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      1 /* -----------------------------------------------------------------------------
      2 Software License for The Fraunhofer FDK AAC Codec Library for Android
      3 
      4  Copyright  1995 - 2018 Fraunhofer-Gesellschaft zur Frderung der angewandten
      5 Forschung e.V. All rights reserved.
      6 
      7  1.    INTRODUCTION
      8 The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software
      9 that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding
     10 scheme for digital audio. This FDK AAC Codec software is intended to be used on
     11 a wide variety of Android devices.
     12 
     13 AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient
     14 general perceptual audio codecs. AAC-ELD is considered the best-performing
     15 full-bandwidth communications codec by independent studies and is widely
     16 deployed. AAC has been standardized by ISO and IEC as part of the MPEG
     17 specifications.
     18 
     19 Patent licenses for necessary patent claims for the FDK AAC Codec (including
     20 those of Fraunhofer) may be obtained through Via Licensing
     21 (www.vialicensing.com) or through the respective patent owners individually for
     22 the purpose of encoding or decoding bit streams in products that are compliant
     23 with the ISO/IEC MPEG audio standards. Please note that most manufacturers of
     24 Android devices already license these patent claims through Via Licensing or
     25 directly from the patent owners, and therefore FDK AAC Codec software may
     26 already be covered under those patent licenses when it is used for those
     27 licensed purposes only.
     28 
     29 Commercially-licensed AAC software libraries, including floating-point versions
     30 with enhanced sound quality, are also available from Fraunhofer. Users are
     31 encouraged to check the Fraunhofer website for additional applications
     32 information and documentation.
     33 
     34 2.    COPYRIGHT LICENSE
     35 
     36 Redistribution and use in source and binary forms, with or without modification,
     37 are permitted without payment of copyright license fees provided that you
     38 satisfy the following conditions:
     39 
     40 You must retain the complete text of this software license in redistributions of
     41 the FDK AAC Codec or your modifications thereto in source code form.
     42 
     43 You must retain the complete text of this software license in the documentation
     44 and/or other materials provided with redistributions of the FDK AAC Codec or
     45 your modifications thereto in binary form. You must make available free of
     46 charge copies of the complete source code of the FDK AAC Codec and your
     47 modifications thereto to recipients of copies in binary form.
     48 
     49 The name of Fraunhofer may not be used to endorse or promote products derived
     50 from this library without prior written permission.
     51 
     52 You may not charge copyright license fees for anyone to use, copy or distribute
     53 the FDK AAC Codec software or your modifications thereto.
     54 
     55 Your modified versions of the FDK AAC Codec must carry prominent notices stating
     56 that you changed the software and the date of any change. For modified versions
     57 of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec Library for Android"
     58 must be replaced by the term "Third-Party Modified Version of the Fraunhofer FDK
     59 AAC Codec Library for Android."
     60 
     61 3.    NO PATENT LICENSE
     62 
     63 NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without
     64 limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE.
     65 Fraunhofer provides no warranty of patent non-infringement with respect to this
     66 software.
     67 
     68 You may use this FDK AAC Codec software or modifications thereto only for
     69 purposes that are authorized by appropriate patent licenses.
     70 
     71 4.    DISCLAIMER
     72 
     73 This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright
     74 holders and contributors "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES,
     75 including but not limited to the implied warranties of merchantability and
     76 fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
     77 CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary,
     78 or consequential damages, including but not limited to procurement of substitute
     79 goods or services; loss of use, data, or profits, or business interruption,
     80 however caused and on any theory of liability, whether in contract, strict
     81 liability, or tort (including negligence), arising in any way out of the use of
     82 this software, even if advised of the possibility of such damage.
