 140   pPnsData->randomSeed  = randomSeed;
 141 }
 142
 143 /*!
 144   \brief Indicates if PNS is used
 145
 146   The function returns a value indicating whether PNS is used or not
 147   acordding to the noise energy
 148
 149   \return  PNS used
 150 */
 151 int CPns_IsPnsUsed (const CPnsData *pPnsData,
 152                     const int group,
 153                     const int band)
 154 {
 155   unsigned pns_band = group*16+band;
 156
 157   return pPnsData->pnsUsed[pns_band] & (UCHAR)1;
 158 }
 159
 160 /*!
 161   \brief Set correlation
 162
 163   The function activates the noise correlation between the channel pair
 164 */
 165 void CPns_SetCorrelation(CPnsData *pPnsData,
 166                          const int group,
 167                          const int band,
 168                          const int outofphase)
 169 {
 170   CPnsInterChannelData *pInterChannelData = pPnsData->pPnsInterChannelData;
 171   unsigned pns_band = group*16+band;
 172
 173   pInterChannelData->correlated[pns_band] = (outofphase) ? 3 : 1;
 174 }
 175
 176 /*!
 177   \brief Indicates if correlation is used
 178
 179   The function indicates if the noise correlation between the channel pair
 180   is activated
 181
 182   \return  PNS is correlated
 183 */
 184 static
 185 int CPns_IsCorrelated(const CPnsData *pPnsData,
 186                       const int group,
 187                       const int band)
 188 {
 189   CPnsInterChannelData *pInterChannelData = pPnsData->pPnsInterChannelData;
 190   unsigned pns_band = group*16+band;
 191
 192   return (pInterChannelData->correlated[pns_band] & 0x01) ? 1 : 0;
 193 }
 194
 195 /*!
 196   \brief Indicates if correlated out of phase mode is used.
 197
 198   The function indicates if the noise correlation between the channel pair
 199   is activated in out-of-phase mode.
 200
 201   \return  PNS is out-of-phase
 202 */
 203 static
 204 int CPns_IsOutOfPhase(const CPnsData *pPnsData,
 205                       const int group,
 206                       const int band)
 207 {
 208   CPnsInterChannelData *pInterChannelData = pPnsData->pPnsInterChannelData;
 209   unsigned pns_band = group*16+band;
 210
 211   return (pInterChannelData->correlated[pns_band] & 0x02) ? 1 : 0;
 212 }
 213
 214 /*!
 215   \brief Read PNS information
 216
 217   The function reads the PNS information from the bitstream
 218 */
 219 void CPns_Read (CPnsData *pPnsData,
 220                 HANDLE_FDK_BITSTREAM bs,
 221                 const CodeBookDescription *hcb,
 222                 SHORT *pScaleFactor,
 223                 UCHAR global_gain,
 224                 int band,
 225                 int group /* = 0 */)
 226 {
 227   int delta ;
 228   UINT pns_band = group*16+band;
 229
 230   if (pPnsData->PnsActive) {
 231     /* Next PNS band case */
 232     delta = CBlock_DecodeHuffmanWord (bs, hcb) - 60;
 233   } else {
 234     /* First PNS band case */
 235     int noiseStartValue = FDKreadBits(bs,9);
 236
 237     delta = noiseStartValue - 256 ;
 238     pPnsData->PnsActive = 1;
 239     pPnsData->CurrentEnergy = global_gain - NOISE_OFFSET;
 240   }
 241
 242   pPnsData->CurrentEnergy += delta ;
 243   pScaleFactor[pns_band] = pPnsData->CurrentEnergy;
 244
 245   pPnsData->pnsUsed[pns_band] = 1;
 246 }
 247
 248
 249 /**
 250  * \brief Generate a vector of noise of given length. The noise values are
 251  *        scaled in order to yield a noise energy of 1.0
 252  * \param spec pointer to were the noise values will be written to.
 253  * \param size amount of noise values to be generated.
 254  * \param pRandomState pointer to the state of the random generator being used.
 255  * \return exponent of generated noise vector.
