libAACdec/src/aacdec_tns.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.
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  18 Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
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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
  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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  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: temporal noise shaping tool
  88
  89 ******************************************************************************/
  90
  91 #include "aacdec_tns.h"
  92 #include "aac_rom.h"
  93 #include "FDK_bitstream.h"
  94 #include "channelinfo.h"
  95
  96
  97
  98 /*!
  99   \brief Reset tns data
 100
 101   The function resets the tns data
 102
 103   \return  none
 104 */
 105 void CTns_Reset(CTnsData *pTnsData)
 106 {
 107   /* Note: the following FDKmemclear should not be required. */
 108   FDKmemclear(pTnsData->Filter, TNS_MAX_WINDOWS*TNS_MAXIMUM_FILTERS*sizeof(CFilter));
 109   FDKmemclear(pTnsData->NumberOfFilters, TNS_MAX_WINDOWS*sizeof(UCHAR));
 110   pTnsData->DataPresent = 0;
 111   pTnsData->Active = 0;
 112 }
 113
 114 void CTns_ReadDataPresentFlag(HANDLE_FDK_BITSTREAM bs,    /*!< pointer to bitstream */
 115                               CTnsData *pTnsData)         /*!< pointer to aac decoder channel info */
 116 {
 117   pTnsData->DataPresent = (UCHAR) FDKreadBits(bs,1);
 118 }
 119
 120 /*!
 121   \brief Read tns data from bitstream
 122
 123   The function reads the elements for tns from
 124   the bitstream.
 125
 126   \return  none
 127 */
 128 AAC_DECODER_ERROR CTns_Read(HANDLE_FDK_BITSTREAM bs,
 129                             CTnsData *pTnsData,
 130                             const CIcsInfo *pIcsInfo,
 131                             const UINT flags)
 132 {
 133   UCHAR n_filt,order;
 134   UCHAR length,coef_res,coef_compress;
 135   UCHAR window;
 136   UCHAR wins_per_frame = GetWindowsPerFrame(pIcsInfo);
 137   UCHAR isLongFlag = IsLongBlock(pIcsInfo);
 138   AAC_DECODER_ERROR ErrorStatus = AAC_DEC_OK;
 139
 140   if (!pTnsData->DataPresent) {
 141     return ErrorStatus;
 142   }
 143
 144   for (window = 0; window < wins_per_frame; window++)
 145   {
 146     pTnsData->NumberOfFilters[window] = n_filt = (UCHAR) FDKreadBits(bs, isLongFlag ? 2 : 1);
 147
 148     if (pTnsData->NumberOfFilters[window] > TNS_MAXIMUM_FILTERS){
 149         pTnsData->NumberOfFilters[window] = n_filt = TNS_MAXIMUM_FILTERS;
 150     }
 151
 152     if (n_filt)
 153     {
 154       int index;
 155       UCHAR nextstopband;
 156
 157       coef_res = (UCHAR) FDKreadBits(bs,1);
 158
 159       nextstopband = GetScaleFactorBandsTotal(pIcsInfo);
 160
 161       for (index=0; index < n_filt; index++)
 162       {
 163         CFilter *filter = &pTnsData->Filter[window][index];
 164
 165         length = (UCHAR)FDKreadBits(bs, isLongFlag ? 6 : 4);
 166
 167         if (length > nextstopband){
 168           length = nextstopband;
 169         }
 170
 171         filter->StartBand = nextstopband - length;
 172         filter->StopBand  = nextstopband;
 173         nextstopband = filter->StartBand;
 174
 175         {
 176           filter->Order = order = (UCHAR) FDKreadBits(bs, isLongFlag ? 5 : 3);
 177         }
 178
 179         if (filter->Order > TNS_MAXIMUM_ORDER){
 180           filter->Order = order = TNS_MAXIMUM_ORDER;
 181         }
 182
 183         if (order)
 184         {
 185           UCHAR coef,s_mask;
 186           UCHAR i;
 187           SCHAR n_mask;
 188           static const UCHAR sgn_mask[] = {  0x2,  0x4,  0x8 };
 189           static const SCHAR neg_mask[] = { ~0x3, ~0x7, ~0xF };
 190
 191           filter->Direction = FDKreadBits(bs,1) ? -1 : 1;
 192
 193           coef_compress = (UCHAR) FDKreadBits(bs,1);
 194
 195           filter->Resolution = coef_res + 3;
 196
 197           s_mask = sgn_mask[coef_res + 1 - coef_compress];
 198           n_mask = neg_mask[coef_res + 1 - coef_compress];
 199
 200           for (i=0; i < order; i++)
 201           {
