Snapshot 2bda038c163298531d47394bc2c09e1409c5d0db

Change-Id: If584e579464f28b97d50e51fc76ba654a5536c54

1 files changed, 1348 insertions, 0 deletions

diff --git a/libAACenc/src/aacenc_tns.cpp b/libAACenc/src/aacenc_tns.cpp
new file mode 100644
index 0000000..933e4e7
--- /dev/null
+++ b/libAACenc/src/aacenc_tns.cpp
@@ -0,0 +1,1348 @@
+
+/* -----------------------------------------------------------------------------------------------------------
+Software License for The Fraunhofer FDK AAC Codec Library for Android
+
+© Copyright  1995 - 2012 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
+----------------------------------------------------------------------------------------------------------- */
+
+/******************************** MPEG Audio Encoder **************************
+
+   Initial author:       Alex Groeschel
+   contents/description: Temporal noise shaping
+
+******************************************************************************/
+
+#include "aacenc_tns.h"
+#include "psy_const.h"
+#include "psy_configuration.h"
+#include "tns_func.h"
+#include "aacEnc_rom.h"
+#include "aacenc_tns.h"
+
+enum {
+    HIFILT = 0, /* index of higher filter */
+    LOFILT = 1 /* index of lower filter */
+};
+
+
+#define FILTER_DIRECTION 0
+
+static const FIXP_DBL acfWindowLong[12+3+1] = {
+  0x7fffffff,0x7fb80000,0x7ee00000,0x7d780000,0x7b800000,0x78f80000,0x75e00000,0x72380000,
+  0x6e000000,0x69380000,0x63e00000,0x5df80000,0x57800000,0x50780000,0x48e00000,0x40b80000
+};
+
+static const FIXP_DBL acfWindowShort[4+3+1] = {
+  0x7fffffff,0x7e000000,0x78000000,0x6e000000,0x60000000,0x4e000000,0x38000000,0x1e000000
+};
+
+
+typedef struct {
+  INT      filterEnabled[MAX_NUM_OF_FILTERS];
+  INT      threshOn[MAX_NUM_OF_FILTERS];                /* min. prediction gain for using tns TABUL*/
+  INT      filterStartFreq[MAX_NUM_OF_FILTERS];         /* lowest freq for lpc TABUL*/
+  INT      tnsLimitOrder[MAX_NUM_OF_FILTERS];           /* Limit for TNS order TABUL*/
+  INT      tnsFilterDirection[MAX_NUM_OF_FILTERS];      /* Filtering direction, 0=up, 1=down TABUL */
+  INT      acfSplit[MAX_NUM_OF_FILTERS];
+  FIXP_DBL tnsTimeResolution[MAX_NUM_OF_FILTERS];       /* TNS max. time resolution TABUL. Should be fract but MSVC won't compile then */
+  INT      seperateFiltersAllowed;
+
+} TNS_PARAMETER_TABULATED;
+
+
+typedef struct{
+  INT                      bitRateFrom[2];  /* noneSbr=0, useSbr=1 */
+  INT                      bitRateTo[2];    /* noneSbr=0, useSbr=1 */
+  TNS_PARAMETER_TABULATED  paramTab[2];     /* mono=0, stereo=1 */
+
+} TNS_INFO_TAB;
+
+#define TNS_TIMERES_SCALE    (1)
+#define FL2_TIMERES_FIX(a)   ( FL2FXCONST_DBL(a/(float)(1<<TNS_TIMERES_SCALE)) )
+
+static const TNS_INFO_TAB tnsInfoTab[] =
+{
+  {
+    {  16000,  13500},
+    {  32000,  28000},
+    {
+      { {1, 1}, {1437, 1500}, {1400, 600}, {12, 12}, {FILTER_DIRECTION, FILTER_DIRECTION}, {3, 1}, {FL2_TIMERES_FIX(0.4f), FL2_TIMERES_FIX(1.2f)}, 1 },
+      { {1, 1}, {1437, 1500}, {1400, 600}, {12, 12}, {FILTER_DIRECTION, FILTER_DIRECTION}, {3, 1}, {FL2_TIMERES_FIX(0.4f), FL2_TIMERES_FIX(1.2f)}, 1 }
+    }
+  },
+  {
+    {  32001,  28001},
+    {  60000,  52000},
+    {
+      { {1, 1}, {1437, 1500}, {1400, 600}, {12, 10}, {FILTER_DIRECTION, FILTER_DIRECTION}, {3, 1}, {FL2_TIMERES_FIX(0.4f), FL2_TIMERES_FIX(1.0f)}, 1 },
+      { {1, 1}, {1437, 1500}, {1400, 600}, {12, 10}, {FILTER_DIRECTION, FILTER_DIRECTION}, {3, 1}, {FL2_TIMERES_FIX(0.4f), FL2_TIMERES_FIX(1.0f)}, 1 }
+    }
+  },
+  {
+    {  60001,  52001},
+    { 384000, 384000},
+    {
+      { {1, 1}, {1437, 1500}, {1400, 600}, {12,  8}, {FILTER_DIRECTION, FILTER_DIRECTION}, {3, 1}, {FL2_TIMERES_FIX(0.4f), FL2_TIMERES_FIX(1.0f)}, 1 },
+      { {1, 1}, {1437, 1500}, {1400, 600}, {12,  8}, {FILTER_DIRECTION, FILTER_DIRECTION}, {3, 1}, {FL2_TIMERES_FIX(0.4f), FL2_TIMERES_FIX(1.0f)}, 1 }
+    }
+  }
+};
+
+typedef struct {
+  INT   samplingRate;
+  SCHAR maxBands[2]; /* long=0; short=1 */
+
+} TNS_MAX_TAB_ENTRY;
+
+static const TNS_MAX_TAB_ENTRY tnsMaxBandsTab1024[] =
+{
+  { 96000, { 31,  9}},
+  { 88200, { 31,  9}},
+  { 64000, { 34, 10}},
+  { 48000, { 40, 14}},
+  { 44100, { 42, 14}},
+  { 32000, { 51, 14}},
+  { 24000, { 46, 14}},
+  { 22050, { 46, 14}},
+  { 16000, { 42, 14}},
+  { 12000, { 42, 14}},
+  { 11025, { 42, 14}},
+  { 8000,  { 39, 14}}
+};
+
+static const TNS_MAX_TAB_ENTRY tnsMaxBandsTab480[] =
+{
+  { 48000, { 31, -1}},
+  { 44100, { 32, -1}},
+  { 32000, { 37, -1}},
+  { 24000, { 30, -1}},
+  { 22050, { 30, -1}}
+};
+
+static const TNS_MAX_TAB_ENTRY tnsMaxBandsTab512[] =
+{
+  { 48000, { 31, -1}},
+  { 44100, { 32, -1}},
+  { 32000, { 37, -1}},
+  { 24000, { 31, -1}},
+  { 22050, { 31, -1}}
+};
+
+static INT FDKaacEnc_AutoToParcor(
+        FIXP_DBL *RESTRICT input,
+        FIXP_DBL *RESTRICT reflCoeff,
+        const INT numOfCoeff
+        );
+
+static void FDKaacEnc_Parcor2Index(
+        const FIXP_DBL *parcor,
+        INT *RESTRICT index,
