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      1 
      2 /* -----------------------------------------------------------------------------------------------------------
      3 Software License for The Fraunhofer FDK AAC Codec Library for Android
      4 
      5  Copyright  1995 - 2012 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 /******************************** MPEG Audio Encoder **************************
     85 
     86    Initial author:       M.Werner
     87    contents/description: Pre echo control
     88 
     89 ******************************************************************************/
     90 
     91 #include "pre_echo_control.h"
     92 #include "psy_configuration.h"
     93 
     94 void FDKaacEnc_InitPreEchoControl(FIXP_DBL    *RESTRICT pbThresholdNm1,
     95                                   INT         *calcPreEcho,
     96                                   INT          numPb,
     97                                   FIXP_DBL    *RESTRICT sfbPcmQuantThreshold,
     98                                   INT         *mdctScalenm1)
     99 {
    100   *mdctScalenm1 = PCM_QUANT_THR_SCALE>>1;
    101 
    102   FDKmemcpy(pbThresholdNm1, sfbPcmQuantThreshold, numPb*sizeof(FIXP_DBL));
    103 
    104   *calcPreEcho = 1;
    105 }
    106 
    107 
    108 void FDKaacEnc_PreEchoControl(FIXP_DBL   *RESTRICT pbThresholdNm1,
    109                               INT         calcPreEcho,
    110                               INT         numPb,
    111                               INT         maxAllowedIncreaseFactor,
    112                               FIXP_SGL    minRemainingThresholdFactor,
    113                               FIXP_DBL   *RESTRICT pbThreshold,
    114                               INT         mdctScale,
    115                               INT        *mdctScalenm1)
    116 {
    117     int i;
    118     FIXP_DBL tmpThreshold1, tmpThreshold2;
    119     int scaling;
    120 
    121 	/* If lastWindowSequence in previous frame was start- or stop-window,
    122 	   skip preechocontrol calculation */
    123     if (calcPreEcho==0) {
    124       /* copy thresholds to internal memory */
    125       FDKmemcpy(pbThresholdNm1, pbThreshold, numPb*sizeof(FIXP_DBL));
    126       *mdctScalenm1 = mdctScale;
    127       return;
    128     }
    129 
    130     if ( mdctScale > *mdctScalenm1 ) {
    131         /* if current thresholds are downscaled more than the ones from the last block */
    132         scaling = 2*(mdctScale-*mdctScalenm1);
    133         for(i = 0; i < numPb; i++) {
    134 
    135             /* multiplication with return data type fract ist equivalent to int multiplication */
    136             FDK_ASSERT(scaling>=0);
    137             tmpThreshold1 = maxAllowedIncreaseFactor * (pbThresholdNm1[i]>>scaling);
    138             tmpThreshold2 = fMult(minRemainingThresholdFactor, pbThreshold[i]);
    139 
    140 			FIXP_DBL tmp = pbThreshold[i];
    141 
    142             /* copy thresholds to internal memory */
    143             pbThresholdNm1[i] = tmp;
    144 
    145             tmp = fixMin(tmp, tmpThreshold1);
    146             pbThreshold[i] = fixMax(tmp, tmpThreshold2);
    147         }
    148     }
    149     else {
    150         /* if thresholds of last block are more downscaled than the current ones */
    151         scaling = 2*(*mdctScalenm1-mdctScale);
    152         for(i = 0; i < numPb; i++) {
    153 
    154             /* multiplication with return data type fract ist equivalent to int multiplication */
    155             tmpThreshold1 = (maxAllowedIncreaseFactor>>1) * pbThresholdNm1[i];
    156             tmpThreshold2 = fMult(minRemainingThresholdFactor, pbThreshold[i]);
    157 
    158             /* copy thresholds to internal memory */
    159             pbThresholdNm1[i] = pbThreshold[i];
    160 
    161             FDK_ASSERT(scaling>=0);
    162             if((pbThreshold[i]>>(scaling+1)) > tmpThreshold1) {
    163                 pbThreshold[i] = tmpThreshold1<<(scaling+1);
    164             }
    165             pbThreshold[i] = fixMax(pbThreshold[i], tmpThreshold2);
    166         }
    167     }
    168 
    169     *mdctScalenm1 = mdctScale;
    170 }
    171