 202             coef = (UCHAR) FDKreadBits(bs,filter->Resolution - coef_compress);
 203             filter->Coeff[i] = (coef & s_mask) ? (coef | n_mask) : coef;
 204           }
 205         }
 206       }
 207     }
 208   }
 209
 210   pTnsData->Active = 1;
 211
 212   return ErrorStatus;
 213 }
 214
 215
 216 static void CTns_Filter (FIXP_DBL *spec, int size, int inc, FIXP_TCC coeff [], int order)
 217 {
 218   // - Simple all-pole filter of order "order" defined by
 219   //   y(n) =  x(n) - a(2)*y(n-1) - ... - a(order+1)*y(n-order)
 220   //
 221   // - The state variables of the filter are initialized to zero every time
 222   //
 223   // - The output data is written over the input data ("in-place operation")
 224   //
 225   // - An input vector of "size" samples is processed and the index increment
 226   //   to the next data sample is given by "inc"
 227
 228   int i,j,N;
 229   FIXP_DBL *pSpec;
 230   FIXP_DBL maxVal=FL2FXCONST_DBL(0.0);
 231   INT s;
 232
 233   FDK_ASSERT(order <= TNS_MAXIMUM_ORDER);
 234   C_ALLOC_SCRATCH_START(state, FIXP_DBL, TNS_MAXIMUM_ORDER);
 235   FDKmemclear(state, order*sizeof(FIXP_DBL));
 236
 237   for (i=0; i<size; i++) {
 238     maxVal = fixMax(maxVal,fixp_abs(spec[i]));
 239   }
 240
 241   if ( maxVal > FL2FXCONST_DBL(0.03125*0.70710678118) )
 242     s = fixMax(CntLeadingZeros(maxVal)-6,0);
 243   else
 244     s = fixMax(CntLeadingZeros(maxVal)-5,0);
 245
 246   s = fixMin(s,2);
 247   s = s-1;
 248
 249   if (inc == -1)
 250     pSpec = &spec[size - 1];
 251   else
 252     pSpec = &spec[0];
 253
 254   FIXP_TCC *pCoeff;
 255
 256 #define FIRST_PART_FLTR                                              \
 257     FIXP_DBL x, *pState = state;                                     \
 258     pCoeff = coeff;                                                  \
 259                                                                      \
 260     if (s < 0)                                                       \
 261       x = (pSpec [0]>>1) + fMultDiv2 (*pCoeff++, pState [0]) ;       \
 262     else                                                             \
 263       x = (pSpec [0]<<s) + fMultDiv2 (*pCoeff++, pState [0]) ;
 264
 265 #define INNER_FLTR_INLINE                                            \
 266       x = fMultAddDiv2 (x, *pCoeff, pState [1]);                     \
 267       pState [0] = pState [1] - (fMultDiv2 (*pCoeff++, x) <<2) ;     \
 268       pState++;
 269
 270 #define LAST_PART_FLTR                                               \
 271       if (s < 0)                                                     \
 272         *pSpec = x << 1;                                             \
 273       else                                                           \
 274         *pSpec = x >> s;                                             \
 275       *pState =(-x) << 1;                                            \
 276       pSpec   += inc ;
 277
 278
 279    if (order>8)
 280    {
 281       N = (order-1)&7;
 282
 283       for (i = size ; i != 0 ; i--)
 284       {
 285         FIRST_PART_FLTR
 286
 287         for (j = N; j > 0 ; j--) { INNER_FLTR_INLINE }
 288
 289         INNER_FLTR_INLINE INNER_FLTR_INLINE INNER_FLTR_INLINE INNER_FLTR_INLINE
 290         INNER_FLTR_INLINE INNER_FLTR_INLINE INNER_FLTR_INLINE INNER_FLTR_INLINE
 291
 292         LAST_PART_FLTR
 293       }
 294
 295    } else if (order>4) {
 296
 297       N = (order-1)&3;
 298
 299       for (i = size ; i != 0 ; i--)
 300       {
 301         FIRST_PART_FLTR
 302         for (j = N; j > 0 ; j--) { INNER_FLTR_INLINE }
 303
 304         INNER_FLTR_INLINE INNER_FLTR_INLINE INNER_FLTR_INLINE INNER_FLTR_INLINE
 305
 306         LAST_PART_FLTR
 307       }
 308
 309    } else {
 310
 311       N = order-1;
 312
 313       for (i = size ; i != 0 ; i--)
 314       {
 315         FIRST_PART_FLTR
 316
 317         for (j = N; j > 0 ; j--) { INNER_FLTR_INLINE }
 318
 319         LAST_PART_FLTR
 320       }
 321    }
 322
 323    C_ALLOC_SCRATCH_END(state, FIXP_DBL, TNS_MAXIMUM_ORDER);
 324 }
 325
 326 /*!