+        const INT order,
+        const INT bitsPerCoeff
+        );
+
+static void FDKaacEnc_Index2Parcor(
+        const INT *index,
+        FIXP_DBL *RESTRICT parcor,
+        const INT order,
+        const INT bitsPerCoeff
+        );
+
+static INT FDKaacEnc_ParcorToLpc(
+        const FIXP_DBL *reflCoeff,
+        FIXP_DBL *RESTRICT LpcCoeff,
+        const INT numOfCoeff,
+        FIXP_DBL *RESTRICT workBuffer
+        );
+
+static void FDKaacEnc_AnalysisFilter(
+        FIXP_DBL *RESTRICT signal,
+        const INT numOfLines,
+        const FIXP_DBL *predictorCoeff,
+        const INT order,
+        const INT lpcGainFactor
+        );
+
+static void FDKaacEnc_CalcGaussWindow(
+        FIXP_DBL *win,
+        const int winSize,
+        const INT samplingRate,
+        const INT transformResolution,
+        const FIXP_DBL timeResolution,
+        const INT timeResolution_e
+        );
+
+static const TNS_PARAMETER_TABULATED* FDKaacEnc_GetTnsParam(
+        const INT bitRate,
+        const INT channels,
+        const INT sbrLd
+        )
+{
+  int i;
+  const TNS_PARAMETER_TABULATED *tnsConfigTab = NULL;
+
+  for (i = 0; i < (int) (sizeof(tnsInfoTab)/sizeof(TNS_INFO_TAB)); i++) {
+    if ((bitRate >= tnsInfoTab[i].bitRateFrom[sbrLd?1:0]) &&
+         bitRate <= tnsInfoTab[i].bitRateTo[sbrLd?1:0])
+    {
+      tnsConfigTab = &tnsInfoTab[i].paramTab[(channels==1)?0:1];
+    }
+  }
+
+  return tnsConfigTab;
+}
+
+
+static INT getTnsMaxBands(
+        const INT sampleRate,
+        const INT granuleLength,
+        const INT isShortBlock
+        )
+{
+  int i;
+  INT numBands = -1;
+  const TNS_MAX_TAB_ENTRY *pMaxBandsTab = NULL;
+  int maxBandsTabSize = 0;
+
+  switch (granuleLength) {
+    case 960:
+    case 1024:
+      pMaxBandsTab = tnsMaxBandsTab1024;
+      maxBandsTabSize = sizeof(tnsMaxBandsTab1024)/sizeof(TNS_MAX_TAB_ENTRY);
+      break;
+    case 480:
+      pMaxBandsTab = tnsMaxBandsTab480;
+      maxBandsTabSize = sizeof(tnsMaxBandsTab480)/sizeof(TNS_MAX_TAB_ENTRY);
+      break;
+    case 512:
+      pMaxBandsTab = tnsMaxBandsTab512;
+      maxBandsTabSize = sizeof(tnsMaxBandsTab512)/sizeof(TNS_MAX_TAB_ENTRY);
+      break;
+    default:
+      numBands = -1;
+  }
+
+  if (pMaxBandsTab!=NULL) {
+    for (i=0; i<maxBandsTabSize; i++) {
+      numBands = pMaxBandsTab[i].maxBands[(!isShortBlock)?0:1];
+      if (sampleRate >= pMaxBandsTab[i].samplingRate) {
+        break;
+      }
+    }
+  }
+
+  return numBands;
+}
+
+/***************************************************************************/
+/*!
+  \brief     FDKaacEnc_FreqToBandWithRounding
+
+  Returns index of nearest band border
+
+  \param frequency
+  \param sampling frequency
+  \param total number of bands
+  \param pointer to table of band borders
+
+  \return band border
+****************************************************************************/
+
+INT FDKaacEnc_FreqToBandWithRounding(
+        const INT freq,
+        const INT fs,
+        const INT numOfBands,
+        const INT *bandStartOffset
+        )
+{
+  INT lineNumber, band;
+
+  /*  assert(freq >= 0);  */
+  lineNumber = (freq*bandStartOffset[numOfBands]*4/fs+1)/2;
+
+  /* freq > fs/2 */
+  if (lineNumber >= bandStartOffset[numOfBands])
+    return numOfBands;
+
+  /* find band the line number lies in */
+  for (band=0; band<numOfBands; band++) {
+    if (bandStartOffset[band+1]>lineNumber) break;
+  }
+
+  /* round to nearest band border */
+  if (lineNumber - bandStartOffset[band] >
+      bandStartOffset[band+1] - lineNumber )
+    {
+      band++;
+    }
+
+  return(band);
+}
+
+
+/*****************************************************************************
+
+    functionname: FDKaacEnc_InitTnsConfiguration
+    description:  fill TNS_CONFIG structure with sensible content
+    returns:
+    input:        bitrate, samplerate, number of channels,
+                  blocktype (long or short),
+                  TNS Config struct (modified),
+                  psy config struct,
+                  tns active flag
+    output:
+
+*****************************************************************************/
+AAC_ENCODER_ERROR FDKaacEnc_InitTnsConfiguration(INT bitRate,
+                                                 INT sampleRate,
+                                                 INT channels,
+                                                 INT blockType,
+                                                 INT granuleLength,
+                                                 INT ldSbrPresent,
+                                                 TNS_CONFIG *tC,
+                                                 PSY_CONFIGURATION *pC,
+                                                 INT active,
+                                                 INT useTnsPeak)
+{
+  int i;
+  //float acfTimeRes   = (blockType == SHORT_WINDOW) ? 0.125f : 0.046875f;
+
+  if (channels <= 0)
+    return (AAC_ENCODER_ERROR)1;
+
+  /* initialize TNS filter flag, order, and coefficient resolution (in bits per coeff) */
