libFDK/src/mdct.cpp

   1
   2 /* -----------------------------------------------------------------------------------------------------------
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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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  81 amm-info@iis.fraunhofer.de
  82 ----------------------------------------------------------------------------------------------------------- */
  83
  84 /***************************  Fraunhofer IIS FDK Tools  **********************
  85
  86    Author(s):   Josef Hoepfl, Manuel Jander
  87    Description: MDCT routines
  88
  89 ******************************************************************************/
  90
  91 #include "mdct.h"
  92
  93
  94 #include "FDK_tools_rom.h"
  95 #include "dct.h"
  96 #include "fixpoint_math.h"
  97
  98
  99 void mdct_init( H_MDCT hMdct,
 100                 FIXP_DBL *overlap,
 101                 INT overlapBufferSize )
 102 {
 103   hMdct->overlap.freq = overlap;
 104   //FDKmemclear(overlap, overlapBufferSize*sizeof(FIXP_DBL));
 105   hMdct->prev_fr = 0;
 106   hMdct->prev_nr = 0;
 107   hMdct->prev_tl = 0;
 108   hMdct->ov_size = overlapBufferSize;
 109 }
 110
 111
 112 void imdct_gain(FIXP_DBL *pGain_m, int *pGain_e, int tl)
 113 {
 114   FIXP_DBL gain_m = *pGain_m;
 115   int gain_e = *pGain_e;
 116   int log2_tl;
 117
 118   log2_tl = DFRACT_BITS-1-fNormz((FIXP_DBL)tl);
 119
 120   gain_e += -MDCT_OUTPUT_GAIN - log2_tl - MDCT_OUT_HEADROOM + 1;
 121
 122   /* Detect non-radix 2 transform length and add amplitude compensation factor
 123      which cannot be included into the exponent above */
 124   switch ( (tl) >> (log2_tl - 2) ) {
 125     case 0x7: /* 10 ms, 1/tl = 1.0/(FDKpow(2.0, -log2_tl) * 0.53333333333333333333) */
 126       if (gain_m == (FIXP_DBL)0) {
 127         gain_m = FL2FXCONST_DBL(0.53333333333333333333f);
 128       } else {
 129         gain_m = fMult(gain_m, FL2FXCONST_DBL(0.53333333333333333333f));
 130       }
 131       break;
 132     case 0x6: /* 3/4 of radix 2, 1/tl = 1.0/(FDKpow(2.0, -log2_tl) * 2.0/3.0) */
 133       if (gain_m == (FIXP_DBL)0) {
 134         gain_m = FL2FXCONST_DBL(2.0/3.0f);
 135       } else {
 136         gain_m = fMult(gain_m, FL2FXCONST_DBL(2.0/3.0f));
 137       }
 138       break;
 139     case 0x4:
 140       /* radix 2, nothing to do. */
 141       break;
 142     default:
 143       /* unsupported */
 144       FDK_ASSERT(0);
 145       break;
 146   }
 147
 148   *pGain_m = gain_m;
 149   *pGain_e = gain_e;
 150 }
 151
 152 INT imdct_drain(
 153         H_MDCT hMdct,
 154         FIXP_DBL *output,
 155         INT nrSamplesRoom
 156         )
 157 {
 158   int buffered_samples = 0;
 159
 160   if (nrSamplesRoom > 0) {
 161     buffered_samples = hMdct->ov_offset;
 162
 163     FDK_ASSERT(buffered_samples <= nrSamplesRoom);
 164
 165     if (buffered_samples > 0)  {
 166       FDKmemcpy(output, hMdct->overlap.time, buffered_samples*sizeof(FIXP_DBL));
 167       hMdct->ov_offset = 0;
 168     }
 169   }
 170   return buffered_samples;
 171 }
 172
 173 INT imdct_copy_ov_and_nr(
 174         H_MDCT hMdct,
 175         FIXP_DBL * pTimeData,
 176         INT nrSamples
 177         )
 178 {
 179   FIXP_DBL *pOvl;
 180   int nt, nf, i;
 181