 327   \brief Apply tns to spectral lines
 328
 329   The function applies the tns to the spectrum,
 330
 331   \return  none
 332 */
 333 void CTns_Apply (
 334         CTnsData *RESTRICT pTnsData, /*!< pointer to aac decoder info */
 335         const CIcsInfo *pIcsInfo,
 336         SPECTRAL_PTR pSpectralCoefficient,
 337         const SamplingRateInfo *pSamplingRateInfo,
 338         const INT granuleLength
 339         )
 340 {
 341   int window,index,start,stop,size;
 342
 343
 344   if (pTnsData->Active)
 345   {
 346       C_AALLOC_SCRATCH_START(coeff, FIXP_TCC, TNS_MAXIMUM_ORDER);
 347
 348       for (window=0; window < GetWindowsPerFrame(pIcsInfo); window++)
 349       {
 350         FIXP_DBL *pSpectrum = SPEC(pSpectralCoefficient, window, granuleLength);
 351
 352         for (index=0; index < pTnsData->NumberOfFilters[window]; index++)
 353         {
 354           CFilter *RESTRICT filter = &pTnsData->Filter[window][index];
 355
 356           if (filter->Order > 0)
 357           {
 358              FIXP_TCC *pCoeff;
 359              int tns_max_bands;
 360
 361              pCoeff = &coeff[filter->Order-1];
 362              if (filter->Resolution == 3)
 363              {
 364                int i;
 365                for (i=0; i < filter->Order; i++)
 366                  *pCoeff-- = FDKaacDec_tnsCoeff3[filter->Coeff[i]+4];
 367              }
 368              else
 369              {
 370                int i;
 371                for (i=0; i < filter->Order; i++)
 372                  *pCoeff-- = FDKaacDec_tnsCoeff4[filter->Coeff[i]+8];
 373              }
 374
 375              switch (granuleLength) {
 376                case 480:
 377                  tns_max_bands = tns_max_bands_tbl_480[pSamplingRateInfo->samplingRateIndex];
 378                  break;
 379                case 512:
 380                  tns_max_bands = tns_max_bands_tbl_512[pSamplingRateInfo->samplingRateIndex];
 381                  break;
 382                default:
 383                  tns_max_bands = GetMaximumTnsBands(pIcsInfo, pSamplingRateInfo->samplingRateIndex);
 384                  break;
 385              }
 386
 387              start = fixMin( fixMin(filter->StartBand, tns_max_bands),
 388                              GetScaleFactorBandsTransmitted(pIcsInfo) );
 389
 390              start = GetScaleFactorBandOffsets(pIcsInfo, pSamplingRateInfo)[start];
 391
 392              stop = fixMin( fixMin(filter->StopBand, tns_max_bands),
 393                             GetScaleFactorBandsTransmitted(pIcsInfo) );
 394
 395              stop = GetScaleFactorBandOffsets(pIcsInfo, pSamplingRateInfo)[stop];
 396
 397              size = stop - start;
 398
 399              if (size > 0) {
 400                CTns_Filter(&pSpectrum[start],
 401                             size,
 402                             filter->Direction,
 403                             coeff,
 404                             filter->Order );
 405              }
 406           }
 407         }
 408       }
 409       C_AALLOC_SCRATCH_END(coeff, FIXP_TCC, TNS_MAXIMUM_ORDER);
 410   }
 411
 412 }