+  tC->tnsActive      = (active) ? TRUE : FALSE;
+  tC->maxOrder       = (blockType == SHORT_WINDOW) ? 5 : 12;  /* maximum: 7, 20 */
+  if (bitRate < 16000)
+    tC->maxOrder -= 2;
+  tC->coefRes        = (blockType == SHORT_WINDOW) ? 3 : 4;
+
+  /* LPC stop line: highest MDCT line to be coded, but do not go beyond TNS_MAX_BANDS! */
+  tC->lpcStopBand = getTnsMaxBands(sampleRate, granuleLength, (blockType == SHORT_WINDOW) ? 1 : 0);
+
+  if (tC->lpcStopBand < 0) {
+    return (AAC_ENCODER_ERROR)1;
+  }
+
+  tC->lpcStopBand = FDKmin(tC->lpcStopBand, pC->sfbActive);
+  tC->lpcStopLine    = pC->sfbOffset[tC->lpcStopBand];
+
+  switch (granuleLength) {
+    case 960:
+    case 1024:
+      /* TNS start line: skip lower MDCT lines to prevent artifacts due to filter mismatch */
+      tC->lpcStartBand[LOFILT]   = (blockType == SHORT_WINDOW) ? 0 : ((sampleRate < 18783) ? 4 : 8);
+      tC->lpcStartLine[LOFILT]   = pC->sfbOffset[tC->lpcStartBand[LOFILT]];
+
+      i = tC->lpcStopBand;
+      while (pC->sfbOffset[i] > (tC->lpcStartLine[LOFILT] + (tC->lpcStopLine - tC->lpcStartLine[LOFILT]) / 4)) i--;
+      tC->lpcStartBand[HIFILT]   = i;
+      tC->lpcStartLine[HIFILT]   = pC->sfbOffset[i];
+
+      tC->confTab.threshOn[HIFILT] = 1437;
+      tC->confTab.threshOn[LOFILT] = 1500;
+
+      tC->confTab.tnsLimitOrder[HIFILT] = tC->maxOrder;
+      tC->confTab.tnsLimitOrder[LOFILT] = tC->maxOrder - 7;
+
+      tC->confTab.tnsFilterDirection[HIFILT] = FILTER_DIRECTION;
+      tC->confTab.tnsFilterDirection[LOFILT] = FILTER_DIRECTION;
+
+      tC->confTab.acfSplit[HIFILT] = -1;  /* signal Merged4to2QuartersAutoCorrelation in FDKaacEnc_MergedAutoCorrelation*/
+      tC->confTab.acfSplit[LOFILT] = -1;  /* signal Merged4to2QuartersAutoCorrelation in FDKaacEnc_MergedAutoCorrelation */
+
+      tC->confTab.filterEnabled[HIFILT] = 1;
+      tC->confTab.filterEnabled[LOFILT] = 1;
+      tC->confTab.seperateFiltersAllowed = 1;
+
+      /* compute autocorrelation window based on maximum filter order for given block type */
+      /* for (i = 0; i <= tC->maxOrder + 3; i++) {
+           float acfWinTemp = acfTimeRes * i;
+           acfWindow[i] = FL2FXCONST_DBL(1.0f - acfWinTemp * acfWinTemp);
+         }
+      */
+      if (blockType == SHORT_WINDOW) {
+        FDKmemcpy(tC->acfWindow[HIFILT], acfWindowShort, FDKmin(sizeof(acfWindowShort), sizeof(tC->acfWindow[HIFILT])));
+        FDKmemcpy(tC->acfWindow[LOFILT], acfWindowShort, FDKmin(sizeof(acfWindowShort), sizeof(tC->acfWindow[HIFILT])));
+      }
+      else {
+        FDKmemcpy(tC->acfWindow[HIFILT], acfWindowLong, FDKmin(sizeof(acfWindowLong), sizeof(tC->acfWindow[HIFILT])));
+        FDKmemcpy(tC->acfWindow[LOFILT], acfWindowLong, FDKmin(sizeof(acfWindowLong), sizeof(tC->acfWindow[HIFILT])));
+      }
+      break;
+    case 480:
+    case 512:
+      {
+        const TNS_PARAMETER_TABULATED* pCfg = FDKaacEnc_GetTnsParam(bitRate, channels, ldSbrPresent);
+
+        if ( pCfg != NULL ) {
+          tC->lpcStartBand[HIFILT]         = FDKaacEnc_FreqToBandWithRounding(pCfg->filterStartFreq[HIFILT], sampleRate, pC->sfbCnt, pC->sfbOffset);
+          tC->lpcStartLine[HIFILT]         = pC->sfbOffset[tC->lpcStartBand[HIFILT]];
+          tC->lpcStartBand[LOFILT]         = FDKaacEnc_FreqToBandWithRounding(pCfg->filterStartFreq[LOFILT], sampleRate, pC->sfbCnt, pC->sfbOffset);
+          tC->lpcStartLine[LOFILT]         = pC->sfbOffset[tC->lpcStartBand[LOFILT]];
+
+          tC->confTab.threshOn[HIFILT] = pCfg->threshOn[HIFILT];
+          tC->confTab.threshOn[LOFILT] = pCfg->threshOn[LOFILT];
+
+          tC->confTab.tnsLimitOrder[HIFILT] = pCfg->tnsLimitOrder[HIFILT];
+          tC->confTab.tnsLimitOrder[LOFILT] = pCfg->tnsLimitOrder[LOFILT];
+
+          tC->confTab.tnsFilterDirection[HIFILT] = pCfg->tnsFilterDirection[HIFILT];
+          tC->confTab.tnsFilterDirection[LOFILT] = pCfg->tnsFilterDirection[LOFILT];
+
+          tC->confTab.acfSplit[HIFILT] = pCfg->acfSplit[HIFILT];
+          tC->confTab.acfSplit[LOFILT] = pCfg->acfSplit[LOFILT];
+
+          tC->confTab.filterEnabled[HIFILT] = pCfg->filterEnabled[HIFILT];
+          tC->confTab.filterEnabled[LOFILT] = pCfg->filterEnabled[LOFILT];
+          tC->confTab.seperateFiltersAllowed = pCfg->seperateFiltersAllowed;
+
+          FDKaacEnc_CalcGaussWindow(tC->acfWindow[HIFILT], tC->maxOrder+1, sampleRate, granuleLength, pCfg->tnsTimeResolution[HIFILT], TNS_TIMERES_SCALE);
+          FDKaacEnc_CalcGaussWindow(tC->acfWindow[LOFILT], tC->maxOrder+1, sampleRate, granuleLength, pCfg->tnsTimeResolution[LOFILT], TNS_TIMERES_SCALE);
+        }
+        else {
+          tC->tnsActive = FALSE; /* no configuration available, disable tns tool */
+        }
+      }
+      break;
+    default:
+      tC->tnsActive = FALSE; /* no configuration available, disable tns tool */
+  }
+
+  return AAC_ENC_OK;
+
+}
+
+/***************************************************************************/
+/*!