 182   nt = fMin(hMdct->ov_offset, nrSamples);
 183   nrSamples -= nt;
 184   nf = fMin(hMdct->prev_nr, nrSamples);
 185   nrSamples -= nf;
 186   FDKmemcpy(pTimeData, hMdct->overlap.time, nt*sizeof(FIXP_DBL));
 187   pTimeData += nt;
 188
 189   pOvl = hMdct->overlap.freq + hMdct->ov_size - 1;
 190   for (i=0; i<nf; i++) {
 191     FIXP_DBL x = - (*pOvl--);
 192     *pTimeData = IMDCT_SCALE_DBL(x);
 193     pTimeData ++;
 194   }
 195
 196   return (nt+nf);
 197 }
 198
 199 void imdct_adapt_parameters(H_MDCT hMdct, int *pfl, int *pnl, int tl, const FIXP_WTP *wls, int noOutSamples)
 200 {
 201   int fl = *pfl, nl = *pnl;
 202   int window_diff, use_current = 0, use_previous = 0;
 203   if (hMdct->prev_tl == 0) {
 204     hMdct->prev_wrs    = wls;
 205     hMdct->prev_fr     = fl;
 206     hMdct->prev_nr     = (noOutSamples-fl)>>1;
 207     hMdct->prev_tl     = noOutSamples;
 208     hMdct->ov_offset   = 0;
 209     use_current = 1;
 210   }
 211
 212   window_diff = (hMdct->prev_fr - fl)>>1;
 213
 214   /* check if the previous window slope can be adjusted to match the current window slope */
 215   if (hMdct->prev_nr + window_diff > 0) {
 216     use_current = 1;
 217   }
 218   /* check if the current window slope can be adjusted to match the previous window slope */
 219   if (nl - window_diff > 0 ) {
 220     use_previous = 1;
 221   }
 222
 223   /* if both is possible choose the larger of both window slope lengths */
 224   if (use_current && use_previous) {
 225     if (fl < hMdct->prev_fr) {
 226       use_current = 0;
 227     } else {
 228       use_previous = 0;
 229     }
 230   }
 231   /*
 232    * If the previous transform block is big enough, enlarge previous window overlap,
 233    * if not, then shrink current window overlap.
 234    */
 235   if (use_current) {
 236     hMdct->prev_nr += window_diff;
 237     hMdct->prev_fr = fl;
 238     hMdct->prev_wrs = wls;
 239   } else {
 240     nl -= window_diff;
 241     fl = hMdct->prev_fr;
 242   }
 243
 244   *pfl = fl;
 245   *pnl = nl;
 246 }
 247
 248 INT  imdct_block(
 249         H_MDCT hMdct,
 250         FIXP_DBL *output,
 251         FIXP_DBL *spectrum,
 252         const SHORT scalefactor[],
 253         const INT nSpec,
 254         const INT noOutSamples,
 255         const INT tl,
 256         const FIXP_WTP *wls,
 257         INT fl,
 258         const FIXP_WTP *wrs,
 259         const INT fr,
 260         FIXP_DBL gain
 261         )
 262 {
 263   FIXP_DBL *pOvl;
 264   FIXP_DBL *pOut0 = output, *pOut1;
 265   INT nl, nr;
 266   int w, i, nrSamples = 0, specShiftScale, transform_gain_e = 0;
 267
 268   /* Derive NR and NL */
 269   nr = (tl - fr)>>1;
 270   nl = (tl - fl)>>1;
 271
 272   /* Include 2/N IMDCT gain into gain factor and exponent. */
 273   imdct_gain(&gain, &transform_gain_e, tl);
 274
 275   /* Detect FRprevious / FL mismatches and override parameters accordingly */
 276   if (hMdct->prev_fr != fl) {
 277     imdct_adapt_parameters(hMdct, &fl, &nl, tl, wls, noOutSamples);
 278   }
 279
 280   pOvl = hMdct->overlap.freq + hMdct->ov_size - 1;
 281
 282   if ( noOutSamples > nrSamples ) {
 283     /* Purge buffered output. */
 284     for (i=0; i<hMdct->ov_offset; i++) {
 285       *pOut0 = hMdct->overlap.time[i];
 286       pOut0 ++;
 287     }
 288     nrSamples = hMdct->ov_offset;
