libAACenc/src/transform.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)
  19 may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners
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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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  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 /*****************************************************************************
  85
  86    Description: FDKaacLdEnc_MdctTransform480:
  87                 The module FDKaacLdEnc_MdctTransform will perform the MDCT.
  88                 The MDCT supports the sine window and
  89                 the zero padded window. The algorithm of the MDCT
  90                 can be divided in  Windowing, PreModulation, Fft and
  91                 PostModulation.
  92
  93 ******************************************************************************/
  94
  95 #include "transform.h"
  96
  97 #include "dct.h"
  98 #include "psy_const.h"
  99 #include "aacEnc_rom.h"
 100 #include "FDK_tools_rom.h"
 101
 102 INT FDKaacEnc_Transform_Real (const INT_PCM * pTimeData,
 103                               FIXP_DBL *RESTRICT mdctData,
 104                               const INT blockType,
 105                               const INT windowShape,
 106                               INT *prevWindowShape,
 107                               const INT frameLength,
 108                               INT *mdctData_e,
 109                               INT filterType
 110                              ,FIXP_DBL * RESTRICT overlapAddBuffer
 111                              )
 112 {
 113   const INT_PCM * RESTRICT timeData;
 114
 115   INT i;
 116   /* tl: transform length
 117      fl: left window slope length
 118      nl: left window slope offset
 119      fr: right window slope length
 120      nr: right window slope offset
 121      See FDK_tools/doc/intern/mdct.tex for more detail. */
 122   int tl, fl, nl, fr, nr;
 123
 124   const FIXP_WTP * RESTRICT pLeftWindowPart;
 125   const FIXP_WTP * RESTRICT pRightWindowPart;
 126
 127   /*
 128    * MDCT scale:
 129    * + 1: fMultDiv2() in windowing.
 130    * + 1: Because of factor 1/2 in Princen-Bradley compliant windowed TDAC.
 131    */
 132   *mdctData_e = 1+1;
 133
 134   tl = frameLength;
 135   timeData = pTimeData;
 136
 137   switch( blockType ) {
 138     case LONG_WINDOW:
 139       {
 140         int offset = (windowShape == LOL_WINDOW) ? ((frameLength * 3)>>2) : 0;
 141         fl = frameLength - offset;
 142         fr = frameLength - offset;
 143       }
 144       break;
 145     case STOP_WINDOW:
 146       fl = frameLength >> 3;
 147       fr = frameLength;
 148       break;
 149     case START_WINDOW: /* or StopStartSequence */
 150       fl = frameLength;
 151       fr = frameLength >> 3;
 152       break;
 153     case SHORT_WINDOW:
 154       fl = fr = frameLength >> 3;
 155       tl >>= 3;
 156       timeData = pTimeData + 3*fl + (fl/2);
 157       break;
 158     default:
 159       FDK_ASSERT(0);
 160       return -1;
 161       break;
 162   }
 163
 164   /* Taken from FDK_tools/src/mdct.cpp Derive NR and NL */
 165   nr = (tl - fr)>>1;
 166   nl = (tl - fl)>>1;
 167
 168   pLeftWindowPart = FDKgetWindowSlope(fl, *prevWindowShape);
 169   pRightWindowPart = FDKgetWindowSlope(fr, windowShape);
 170
 171   /* windowing */
 172   if (filterType != FB_ELD)
 173   {