+  \brief     FDKaacEnc_ScaleUpSpectrum
+
+  Scales up spectrum lines in a given frequency section
+
+  \param scaled spectrum
+  \param original spectrum
+  \param frequency line to start scaling
+  \param frequency line to enc scaling
+
+  \return scale factor
+
+****************************************************************************/
+static inline INT FDKaacEnc_ScaleUpSpectrum(
+        FIXP_DBL                 *dest,
+        const FIXP_DBL           *src,
+        const INT                 startLine,
+        const INT                 stopLine
+        )
+{
+    INT i, scale;
+
+    FIXP_DBL maxVal = FL2FXCONST_DBL(0.f);
+
+    /* Get highest value in given spectrum */
+    for (i=startLine; i<stopLine; i++) {
+      maxVal = fixMax(maxVal,fixp_abs(src[i]));
+    }
+    scale = CountLeadingBits(maxVal);
+
+    /* Scale spectrum according to highest value */
+    for (i=startLine; i<stopLine; i++) {
+      dest[i] = src[i]<<scale;
+    }
+
+    return scale;
+}
+
+/***************************************************************************/
+/*!
+  \brief     FDKaacEnc_CalcAutoCorrValue
+
+  Calculate autocorellation value for one lag
+
+  \param pointer to spectrum
+  \param start line
+  \param stop line
+  \param lag to be calculated
+  \param scaling of the lag
+
+****************************************************************************/
+static inline FIXP_DBL FDKaacEnc_CalcAutoCorrValue(
+        const FIXP_DBL           *spectrum,
+        const INT                 startLine,
+        const INT                 stopLine,
+        const INT                 lag,
+        const INT                 scale
+        )
+{
+    int i;
+    FIXP_DBL result = FL2FXCONST_DBL(0.f);
+
+    if (lag==0) {
+      for (i=startLine; i<stopLine; i++) {
+        result += (fPow2(spectrum[i])>>scale);
+      }
+    }
+    else {
+      for (i=startLine; i<(stopLine-lag); i++) {
+        result += (fMult(spectrum[i], spectrum[i+lag])>>scale);
+      }
+    }
+
+    return result;
+}
+
+/***************************************************************************/
+/*!
+  \brief     FDKaacEnc_AutoCorrNormFac
+
+  Autocorrelation function for 1st and 2nd half of the spectrum
+
+  \param pointer to spectrum
+  \param pointer to autocorrelation window
+  \param filter start line
+
+****************************************************************************/
+static inline FIXP_DBL FDKaacEnc_AutoCorrNormFac(
+        const FIXP_DBL            value,
+        const INT                 scale,
+        INT                      *sc
+        )
+{
+    #define HLM_MIN_NRG 0.0000000037252902984619140625f /* 2^-28 */
+    #define MAX_INV_NRGFAC (1.f/HLM_MIN_NRG)
+
+    FIXP_DBL retValue;
+    FIXP_DBL A, B;
+
+    if (scale>=0) {
+      A = value;
+      B = FL2FXCONST_DBL(HLM_MIN_NRG)>>fixMin(DFRACT_BITS-1,scale);
+    }
+    else {
+      A = value>>fixMin(DFRACT_BITS-1,(-scale));
+      B = FL2FXCONST_DBL(HLM_MIN_NRG);
+    }
+
+    if (A > B) {
+      int shift = 0;
+      FIXP_DBL tmp = invSqrtNorm2(value,&shift);
+
+      retValue = fMult(tmp,tmp);
+      *sc += (2*shift);
+    }
+    else {
+      /* MAX_INV_NRGFAC*FDKpow(2,-28) = 1/2^-28 * 2^-28 = 1.0 */
+      retValue = /*FL2FXCONST_DBL(MAX_INV_NRGFAC*FDKpow(2,-28))*/ (FIXP_DBL)MAXVAL_DBL;
+      *sc += scale+28;
+    }
+
+    return retValue;
+}
+
+static void FDKaacEnc_MergedAutoCorrelation(
+        const FIXP_DBL           *spectrum,
+        const FIXP_DBL            acfWindow[MAX_NUM_OF_FILTERS][TNS_MAX_ORDER+3+1],
+        const INT                 lpcStartLine[MAX_NUM_OF_FILTERS],
+        const INT                 lpcStopLine,
+        const INT                 maxOrder,
+        const INT                 acfSplit[MAX_NUM_OF_FILTERS],
+        FIXP_DBL                 *_rxx1,
+        FIXP_DBL                 *_rxx2
+        )
+{
+    int i, idx0, idx1, idx2, idx3, idx4, lag;
+    FIXP_DBL rxx1_0, rxx2_0, rxx3_0, rxx4_0;
+
+    /* buffer for temporal spectrum */
+    C_ALLOC_SCRATCH_START(pSpectrum, FIXP_DBL, (1024));
+
+    /* pre-initialization output */
+    FDKmemclear(&_rxx1[0], sizeof(FIXP_DBL)*(maxOrder+1));
+    FDKmemclear(&_rxx2[0], sizeof(FIXP_DBL)*(maxOrder+1));
+
+    /* MDCT line indices separating the 1st, 2nd, 3rd, and 4th analysis quarters */
+    if ( (acfSplit[LOFILT]==-1) || (acfSplit[HIFILT]==-1) ) {
+      /* autocorrelation function for 1st, 2nd, 3rd, and 4th quarter of the spectrum */
+      idx0 = lpcStartLine[LOFILT];
+      i    = lpcStopLine - lpcStartLine[LOFILT];
+      idx1 = idx0 + i / 4;
+      idx2 = idx0 + i / 2;
+      idx3 = idx0 + i * 3 / 4;
+      idx4 = lpcStopLine;
+    }
+    else {
+      FDK_ASSERT(acfSplit[LOFILT]==1);
+      FDK_ASSERT(acfSplit[HIFILT]==3);
+      i    = (lpcStopLine - lpcStartLine[HIFILT]) / 3;
+      idx0 = lpcStartLine[LOFILT];
+      idx1 = lpcStartLine[HIFILT];
+      idx2 = idx1 + i;
+      idx3 = idx2 + i;
+      idx4 = lpcStopLine;
+    }
+
+    /* copy spectrum to temporal buffer and scale up as much as possible */