 289     hMdct->ov_offset = 0;
 290   }
 291
 292   for (w=0; w<nSpec; w++)
 293   {
 294     FIXP_DBL *pSpec, *pCurr;
 295     const FIXP_WTP *pWindow;
 296
 297     specShiftScale = transform_gain_e;
 298
 299     /* Setup window pointers */
 300     pWindow = hMdct->prev_wrs;
 301
 302     /* Current spectrum */
 303     pSpec = spectrum+w*tl;
 304
 305     /* DCT IV of current spectrum. */
 306     dct_IV(pSpec, tl, &specShiftScale);
 307
 308     /* Optional scaling of time domain - no yet windowed - of current spectrum */
 309     /* and de-scale current spectrum signal (time domain, no yet windowed) */
 310     if (gain != (FIXP_DBL)0) {
 311       scaleValuesWithFactor(pSpec, gain, tl, scalefactor[w] + specShiftScale);
 312     } else {
 313       scaleValues(pSpec, tl, scalefactor[w] + specShiftScale);
 314     }
 315
 316     if ( noOutSamples <= nrSamples ) {
 317       /* Divert output first half to overlap buffer if we already got enough output samples. */
 318       pOut0 = hMdct->overlap.time + hMdct->ov_offset;
 319       hMdct->ov_offset += hMdct->prev_nr + fl/2;
 320     } else {
 321       /* Account output samples */
 322       nrSamples += hMdct->prev_nr + fl/2;
 323     }
 324
 325     /* NR output samples 0 .. NR. -overlap[TL/2..TL/2-NR] */
 326     for (i=0; i<hMdct->prev_nr; i++) {
 327       FIXP_DBL x = - (*pOvl--);
 328       *pOut0 = IMDCT_SCALE_DBL(x);
 329       pOut0 ++;
 330     }
 331
 332     if ( noOutSamples <= nrSamples ) {
 333       /* Divert output second half to overlap buffer if we already got enough output samples. */
 334       pOut1 = hMdct->overlap.time + hMdct->ov_offset + fl/2 - 1;
 335       hMdct->ov_offset += fl/2 + nl;
 336     } else {
 337       pOut1 = pOut0 + (fl - 1);
 338       nrSamples += fl/2 + nl;
 339     }
 340
 341     /* output samples before window crossing point NR .. TL/2. -overlap[TL/2-NR..TL/2-NR-FL/2] + current[NR..TL/2] */
 342     /* output samples after window crossing point TL/2 .. TL/2+FL/2. -overlap[0..FL/2] - current[TL/2..FL/2] */
 343     pCurr = pSpec + tl - fl/2;
 344     for (i=0; i<fl/2; i++) {
 345       FIXP_DBL x0, x1;
 346
 347       cplxMult(&x1, &x0, *pCurr++, - *pOvl--, pWindow[i]);
 348       *pOut0 = IMDCT_SCALE_DBL(x0);
 349       *pOut1 = IMDCT_SCALE_DBL(-x1);
 350       pOut0 ++;
 351       pOut1 --;
 352     }
 353     pOut0 += (fl/2);
 354
 355     /* NL output samples TL/2+FL/2..TL. - current[FL/2..0] */
 356     pOut1 += (fl/2) + 1;
 357     pCurr = pSpec + tl - fl/2 - 1;
 358     for (i=0; i<nl; i++) {
 359       FIXP_DBL x = - (*pCurr--);
 360       *pOut1 = IMDCT_SCALE_DBL(x);
 361       pOut1 ++;
 362     }
 363
 364     /* Set overlap source pointer for next window pOvl = pSpec + tl/2 - 1; */
 365     pOvl = pSpec + tl/2 - 1;
 366
 367     /* Previous window values. */
 368     hMdct->prev_nr = nr;
 369     hMdct->prev_fr = fr;
 370     hMdct->prev_tl = tl;
 371     hMdct->prev_wrs = wrs;
 372   }
 373
 374   /* Save overlap */
 375
 376   pOvl = hMdct->overlap.freq + hMdct->ov_size - tl/2;
 377   FDK_ASSERT(pOvl >= hMdct->overlap.time + hMdct->ov_offset);
 378   FDK_ASSERT(tl/2 <= hMdct->ov_size);
 379   for (i=0; i<tl/2; i++) {
 380     pOvl[i] = spectrum[i+(nSpec-1)*tl];
 381   }
 382
 383   return nrSamples;
 384 }
 385