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      1 
      2 /* -----------------------------------------------------------------------------------------------------------
      3 Software License for The Fraunhofer FDK AAC Codec Library for Android
      4 
      5  Copyright  1995 - 2013 Fraunhofer-Gesellschaft zur Frderung der angewandten Forschung e.V.
      6   All rights reserved.
      7 
      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.
     24 
     25 Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality,
     26 are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional
     27 applications information and documentation.
     28 
     29 2.    COPYRIGHT LICENSE
     30 
     31 Redistribution and use in source and binary forms, with or without modification, are permitted without
     32 payment of copyright license fees provided that you satisfy the following conditions:
     33 
     34 You must retain the complete text of this software license in redistributions of the FDK AAC Codec or
     35 your modifications thereto in source code form.
     36 
     37 You must retain the complete text of this software license in the documentation and/or other materials
     38 provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form.
     39 You must make available free of charge copies of the complete source code of the FDK AAC Codec and your
     40 modifications thereto to recipients of copies in binary form.
     41 
     42 The name of Fraunhofer may not be used to endorse or promote products derived from this library without
     43 prior written permission.
     44 
     45 You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec
     46 software or your modifications thereto.
     47 
     48 Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software
     49 and the date of any change. For modified versions of the FDK AAC Codec, the term
     50 "Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term
     51 "Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android."
     52 
     53 3.    NO PATENT LICENSE
     54 
     55 NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer,
     56 ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with
     57 respect to this software.
     58 
     59 You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized
     60 by appropriate patent licenses.
     61 
     62 4.    DISCLAIMER
     63 
     64 This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors
     65 "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties
     66 of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
     67 CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages,
     68 including but not limited to procurement of substitute goods or services; loss of use, data, or profits,
     69 or business interruption, however caused and on any theory of liability, whether in contract, strict
     70 liability, or tort (including negligence), arising in any way out of the use of this software, even if
     71 advised of the possibility of such damage.
     72 
     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 (at) 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 
    386