+    INT sc1 = FDKaacEnc_ScaleUpSpectrum(pSpectrum, spectrum, idx0, idx1);
+    INT sc2 = FDKaacEnc_ScaleUpSpectrum(pSpectrum, spectrum, idx1, idx2);
+    INT sc3 = FDKaacEnc_ScaleUpSpectrum(pSpectrum, spectrum, idx2, idx3);
+    INT sc4 = FDKaacEnc_ScaleUpSpectrum(pSpectrum, spectrum, idx3, idx4);
+
+    /* get scaling values for summation */
+    INT nsc1, nsc2, nsc3, nsc4;
+    for (nsc1=1; (1<<nsc1)<(idx1-idx0); nsc1++);
+    for (nsc2=1; (1<<nsc2)<(idx2-idx1); nsc2++);
+    for (nsc3=1; (1<<nsc3)<(idx3-idx2); nsc3++);
+    for (nsc4=1; (1<<nsc4)<(idx4-idx3); nsc4++);
+
+    /* compute autocorrelation value at lag zero, i. e. energy, for each quarter */
+    rxx1_0 = FDKaacEnc_CalcAutoCorrValue(pSpectrum, idx0, idx1, 0, nsc1);
+    rxx2_0 = FDKaacEnc_CalcAutoCorrValue(pSpectrum, idx1, idx2, 0, nsc2);
+    rxx3_0 = FDKaacEnc_CalcAutoCorrValue(pSpectrum, idx2, idx3, 0, nsc3);
+    rxx4_0 = FDKaacEnc_CalcAutoCorrValue(pSpectrum, idx3, idx4, 0, nsc4);
+
+    /* compute energy normalization factors, i. e. 1/energy (saves some divisions) */
+    if (rxx1_0 != FL2FXCONST_DBL(0.f))
+    {
+        INT sc_fac1 = -1;
+        FIXP_DBL fac1 = FDKaacEnc_AutoCorrNormFac(rxx1_0, ((-2*sc1)+nsc1), &sc_fac1);
+        _rxx1[0] = scaleValue(fMult(rxx1_0,fac1),sc_fac1);
+
+        for (lag = 1; lag <= maxOrder; lag++) {
+          /* compute energy-normalized and windowed autocorrelation values at this lag */
+          if ((3 * lag) <= maxOrder + 3) {
+              FIXP_DBL x1 = FDKaacEnc_CalcAutoCorrValue(pSpectrum, idx0, idx1, lag, nsc1);
+              _rxx1[lag] = fMult(scaleValue(fMult(x1,fac1),sc_fac1), acfWindow[LOFILT][3*lag]);
+          }
+        }
+    }
+
+    /* auto corr over upper 3/4 of spectrum */
+    if ( !((rxx2_0 == FL2FXCONST_DBL(0.f)) && (rxx3_0 == FL2FXCONST_DBL(0.f)) && (rxx4_0 == FL2FXCONST_DBL(0.f))) )
+    {
+        FIXP_DBL fac2, fac3, fac4;
+        fac2 = fac3 = fac4 = FL2FXCONST_DBL(0.f);
+        INT sc_fac2, sc_fac3, sc_fac4;
+        sc_fac2 = sc_fac3 = sc_fac4 = 0;
+
+        if (rxx2_0!=FL2FXCONST_DBL(0.f)) {
+          fac2 = FDKaacEnc_AutoCorrNormFac(rxx2_0, ((-2*sc2)+nsc2), &sc_fac2);
+          sc_fac2 -= 2;
+        }
+        if (rxx3_0!=FL2FXCONST_DBL(0.f)) {
+          fac3 = FDKaacEnc_AutoCorrNormFac(rxx3_0, ((-2*sc3)+nsc3), &sc_fac3);
+          sc_fac3 -= 2;
+        }
+        if (rxx4_0!=FL2FXCONST_DBL(0.f)) {
+          fac4 = FDKaacEnc_AutoCorrNormFac(rxx4_0, ((-2*sc4)+nsc4), &sc_fac4);
+          sc_fac4 -= 2;
+        }
+
+        _rxx2[0] = scaleValue(fMult(rxx2_0,fac2),sc_fac2) +
+                   scaleValue(fMult(rxx3_0,fac3),sc_fac3) +
+                   scaleValue(fMult(rxx4_0,fac4),sc_fac4);
+
+        for (lag = 1; lag <= maxOrder; lag++) {
+          /* merge quarters 2, 3, 4 into one autocorrelation; quarter 1 stays separate */
+          FIXP_DBL x2 = scaleValue(fMult(FDKaacEnc_CalcAutoCorrValue(pSpectrum, idx1, idx2, lag, nsc2), fac2),sc_fac2) +
+                        scaleValue(fMult(FDKaacEnc_CalcAutoCorrValue(pSpectrum, idx2, idx3, lag, nsc3), fac3),sc_fac3) +
+                        scaleValue(fMult(FDKaacEnc_CalcAutoCorrValue(pSpectrum, idx3, idx4, lag, nsc4), fac4),sc_fac4);
+
+          _rxx2[lag] = fMult(x2, acfWindow[HIFILT][lag]);
+        }
+    }
+
+    C_ALLOC_SCRATCH_END(pSpectrum, FIXP_DBL, (1024));
+}
+
+
+/*****************************************************************************
+    functionname: FDKaacEnc_TnsDetect
+    description:  do decision, if TNS shall be used or not
+    returns:
+    input:        tns data structure (modified),
+                  tns config structure,
+                  scalefactor size and table,
+                  spectrum,
+                  subblock num, blocktype,
+                  sfb-wise energy.
+
+*****************************************************************************/
+INT FDKaacEnc_TnsDetect(
+              TNS_DATA *tnsData,
+              const TNS_CONFIG *tC,
+              TNS_INFO* tnsInfo,
+              INT sfbCnt,
+              FIXP_DBL *spectrum,
+              INT subBlockNumber,
+              INT blockType
+              )
+{
+  /* autocorrelation function for 1st, 2nd, 3rd, and 4th quarter of the spectrum. */
+  FIXP_DBL rxx1[TNS_MAX_ORDER+1]; /* higher part */
+  FIXP_DBL rxx2[TNS_MAX_ORDER+1]; /* lower part */
+  FIXP_DBL parcor_tmp[TNS_MAX_ORDER];
+
+  int i;
+
+  TNS_SUBBLOCK_INFO *tsbi = (blockType == SHORT_WINDOW)
+    ? &tnsData->dataRaw.Short.subBlockInfo[subBlockNumber]
+    : &tnsData->dataRaw.Long.subBlockInfo;
+
+  tnsData->filtersMerged  = FALSE;
+  tsbi->tnsActive         = FALSE;
+  tsbi->predictionGain    = 1000;
+  tnsInfo->numOfFilters[subBlockNumber] = 0;
+  tnsInfo->coefRes[subBlockNumber]      = tC->coefRes;
+  for (i = 0; i < tC->maxOrder; i++) {
+    tnsInfo->coef[subBlockNumber][HIFILT][i] = tnsInfo->coef[subBlockNumber][LOFILT][i] = 0;
+  }
+
+  tnsInfo->length[subBlockNumber][HIFILT] = tnsInfo->length[subBlockNumber][LOFILT] = 0;
