libAACenc/src/line_pe.cpp

   1
   2 /* -----------------------------------------------------------------------------------------------------------
   3 Software License for The Fraunhofer FDK AAC Codec Library for Android
   4
   5 © Copyright  1995 - 2013 Fraunhofer-Gesellschaft zur Förderung 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
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  31 Redistribution and use in source and binary forms, with or without modification, are permitted without
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  35 your modifications thereto in source code form.
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  38 provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form.
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  40 modifications thereto to recipients of copies in binary form.
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  46 software or your modifications thereto.
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  49 and the date of any change. For modified versions of the FDK AAC Codec, the term
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  51 "Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android."
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  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.
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  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
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  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@iis.fraunhofer.de
  82 ----------------------------------------------------------------------------------------------------------- */
  83
  84 /******************************** MPEG Audio Encoder **************************
  85
  86    Initial author:       M. Werner
  87    contents/description: Perceptual entropie module
  88
  89 ******************************************************************************/
  90
  91 #include "line_pe.h"
  92 #include "sf_estim.h"
  93 #include "bit_cnt.h"
  94
  95 #include "genericStds.h"
  96
  97 static const FIXP_DBL C1LdData = FL2FXCONST_DBL(3.0/LD_DATA_SCALING);        /* C1 = 3.0 = log(8.0)/log(2) */
  98 static const FIXP_DBL C2LdData = FL2FXCONST_DBL(1.3219281/LD_DATA_SCALING);  /* C2 = 1.3219281 = log(2.5)/log(2) */
  99 static const FIXP_DBL C3LdData = FL2FXCONST_DBL(0.5593573);                  /* 1-C2/C1 */
 100
 101
 102 /* constants that do not change during successive pe calculations */
 103 void FDKaacEnc_prepareSfbPe(PE_CHANNEL_DATA *peChanData,
 104                   const FIXP_DBL  *sfbEnergyLdData,
 105                   const FIXP_DBL  *sfbThresholdLdData,
 106                   const FIXP_DBL  *sfbFormFactorLdData,
 107                   const INT       *sfbOffset,
 108                   const INT       sfbCnt,
 109                   const INT       sfbPerGroup,
 110                   const INT       maxSfbPerGroup)
 111 {
 112    INT sfbGrp,sfb;
 113    INT sfbWidth;
 114    FIXP_DBL avgFormFactorLdData;
 115    const FIXP_DBL formFacScaling = FL2FXCONST_DBL((float)FORM_FAC_SHIFT/LD_DATA_SCALING);
 116
 117    for (sfbGrp = 0;sfbGrp < sfbCnt;sfbGrp+=sfbPerGroup) {
 118     for (sfb=0; sfb<maxSfbPerGroup; sfb++) {
 119       if ((FIXP_DBL)sfbEnergyLdData[sfbGrp+sfb] > (FIXP_DBL)sfbThresholdLdData[sfbGrp+sfb]) {
 120          sfbWidth = sfbOffset[sfbGrp+sfb+1] - sfbOffset[sfbGrp+sfb];
 121          /* estimate number of active lines */
 122          avgFormFactorLdData = ((-sfbEnergyLdData[sfbGrp+sfb]>>1) + (CalcLdInt(sfbWidth)>>1))>>1;
 123          peChanData->sfbNLines[sfbGrp+sfb] =
 124            (INT)CalcInvLdData( (sfbFormFactorLdData[sfbGrp+sfb] + formFacScaling) + avgFormFactorLdData);
 125          /* Make sure sfbNLines is never greater than sfbWidth due to unaccuracies (e.g. sfbEnergyLdData[sfbGrp+sfb] = 0x80000000) */