 256  */
 257 static int GenerateRandomVector (FIXP_DBL *RESTRICT spec,
 258                                   int size,
 259                                   int *pRandomState)
 260 {
 261   int i, invNrg_e = 0, nrg_e = 0;
 262   FIXP_DBL invNrg_m, nrg_m = FL2FXCONST_DBL(0.0f) ;
 263   FIXP_DBL *RESTRICT ptr = spec;
 264   int randomState = *pRandomState;
 265
 266 #define GEN_NOISE_NRG_SCALE 7
 267
 268   /* Generate noise and calculate energy. */
 269   for (i=0; i<size; i++)
 270   {
 271     randomState = (1664525L * randomState) + 1013904223L; // Numerical Recipes
 272     nrg_m = fPow2AddDiv2(nrg_m, (FIXP_DBL)randomState>>GEN_NOISE_NRG_SCALE);
 273     *ptr++ = (FIXP_DBL)randomState;
 274   }
 275   nrg_e = GEN_NOISE_NRG_SCALE*2 + 1;
 276
 277   /* weight noise with = 1 / sqrt_nrg; */
 278   invNrg_m = invSqrtNorm2(nrg_m<<1, &invNrg_e);
 279   invNrg_e += -((nrg_e-1)>>1);
 280
 281   for (i=size; i--; )
 282   {
 283     spec[i] = fMult(spec[i], invNrg_m);
 284   }
 285
 286   /* Store random state */
 287   *pRandomState = randomState;
 288
 289   return invNrg_e;
 290 }
 291
 292 static void ScaleBand (FIXP_DBL *RESTRICT spec, int size, int scaleFactor, int specScale, int noise_e, int out_of_phase)
 293 {
 294   int i, shift, sfExponent;
 295   FIXP_DBL sfMatissa;
 296
 297   /* Get gain from scale factor value = 2^(scaleFactor * 0.25) */
 298   sfMatissa = MantissaTable[scaleFactor & 0x03][0];
 299   /* sfExponent = (scaleFactor >> 2) + ExponentTable[scaleFactor & 0x03][0]; */
 300   /* Note:  ExponentTable[scaleFactor & 0x03][0] is always 1. */
 301   sfExponent = (scaleFactor >> 2) + 1;
 302
 303   if (out_of_phase != 0) {
 304     sfMatissa = -sfMatissa;
 305   }
 306
 307   /* +1 because of fMultDiv2 below. */
 308   shift = sfExponent - specScale + 1 + noise_e;
 309
 310   /* Apply gain to noise values */
 311   if (shift>=0) {
 312     shift = fixMin( shift, DFRACT_BITS-1 );
 313     for (i = size ; i-- != 0; ) {
 314       spec [i] = fMultDiv2 (spec [i], sfMatissa) << shift;
 315     }
 316   } else {
 317     shift = fixMin( -shift, DFRACT_BITS-1 );
 318     for (i = size ; i-- != 0; ) {
 319       spec [i] = fMultDiv2 (spec [i], sfMatissa) >> shift;
 320     }
 321   }
 322 }
 323
 324
 325 /*!
 326   \brief Apply PNS
 327
 328   The function applies PNS (i.e. it generates noise) on the bands
 329   flagged as noisy bands
 330
 331 */
 332 void CPns_Apply (const CPnsData *pPnsData,
 333                  const CIcsInfo *pIcsInfo,
 334                  SPECTRAL_PTR pSpectrum,
 335                  const SHORT    *pSpecScale,
 336                  const SHORT    *pScaleFactor,
 337                  const SamplingRateInfo *pSamplingRateInfo,
 338                  const INT granuleLength,
 339                  const int channel)
 340 {
 341   if (pPnsData->PnsActive) {
 342     const short *BandOffsets = GetScaleFactorBandOffsets(pIcsInfo, pSamplingRateInfo);
 343
 344     int ScaleFactorBandsTransmitted = GetScaleFactorBandsTransmitted(pIcsInfo);
 345
 346     for (int window = 0, group = 0; group < GetWindowGroups(pIcsInfo); group++) {
 347       for (int groupwin = 0; groupwin < GetWindowGroupLength(pIcsInfo, group); groupwin++, window++) {
 348         FIXP_DBL *spectrum = SPEC(pSpectrum, window, granuleLength);
 349
 350         for (int band = 0 ; band < ScaleFactorBandsTransmitted; band++) {
 351           if (CPns_IsPnsUsed (pPnsData, group, band)) {
 352             UINT pns_band = group*16+band;
 353
 354             int bandWidth = BandOffsets [band + 1] - BandOffsets [band] ;
 355             int noise_e;
 356
 357             FDK_ASSERT(bandWidth >= 0);
 358
 359             if (channel > 0 && CPns_IsCorrelated(pPnsData, group, band))
 360             {
 361               noise_e = GenerateRandomVector (spectrum + BandOffsets [band], bandWidth,
 362                                     &pPnsData->randomSeed [pns_band]) ;
 363             }
 364             else
 365             {
 366               pPnsData->randomSeed [pns_band] = *pPnsData->currentSeed ;
 367
 368               noise_e = GenerateRandomVector (spectrum + BandOffsets [band], bandWidth,
 369                                     pPnsData->currentSeed) ;
 370             }
 371
 372             int outOfPhase  = CPns_IsOutOfPhase (pPnsData, group, band);
 373
 374             ScaleBand (spectrum + BandOffsets [band], bandWidth,
 375                        pScaleFactor[pns_band],
 376                        pSpecScale[window], noise_e, outOfPhase) ;
 377           }
 378         }
 379       }
 380     }
 381   }
 382 }