+  tnsInfo->order [subBlockNumber][HIFILT] = tnsInfo->order [subBlockNumber][LOFILT] = 0;
+
+  if ( (tC->tnsActive) && (tC->maxOrder>0) )
+  {
+    int sumSqrCoef;
+
+    FDKaacEnc_MergedAutoCorrelation(
+          spectrum,
+          tC->acfWindow,
+          tC->lpcStartLine,
+          tC->lpcStopLine,
+          tC->maxOrder,
+          tC->confTab.acfSplit,
+          rxx1,
+          rxx2);
+
+    /* compute higher TNS filter in lattice (ParCor) form with LeRoux-Gueguen algorithm */
+    tsbi->predictionGain = FDKaacEnc_AutoToParcor(rxx2, parcor_tmp, tC->confTab.tnsLimitOrder[HIFILT]);
+
+    /* non-linear quantization of TNS lattice coefficients with given resolution */
+    FDKaacEnc_Parcor2Index(
+            parcor_tmp,
+            tnsInfo->coef[subBlockNumber][HIFILT],
+            tC->confTab.tnsLimitOrder[HIFILT],
+            tC->coefRes);
+
+    /* reduce filter order by truncating trailing zeros, compute sum(abs(coefs)) */
+    for (i = tC->confTab.tnsLimitOrder[HIFILT] - 1; i >= 0; i--) {
+      if (tnsInfo->coef[subBlockNumber][HIFILT][i] != 0) {
+        break;
+      }
+    }
+
+    tnsInfo->order[subBlockNumber][HIFILT] = i + 1;
+
+    sumSqrCoef = 0;
+    for (; i >= 0; i--) {
+      sumSqrCoef += tnsInfo->coef[subBlockNumber][HIFILT][i] * tnsInfo->coef[subBlockNumber][HIFILT][i];
+    }
+
+    tnsInfo->direction[subBlockNumber][HIFILT] = tC->confTab.tnsFilterDirection[HIFILT];
+    tnsInfo->length[subBlockNumber][HIFILT] = sfbCnt - tC->lpcStartBand[HIFILT];
+
+    /* disable TNS if predictionGain is less than 3dB or sumSqrCoef is too small */
+    if ((tsbi->predictionGain > tC->confTab.threshOn[HIFILT]) || (sumSqrCoef > (tC->confTab.tnsLimitOrder[HIFILT]/2 + 2)))
+    {
+      tsbi->tnsActive = TRUE;
+      tnsInfo->numOfFilters[subBlockNumber]++;
+
+      /* compute second filter for lower quarter; only allowed for long windows! */
+      if ( (blockType != SHORT_WINDOW) &&
+           (tC->confTab.filterEnabled[LOFILT]) && (tC->confTab.seperateFiltersAllowed) )
+      {
+        /* compute second filter for lower frequencies */
+
+        /* compute TNS filter in lattice (ParCor) form with LeRoux-Gueguen algorithm */
+        INT predGain = FDKaacEnc_AutoToParcor(rxx1, parcor_tmp, tC->confTab.tnsLimitOrder[LOFILT]);
+
+        /* non-linear quantization of TNS lattice coefficients with given resolution */
+        FDKaacEnc_Parcor2Index(
+                parcor_tmp,
+                tnsInfo->coef[subBlockNumber][LOFILT],
+                tC->confTab.tnsLimitOrder[LOFILT],
+                tC->coefRes);
+
+        /* reduce filter order by truncating trailing zeros, compute sum(abs(coefs)) */
+        for (i = tC->confTab.tnsLimitOrder[LOFILT] - 1; i >= 0; i--) {
+          if (tnsInfo->coef[subBlockNumber][LOFILT][i] != 0) {
+            break;
+          }
+        }
+        tnsInfo->order[subBlockNumber][LOFILT] = i + 1;
+
+        sumSqrCoef = 0;
+        for (; i >= 0; i--) {
+          sumSqrCoef += tnsInfo->coef[subBlockNumber][LOFILT][i] * tnsInfo->coef[subBlockNumber][LOFILT][i];
+        }
+
+        tnsInfo->direction[subBlockNumber][LOFILT] = tC->confTab.tnsFilterDirection[LOFILT];
+        tnsInfo->length[subBlockNumber][LOFILT] = tC->lpcStartBand[HIFILT] - tC->lpcStartBand[LOFILT];
+
+        /* filter lower quarter if gain is high enough, but not if it's too high */
+        if ( ( (predGain > tC->confTab.threshOn[LOFILT]) && (predGain < (16000 * tC->confTab.tnsLimitOrder[LOFILT])) )
+          || ( (sumSqrCoef > 9)  && (sumSqrCoef < 22 * tC->confTab.tnsLimitOrder[LOFILT]) ) )
+        {
+          /* compare lower to upper filter; if they are very similar, merge them */
+          sumSqrCoef = 0;
+          for (i = 0; i < tC->confTab.tnsLimitOrder[LOFILT]; i++) {
+            sumSqrCoef += FDKabs(tnsInfo->coef[subBlockNumber][HIFILT][i] - tnsInfo->coef[subBlockNumber][LOFILT][i]);
+          }
+          if ( (sumSqrCoef < 2) &&
+               (tnsInfo->direction[subBlockNumber][LOFILT] == tnsInfo->direction[subBlockNumber][HIFILT]) )
+          {
+            tnsData->filtersMerged = TRUE;
+            tnsInfo->length[subBlockNumber][HIFILT] = sfbCnt - tC->lpcStartBand[LOFILT];
+            for (; i < tnsInfo->order[subBlockNumber][HIFILT]; i++) {
+              if (FDKabs(tnsInfo->coef[subBlockNumber][HIFILT][i]) > 1) {
+                break;
+              }
+            }
+            for (i--; i >= 0; i--) {
+              if (tnsInfo->coef[subBlockNumber][HIFILT][i] != 0) {
+                break;
+              }
+            }
+            if (i < tnsInfo->order[subBlockNumber][HIFILT]) {
+              tnsInfo->order[subBlockNumber][HIFILT] = i + 1;
+            }
+          }
+          else {
+            tnsInfo->numOfFilters[subBlockNumber]++;
+          }
+        } /* filter lower part */
+      } /* second filter allowed  */
+    } /* if predictionGain > 1437 ... */
+  } /* maxOrder > 0 && tnsActive */
+
+  return 0;
+
+}
+
+
+/***************************************************************************/
+/*!