     83 
     84 5.    CONTACT INFORMATION
     85 
     86 Fraunhofer Institute for Integrated Circuits IIS
     87 Attention: Audio and Multimedia Departments - FDK AAC LL
     88 Am Wolfsmantel 33
     89 91058 Erlangen, Germany
     90 
     91 www.iis.fraunhofer.de/amm
     92 amm-info (at) iis.fraunhofer.de
     93 ----------------------------------------------------------------------------- */
     94 
     95 /**************************** AAC encoder library ******************************
     96 
     97    Author(s):   M.Werner
     98 
     99    Description: Pre echo control
    100 
    101 *******************************************************************************/
    102 
    103 #include "pre_echo_control.h"
    104 #include "psy_configuration.h"
    105 
    106 void FDKaacEnc_InitPreEchoControl(FIXP_DBL *RESTRICT pbThresholdNm1,
    107                                   INT *calcPreEcho, INT numPb,
    108                                   FIXP_DBL *RESTRICT sfbPcmQuantThreshold,
    109                                   INT *mdctScalenm1) {
    110   *mdctScalenm1 = PCM_QUANT_THR_SCALE >> 1;
    111 
    112   FDKmemcpy(pbThresholdNm1, sfbPcmQuantThreshold, numPb * sizeof(FIXP_DBL));
    113 
    114   *calcPreEcho = 1;
    115 }
    116 
    117 void FDKaacEnc_PreEchoControl(FIXP_DBL *RESTRICT pbThresholdNm1,
    118                               INT calcPreEcho, INT numPb,
    119                               INT maxAllowedIncreaseFactor,
    120                               FIXP_SGL minRemainingThresholdFactor,
    121                               FIXP_DBL *RESTRICT pbThreshold, INT mdctScale,
    122                               INT *mdctScalenm1) {
    123   int i;
    124   FIXP_DBL tmpThreshold1, tmpThreshold2;
    125   int scaling;
    126 
    127   /* If lastWindowSequence in previous frame was start- or stop-window,
    128      skip preechocontrol calculation */
    129   if (calcPreEcho == 0) {
    130     /* copy thresholds to internal memory */
    131     FDKmemcpy(pbThresholdNm1, pbThreshold, numPb * sizeof(FIXP_DBL));
    132     *mdctScalenm1 = mdctScale;
    133     return;
    134   }
    135 
    136   if (mdctScale > *mdctScalenm1) {
    137     /* if current thresholds are downscaled more than the ones from the last
    138      * block */
    139     scaling = 2 * (mdctScale - *mdctScalenm1);
    140     for (i = 0; i < numPb; i++) {
    141       /* multiplication with return data type fract ist equivalent to int
    142        * multiplication */
    143       FDK_ASSERT(scaling >= 0);
    144       tmpThreshold1 = maxAllowedIncreaseFactor * (pbThresholdNm1[i] >> scaling);
    145       tmpThreshold2 = fMult(minRemainingThresholdFactor, pbThreshold[i]);
    146 
    147       FIXP_DBL tmp = pbThreshold[i];
    148 
    149       /* copy thresholds to internal memory */
    150       pbThresholdNm1[i] = tmp;
    151 
    152       tmp = fixMin(tmp, tmpThreshold1);
    153       pbThreshold[i] = fixMax(tmp, tmpThreshold2);
    154     }
    155   } else {
    156     /* if thresholds of last block are more downscaled than the current ones */
    157     scaling = 2 * (*mdctScalenm1 - mdctScale);
    158     for (i = 0; i < numPb; i++) {
    159       /* multiplication with return data type fract ist equivalent to int
    160        * multiplication */
    161       tmpThreshold1 = (maxAllowedIncreaseFactor >> 1) * pbThresholdNm1[i];
    162       tmpThreshold2 = fMult(minRemainingThresholdFactor, pbThreshold[i]);
    163 
    164       /* copy thresholds to internal memory */
    165       pbThresholdNm1[i] = pbThreshold[i];
    166 
    167       FDK_ASSERT(scaling >= 0);
    168       if ((pbThreshold[i] >> (scaling + 1)) > tmpThreshold1) {
    169         pbThreshold[i] = tmpThreshold1 << (scaling + 1);
    170       }
    171       pbThreshold[i] = fixMax(pbThreshold[i], tmpThreshold2);
    172     }
    173   }
    174 
    175   *mdctScalenm1 = mdctScale;
    176 }
    177