 174     /* Left window slope offset */
 175     for (i=0; i<nl ; i++)
 176     {
 177 #if SAMPLE_BITS == DFRACT_BITS   /* SPC_BITS and DFRACT_BITS should be equal. */
 178       mdctData[(tl/2)+i] = - (FIXP_DBL) timeData[tl-i-1] >> ( 1 );
 179 #else
 180       mdctData[(tl/2)+i] = - (FIXP_DBL) timeData[tl-i-1] << (DFRACT_BITS - SAMPLE_BITS - 1);
 181 #endif
 182     }
 183     /* Left window slope */
 184     for (i=0; i<fl/2; i++)
 185     {
 186       FIXP_DBL tmp0;
 187       tmp0 = fMultDiv2((FIXP_PCM)timeData[i+nl], pLeftWindowPart[i].v.im);
 188       mdctData[(tl/2)+i+nl] = fMultSubDiv2(tmp0, (FIXP_PCM)timeData[tl-nl-i-1], pLeftWindowPart[i].v.re);
 189     }
 190
 191     /* Right window slope offset */
 192     for(i=0; i<nr; i++)
 193     {
 194 #if SAMPLE_BITS == DFRACT_BITS    /* This should be SPC_BITS instead of DFRACT_BITS. */
 195       mdctData[(tl/2)-1-i] = - (FIXP_DBL) timeData[tl+i] >> (1);
 196 #else
 197       mdctData[(tl/2)-1-i] = - (FIXP_DBL) timeData[tl+i] << (DFRACT_BITS - SAMPLE_BITS - 1);
 198 #endif
 199     }
 200     /* Right window slope */
 201     for (i=0; i<fr/2; i++)
 202     {
 203       FIXP_DBL tmp1;
 204       tmp1 = fMultDiv2((FIXP_PCM)timeData[tl+nr+i], pRightWindowPart[i].v.re);
 205       mdctData[(tl/2)-nr-i-1] = -fMultAddDiv2(tmp1, (FIXP_PCM)timeData[(tl*2)-nr-i-1], pRightWindowPart[i].v.im);
 206     }
 207   }
 208
 209   if (filterType == FB_ELD)
 210   {
 211     const FIXP_WTB *pWindowELD=NULL;
 212     int i, N = frameLength, L = frameLength;
 213
 214     if (frameLength == 512) {
 215       pWindowELD = ELDAnalysis512;
 216     } else {
 217       pWindowELD = ELDAnalysis480;
 218     }
 219
 220     for(i=0;i<N/4;i++)
 221     {
 222       FIXP_DBL z0, outval;
 223
 224       z0 = (fMult((FIXP_PCM)timeData[L+N*3/4-1-i], pWindowELD[N/2-1-i])<< (WTS0-1)) + (fMult((FIXP_PCM)timeData[L+N*3/4+i], pWindowELD[N/2+i])<< (WTS0-1));
 225
 226       outval  = (fMultDiv2((FIXP_PCM)timeData[L+N*3/4-1-i], pWindowELD[N+N/2-1-i]) >> (-WTS1));
 227       outval += (fMultDiv2((FIXP_PCM)timeData[L+N*3/4+i], pWindowELD[N+N/2+i]) >> (-WTS1) );
 228       outval += (fMultDiv2(overlapAddBuffer[N/2+i], pWindowELD[2*N+i])>> (-WTS2-1));
 229
 230       overlapAddBuffer[N/2+i] = overlapAddBuffer[i];
 231
 232       overlapAddBuffer[i] = z0;
 233       mdctData[i] = overlapAddBuffer[N/2+i] + (fMultDiv2(overlapAddBuffer[N+N/2-1-i], pWindowELD[2*N+N/2+i]) >> (-WTS2-1));
 234
 235       mdctData[N-1-i] = outval;
 236       overlapAddBuffer[N+N/2-1-i] = outval;
 237     }
 238
 239     for(i=N/4;i<N/2;i++)
 240     {
 241       FIXP_DBL z0, outval;
 242
 243       z0 = fMult((FIXP_PCM)timeData[L+N*3/4-1-i], pWindowELD[N/2-1-i]) << (WTS0-1);
 244
 245       outval  = (fMultDiv2((FIXP_PCM)timeData[L+N*3/4-1-i], pWindowELD[N+N/2-1-i]) >> (-WTS1)) ;
 246       outval += (fMultDiv2(overlapAddBuffer[N/2+i], pWindowELD[2*N+i]) >> (-WTS2-1));
 247
 248       overlapAddBuffer[N/2+i] = overlapAddBuffer[i] + (fMult((FIXP_PCM)timeData[L-N/4+i], pWindowELD[N/2+i])<< (WTS0-1) );
 249
 250       overlapAddBuffer[i] = z0;
 251       mdctData[i] = overlapAddBuffer[N/2+i] + (fMultDiv2(overlapAddBuffer[N+N/2-1-i], pWindowELD[2*N+N/2+i]) >> (-WTS2-1));
 252
 253       mdctData[N-1-i] = outval;
 254       overlapAddBuffer[N+N/2-1-i] = outval;
 255     }
 256   }
 257
 258   dct_IV(mdctData, tl, mdctData_e);
 259
 260   *prevWindowShape = windowShape;
 261
 262   return 0;
 263 }
 264