+  \brief     FDKaacLdEnc_TnsSync
+
+  synchronize TNS parameters when TNS gain difference small (relative)
+
+  \param pointer to TNS data structure (destination)
+  \param pointer to TNS data structure (source)
+  \param pointer to TNS config structure
+  \param number of sub-block
+  \param block type
+
+  \return void
+****************************************************************************/
+void FDKaacEnc_TnsSync(
+             TNS_DATA *tnsDataDest,
+             const TNS_DATA *tnsDataSrc,
+             TNS_INFO *tnsInfoDest,
+             TNS_INFO *tnsInfoSrc,
+             const INT blockTypeDest,
+             const INT blockTypeSrc,
+             const TNS_CONFIG *tC
+             )
+{
+  int i, w, absDiff, nWindows;
+  TNS_SUBBLOCK_INFO *sbInfoDest;
+  const TNS_SUBBLOCK_INFO *sbInfoSrc;
+
+  /* if one channel contains short blocks and the other not, do not synchronize */
+  if ( (blockTypeSrc == SHORT_WINDOW && blockTypeDest != SHORT_WINDOW) ||
+       (blockTypeDest == SHORT_WINDOW && blockTypeSrc != SHORT_WINDOW) )
+  {
+    return;
+  }
+
+  if (blockTypeDest != SHORT_WINDOW) {
+    sbInfoDest = &tnsDataDest->dataRaw.Long.subBlockInfo;
+    sbInfoSrc  = &tnsDataSrc->dataRaw.Long.subBlockInfo;
+    nWindows   = 1;
+  } else {
+    sbInfoDest = &tnsDataDest->dataRaw.Short.subBlockInfo[0];
+    sbInfoSrc  = &tnsDataSrc->dataRaw.Short.subBlockInfo[0];
+    nWindows   = 8;
+  }
+
+  for (w=0; w<nWindows; w++) {
+      const TNS_SUBBLOCK_INFO *pSbInfoSrcW  = sbInfoSrc  + w;
+      TNS_SUBBLOCK_INFO       *pSbInfoDestW = sbInfoDest + w;
+      INT doSync = 1, absDiffSum = 0;
+
+      /* if TNS is active in at least one channel, check if ParCor coefficients of higher filter are similar */
+      if (pSbInfoDestW->tnsActive || pSbInfoSrcW->tnsActive) {
+        for (i = 0; i < tC->maxOrder; i++) {
+          absDiff = FDKabs(tnsInfoDest->coef[w][HIFILT][i] - tnsInfoSrc->coef[w][HIFILT][i]);
+          absDiffSum += absDiff;
+          /* if coefficients diverge too much between channels, do not synchronize */
+          if ((absDiff > 1) || (absDiffSum > 2)) {
+            doSync = 0;
+            break;
+          }
+        }
+
+        if (doSync) {
+            /* if no significant difference was detected, synchronize coefficient sets */
+            if (pSbInfoSrcW->tnsActive) {
+              /* no dest filter, or more dest than source filters: use one dest filter */
+              if ((!pSbInfoDestW->tnsActive) ||
+                  ((pSbInfoDestW->tnsActive) && (tnsInfoDest->numOfFilters[w] > tnsInfoSrc->numOfFilters[w])))
+              {
+                pSbInfoDestW->tnsActive = tnsInfoDest->numOfFilters[w] = 1;
+              }
+              tnsDataDest->filtersMerged = tnsDataSrc->filtersMerged;
+              tnsInfoDest->order       [w][HIFILT] = tnsInfoSrc->order       [w][HIFILT];
+              tnsInfoDest->length      [w][HIFILT] = tnsInfoSrc->length      [w][HIFILT];
+              tnsInfoDest->direction   [w][HIFILT] = tnsInfoSrc->direction   [w][HIFILT];
+              tnsInfoDest->coefCompress[w][HIFILT] = tnsInfoSrc->coefCompress[w][HIFILT];
+
+              for (i = 0; i < tC->maxOrder; i++) {
+                tnsInfoDest->coef[w][HIFILT][i] = tnsInfoSrc->coef[w][HIFILT][i];
+              }
+            }
+            else
+              pSbInfoDestW->tnsActive = tnsInfoDest->numOfFilters[w] = 0;
+            }
+        }
+
+    }
+}
+
+/***************************************************************************/
+/*!
+  \brief     FDKaacEnc_TnsEncode
+
+  perform TNS encoding
+
+  \param pointer to TNS info structure
+  \param pointer to TNS data structure
+  \param number of sfbs
+  \param pointer to TNS config structure
+  \param low-pass line
+  \param pointer to spectrum
+  \param number of sub-block
+  \param block type
+
+  \return ERROR STATUS
+****************************************************************************/
+INT FDKaacEnc_TnsEncode(
+        TNS_INFO* tnsInfo,
+        TNS_DATA* tnsData,
+        const INT numOfSfb,
+        const TNS_CONFIG *tC,
+        const INT lowPassLine,
+        FIXP_DBL* spectrum,
+        const INT subBlockNumber,
+        const INT blockType
+        )
+{
+    INT i, startLine, stopLine;
+
+    if ( ( (blockType == SHORT_WINDOW) && (!tnsData->dataRaw.Short.subBlockInfo[subBlockNumber].tnsActive) )
+      || ( (blockType != SHORT_WINDOW) && (!tnsData->dataRaw.Long.subBlockInfo.tnsActive) ) )
+    {
+      return 1;
+    }
+
+    startLine = (tnsData->filtersMerged) ? tC->lpcStartLine[LOFILT] : tC->lpcStartLine[HIFILT];
+    stopLine  = tC->lpcStopLine;
+
+    for (i=0; i<tnsInfo->numOfFilters[subBlockNumber]; i++) {
+
+        INT lpcGainFactor;
+        FIXP_DBL LpcCoeff[TNS_MAX_ORDER];
+        FIXP_DBL workBuffer[TNS_MAX_ORDER];
+        FIXP_DBL parcor_tmp[TNS_MAX_ORDER];
+
+        FDKaacEnc_Index2Parcor(
+                tnsInfo->coef[subBlockNumber][i],
+                parcor_tmp,
+                tnsInfo->order[subBlockNumber][i],
+                tC->coefRes);
+
+        lpcGainFactor = FDKaacEnc_ParcorToLpc(
+                parcor_tmp,
+                LpcCoeff,
+                tnsInfo->order[subBlockNumber][i],
+                workBuffer);
+
+        FDKaacEnc_AnalysisFilter(
+                &spectrum[startLine],
+                stopLine - startLine,
+                LpcCoeff,
+                tnsInfo->order[subBlockNumber][i],
+                lpcGainFactor);
+
+        /* update for second filter */
+        startLine = tC->lpcStartLine[LOFILT];
+        stopLine  = tC->lpcStartLine[HIFILT];
+    }
+
+    return(0);
+
+}
+
+static void FDKaacEnc_CalcGaussWindow(
+        FIXP_DBL *win,
+        const int winSize,
+        const INT samplingRate,
+        const INT transformResolution,
+        const FIXP_DBL timeResolution,
+        const INT timeResolution_e
+        )
+{
+  #define PI_SCALE         (2)
+  #define PI_FIX           FL2FXCONST_DBL(3.1416f/(float)(1<<PI_SCALE))
+
+  #define EULER_SCALE      (2)
+  #define EULER_FIX        FL2FXCONST_DBL(2.7183/(float)(1<<EULER_SCALE))
+
+  #define COEFF_LOOP_SCALE (4)
+
+  INT i, e1, e2, gaussExp_e;
+  FIXP_DBL gaussExp_m;
+
+  /* calc. window exponent from time resolution:
+   *
+   *   gaussExp = PI * samplingRate * 0.001f * timeResolution / transformResolution;
+   *   gaussExp = -0.5f * gaussExp * gaussExp;
+   */
+  gaussExp_m = fMultNorm(timeResolution, fMult(PI_FIX, fDivNorm( (FIXP_DBL)(samplingRate), (FIXP_DBL)(LONG)(transformResolution*1000.f), &e1)), &e2);
+  gaussExp_m = -fPow2Div2(gaussExp_m);
+  gaussExp_e = 2*(e1+e2+timeResolution_e+PI_SCALE);
+
+  FDK_ASSERT( winSize < (1<<COEFF_LOOP_SCALE) );
+
+  /* calc. window coefficients
+   *   win[i] = (float)exp( gaussExp * (i+0.5) * (i+0.5) );
+   */
+  for( i=0; i<winSize; i++) {
+
+    win[i] = fPow(
+            EULER_FIX,
+            EULER_SCALE,
+            fMult(gaussExp_m, fPow2((i*FL2FXCONST_DBL(1.f/(float)(1<<COEFF_LOOP_SCALE)) + FL2FXCONST_DBL(.5f/(float)(1<<COEFF_LOOP_SCALE))))),
+            gaussExp_e + 2*COEFF_LOOP_SCALE,
+           &e1);
+
+    win[i] = scaleValue(win[i], e1);
+  }
+}
+
+
+/***************************************************************************/
+/*!