 126          peChanData->sfbNLines[sfbGrp+sfb] = fMin(sfbWidth, peChanData->sfbNLines[sfbGrp+sfb]);
 127       }
 128       else {
 129          peChanData->sfbNLines[sfbGrp+sfb] = 0;
 130       }
 131     }
 132    }
 133 }
 134
 135 /*
 136    formula for one sfb:
 137    pe = n * ld(en/thr),                if ld(en/thr) >= C1
 138    pe = n * (C2 + C3 * ld(en/thr)),    if ld(en/thr) <  C1
 139    n: estimated number of lines in sfb,
 140    ld(x) = log(x)/log(2)
 141
 142    constPart is sfbPe without the threshold part n*ld(thr) or n*C3*ld(thr)
 143 */
 144 void FDKaacEnc_calcSfbPe(PE_CHANNEL_DATA  *RESTRICT peChanData,
 145                const FIXP_DBL   *RESTRICT sfbEnergyLdData,
 146                const FIXP_DBL   *RESTRICT sfbThresholdLdData,
 147                const INT        sfbCnt,
 148                const INT        sfbPerGroup,
 149                const INT        maxSfbPerGroup,
 150                const INT       *isBook,
 151                const INT       *isScale)
 152 {
 153    INT sfbGrp,sfb;
 154    INT nLines;
 155    FIXP_DBL logDataRatio;
 156    INT lastValIs = 0;
 157
 158    peChanData->pe = 0;
 159    peChanData->constPart = 0;
 160    peChanData->nActiveLines = 0;
 161
 162    for(sfbGrp = 0;sfbGrp < sfbCnt;sfbGrp+=sfbPerGroup){
 163     for (sfb=0; sfb<maxSfbPerGroup; sfb++) {
 164       if ((FIXP_DBL)sfbEnergyLdData[sfbGrp+sfb] > (FIXP_DBL)sfbThresholdLdData[sfbGrp+sfb]) {
 165          logDataRatio = (FIXP_DBL)(sfbEnergyLdData[sfbGrp+sfb] - sfbThresholdLdData[sfbGrp+sfb]);
 166          nLines = peChanData->sfbNLines[sfbGrp+sfb];
 167          if (logDataRatio >= C1LdData) {
 168             /* scale sfbPe and sfbConstPart with PE_CONSTPART_SHIFT */
 169             peChanData->sfbPe[sfbGrp+sfb] = fMultDiv2(logDataRatio, (FIXP_DBL)(nLines<<(LD_DATA_SHIFT+PE_CONSTPART_SHIFT+1)));
 170             peChanData->sfbConstPart[sfbGrp+sfb] =
 171                     fMultDiv2(sfbEnergyLdData[sfbGrp+sfb], (FIXP_DBL)(nLines<<(LD_DATA_SHIFT+PE_CONSTPART_SHIFT+1))); ;
 172
 173          }
 174          else {
 175             /* scale sfbPe and sfbConstPart with PE_CONSTPART_SHIFT */
 176             peChanData->sfbPe[sfbGrp+sfb] =
 177                      fMultDiv2(((FIXP_DBL)C2LdData + fMult(C3LdData,logDataRatio)), (FIXP_DBL)(nLines<<(LD_DATA_SHIFT+PE_CONSTPART_SHIFT+1)));
 178
 179             peChanData->sfbConstPart[sfbGrp+sfb] =
 180                      fMultDiv2(((FIXP_DBL)C2LdData + fMult(C3LdData,sfbEnergyLdData[sfbGrp+sfb])),
 181                            (FIXP_DBL)(nLines<<(LD_DATA_SHIFT+PE_CONSTPART_SHIFT+1))) ;
 182
 183             nLines = fMultI(C3LdData, nLines);
 184          }
 185          peChanData->sfbNActiveLines[sfbGrp+sfb] = nLines;
 186       }
 187       else if( isBook[sfbGrp+sfb] ) {
 188         /* provide for cost of scale factor for Intensity */
 189         INT delta = isScale[sfbGrp+sfb] - lastValIs;
 190         lastValIs = isScale[sfbGrp+sfb];
 191         peChanData->sfbPe[sfbGrp+sfb] = FDKaacEnc_bitCountScalefactorDelta(delta)<<PE_CONSTPART_SHIFT;
 192         peChanData->sfbConstPart[sfbGrp+sfb] = 0;
 193         peChanData->sfbNActiveLines[sfbGrp+sfb] = 0;
 194       }
 195       else {
 196          peChanData->sfbPe[sfbGrp+sfb] = 0;
 197          peChanData->sfbConstPart[sfbGrp+sfb] = 0;
 198          peChanData->sfbNActiveLines[sfbGrp+sfb] = 0;
 199       }
 200       /* sum up peChanData values */
 201       peChanData->pe += peChanData->sfbPe[sfbGrp+sfb];
 202       peChanData->constPart += peChanData->sfbConstPart[sfbGrp+sfb];
 203       peChanData->nActiveLines += peChanData->sfbNActiveLines[sfbGrp+sfb];
 204     }
 205    }
 206    /* correct scaled pe and constPart values */
 207    peChanData->pe>>=PE_CONSTPART_SHIFT;
 208    peChanData->constPart>>=PE_CONSTPART_SHIFT;
 209 }