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+/* -----------------------------------------------------------------------------
+Software License for The Fraunhofer FDK AAC Codec Library for Android
+
+© Copyright  1995 - 2018 Fraunhofer-Gesellschaft zur Förderung der angewandten
+Forschung e.V. All rights reserved.
+
+ 1.    INTRODUCTION
+The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software
+that implements the MPEG Advanced Audio Coding ("AAC") encoding and decoding
+scheme for digital audio. This FDK AAC Codec software is intended to be used on
+a wide variety of Android devices.
+
+AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient
+general perceptual audio codecs. AAC-ELD is considered the best-performing
+full-bandwidth communications codec by independent studies and is widely
+deployed. AAC has been standardized by ISO and IEC as part of the MPEG
+specifications.
+
+Patent licenses for necessary patent claims for the FDK AAC Codec (including
+those of Fraunhofer) may be obtained through Via Licensing
+(www.vialicensing.com) or through the respective patent owners individually for
+the purpose of encoding or decoding bit streams in products that are compliant
+with the ISO/IEC MPEG audio standards. Please note that most manufacturers of
+Android devices already license these patent claims through Via Licensing or
+directly from the patent owners, and therefore FDK AAC Codec software may
+already be covered under those patent licenses when it is used for those
+licensed purposes only.
+
+Commercially-licensed AAC software libraries, including floating-point versions
+with enhanced sound quality, are also available from Fraunhofer. Users are
+encouraged to check the Fraunhofer website for additional applications
+information and documentation.
+
+2.    COPYRIGHT LICENSE
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted without payment of copyright license fees provided that you
+satisfy the following conditions:
+
+You must retain the complete text of this software license in redistributions of
+the FDK AAC Codec or your modifications thereto in source code form.
+
+You must retain the complete text of this software license in the documentation
+and/or other materials provided with redistributions of the FDK AAC Codec or
+your modifications thereto in binary form. You must make available free of
+charge copies of the complete source code of the FDK AAC Codec and your
+modifications thereto to recipients of copies in binary form.
+
+The name of Fraunhofer may not be used to endorse or promote products derived
+from this library without prior written permission.
+
+You may not charge copyright license fees for anyone to use, copy or distribute
+the FDK AAC Codec software or your modifications thereto.
+
+Your modified versions of the FDK AAC Codec must carry prominent notices stating
+that you changed the software and the date of any change. For modified versions
+of the FDK AAC Codec, the term "Fraunhofer FDK AAC Codec Library for Android"
+must be replaced by the term "Third-Party Modified Version of the Fraunhofer FDK
+AAC Codec Library for Android."
+
+3.    NO PATENT LICENSE
+
+NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without
+limitation the patents of Fraunhofer, ARE GRANTED BY THIS SOFTWARE LICENSE.
+Fraunhofer provides no warranty of patent non-infringement with respect to this
+software.
+
+You may use this FDK AAC Codec software or modifications thereto only for
+purposes that are authorized by appropriate patent licenses.
+
+4.    DISCLAIMER
+
+This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright
+holders and contributors "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES,
+including but not limited to the implied warranties of merchantability and
+fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
+CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary,
+or consequential damages, including but not limited to procurement of substitute
+goods or services; loss of use, data, or profits, or business interruption,
+however caused and on any theory of liability, whether in contract, strict
+liability, or tort (including negligence), arising in any way out of the use of
+this software, even if advised of the possibility of such damage.
+
+5.    CONTACT INFORMATION
+
+Fraunhofer Institute for Integrated Circuits IIS
+Attention: Audio and Multimedia Departments - FDK AAC LL
+Am Wolfsmantel 33
+91058 Erlangen, Germany
+
+www.iis.fraunhofer.de/amm
+amm-info@iis.fraunhofer.de
+----------------------------------------------------------------------------- */
+
+/**************************** AAC encoder library ******************************
+
+   Author(s):   M.Werner
+
+   Description: Pre echo control
+
+*******************************************************************************/
+
+#include "pre_echo_control.h"
+#include "psy_configuration.h"
+
+void FDKaacEnc_InitPreEchoControl(FIXP_DBL *RESTRICT pbThresholdNm1,
+                                  INT *calcPreEcho, INT numPb,
+                                  FIXP_DBL *RESTRICT sfbPcmQuantThreshold,
+                                  INT *mdctScalenm1) {
+  *mdctScalenm1 = PCM_QUANT_THR_SCALE >> 1;
+
+  FDKmemcpy(pbThresholdNm1, sfbPcmQuantThreshold, numPb * sizeof(FIXP_DBL));
+
+  *calcPreEcho = 1;
+}
+
+void FDKaacEnc_PreEchoControl(FIXP_DBL *RESTRICT pbThresholdNm1,
+                              INT calcPreEcho, INT numPb,
+                              INT maxAllowedIncreaseFactor,
+                              FIXP_SGL minRemainingThresholdFactor,
+                              FIXP_DBL *RESTRICT pbThreshold, INT mdctScale,
+                              INT *mdctScalenm1) {
+  int i;
+  FIXP_DBL tmpThreshold1, tmpThreshold2;
+  int scaling;
+
+  /* If lastWindowSequence in previous frame was start- or stop-window,
+     skip preechocontrol calculation */
+  if (calcPreEcho == 0) {
+    /* copy thresholds to internal memory */
+    FDKmemcpy(pbThresholdNm1, pbThreshold, numPb * sizeof(FIXP_DBL));
+    *mdctScalenm1 = mdctScale;
+    return;
+  }
+
+  if (mdctScale > *mdctScalenm1) {
+    /* if current thresholds are downscaled more than the ones from the last
+     * block */
+    scaling = 2 * (mdctScale - *mdctScalenm1);
+    for (i = 0; i < numPb; i++) {
+      /* multiplication with return data type fract ist equivalent to int
+       * multiplication */
+      FDK_ASSERT(scaling >= 0);
+      tmpThreshold1 = maxAllowedIncreaseFactor * (pbThresholdNm1[i] >> scaling);
+      tmpThreshold2 = fMult(minRemainingThresholdFactor, pbThreshold[i]);
+
+      FIXP_DBL tmp = pbThreshold[i];
+
+      /* copy thresholds to internal memory */
+      pbThresholdNm1[i] = tmp;
+
+      tmp = fixMin(tmp, tmpThreshold1);
+      pbThreshold[i] = fixMax(tmp, tmpThreshold2);
+    }
+  } else {
+    /* if thresholds of last block are more downscaled than the current ones */
+    scaling = 2 * (*mdctScalenm1 - mdctScale);
+    for (i = 0; i < numPb; i++) {
+      /* multiplication with return data type fract ist equivalent to int
+       * multiplication */
+      tmpThreshold1 = (maxAllowedIncreaseFactor >> 1) * pbThresholdNm1[i];
+      tmpThreshold2 = fMult(minRemainingThresholdFactor, pbThreshold[i]);
+
+      /* copy thresholds to internal memory */
+      pbThresholdNm1[i] = pbThreshold[i];
+
+      FDK_ASSERT(scaling >= 0);
+      if ((pbThreshold[i] >> (scaling + 1)) > tmpThreshold1) {
+        pbThreshold[i] = tmpThreshold1 << (scaling + 1);
+      }
+      pbThreshold[i] = fixMax(pbThreshold[i], tmpThreshold2);
+    }
+  }
+
+  *mdctScalenm1 = mdctScale;
+}