+  \brief     FDKaacEnc_AutoToParcor
+
+  conversion autocorrelation to reflection coefficients
+
+  \param pointer to input (acf)
+  \param pointer to output (reflection coefficients)
+  \param number of coefficients
+
+  \return prediction gain
+****************************************************************************/
+static INT FDKaacEnc_AutoToParcor(
+        FIXP_DBL *RESTRICT input,
+        FIXP_DBL *RESTRICT reflCoeff,
+        const INT numOfCoeff
+        )
+{
+  INT       i, j, scale=0;
+  FIXP_DBL  tmp, parcorWorkBuffer[TNS_MAX_ORDER];
+  INT       predictionGain = (INT)(TNS_PREDGAIN_SCALE);
+
+  FIXP_DBL *RESTRICT workBuffer = parcorWorkBuffer;
+  const FIXP_DBL  autoCorr_0 = input[0];
+
+  if((FIXP_DBL)input[0] == FL2FXCONST_DBL(0.0)) {
+    FDKmemclear(reflCoeff,numOfCoeff*sizeof(FIXP_DBL));
+    return(predictionGain);
+  }
+
+  FDKmemcpy(workBuffer,&input[1],numOfCoeff*sizeof(FIXP_DBL));
+  for(i=0; i<numOfCoeff; i++) {
+    LONG sign = ((LONG)workBuffer[0] >> (DFRACT_BITS-1));
+    tmp = (FIXP_DBL)((LONG)workBuffer[0]^sign);
+
+    if(input[0]<tmp)
+      break;
+
+    tmp = (FIXP_DBL)((LONG)schur_div(tmp, input[0], FRACT_BITS)^(~sign));
+    reflCoeff[i] = tmp;
+
+    for(j=numOfCoeff-i-1; j>=0; j--) {
+      FIXP_DBL accu1 = fMult(tmp, input[j]);
+      FIXP_DBL accu2 = fMult(tmp, workBuffer[j]);
+      workBuffer[j] += accu1;
+      input[j] += accu2;
+    }
+
+    workBuffer++;
+  }
+
+  tmp = fMult((FIXP_DBL)((LONG)TNS_PREDGAIN_SCALE<<21), fDivNorm(autoCorr_0, input[0], &scale));
+  predictionGain = (LONG)scaleValue(tmp,scale-21);
+
+  return (predictionGain);
+}
+
+
+static INT FDKaacEnc_Search3(FIXP_DBL parcor)
+{
+  INT i, index=0;
+
+  for(i=0;i<8;i++){
+    if(parcor > FDKaacEnc_tnsCoeff3Borders[i])
+      index=i;
+  }
+  return(index-4);
+}
+
+static INT FDKaacEnc_Search4(FIXP_DBL parcor)
+{
+  INT i, index=0;
+
+  for(i=0;i<16;i++){
+    if(parcor > FDKaacEnc_tnsCoeff4Borders[i])
+      index=i;
+  }
+  return(index-8);
+}
+
+
+/*****************************************************************************
+
+    functionname: FDKaacEnc_Parcor2Index
+
+*****************************************************************************/
+static void FDKaacEnc_Parcor2Index(
+        const FIXP_DBL *parcor,
+        INT *RESTRICT index,
+        const INT order,
+        const INT bitsPerCoeff
+        )
+{
+  INT i;
+  for(i=0; i<order; i++) {
+    if(bitsPerCoeff == 3)
+      index[i] = FDKaacEnc_Search3(parcor[i]);
+    else
+      index[i] = FDKaacEnc_Search4(parcor[i]);
+  }
+}
+
+
+/*****************************************************************************
+
+    functionname: FDKaacEnc_Index2Parcor
+    description:  inverse quantization for reflection coefficients
+    returns:      -
+    input:        quantized values, ptr. to reflection coefficients,
+                  no. of coefficients, resolution
+    output:       reflection coefficients
+
+*****************************************************************************/
+static void FDKaacEnc_Index2Parcor(
+        const INT *index,
+        FIXP_DBL *RESTRICT parcor,
+        const INT order,
+        const INT bitsPerCoeff
+        )
+{
+  INT i;
+  for(i=0; i<order; i++)
+    parcor[i] = bitsPerCoeff == 4 ? FDKaacEnc_tnsEncCoeff4[index[i]+8] : FDKaacEnc_tnsEncCoeff3[index[i]+4];
+}
+
+
+/*****************************************************************************
+
+    functionname: FDKaacEnc_ParcorToLpc
+    description:  conversion reflection coefficients to LPC coefficients
+    returns:      Gain factor
+    input:        reflection coefficients, no. of reflection coefficients <order>,
+                  ptr. to work buffer (required size: order)
+    output:       <order> LPC coefficients
+
+*****************************************************************************/
+static INT FDKaacEnc_ParcorToLpc(
+        const FIXP_DBL *reflCoeff,
+        FIXP_DBL *RESTRICT LpcCoeff,
+        const INT numOfCoeff,
+        FIXP_DBL *RESTRICT workBuffer
+        )
+{
+  INT i, j;
+  INT shiftval, par2LpcShiftVal = 6;  /* 6 should be enough, bec. max(numOfCoeff) = 20 */
+  FIXP_DBL maxVal = FL2FXCONST_DBL(0.0f);
+
+  LpcCoeff[0] = reflCoeff[0] >> par2LpcShiftVal;
+  for(i=1; i<numOfCoeff; i++) {
+    for(j=0; j<i; j++) {
+        workBuffer[j] = LpcCoeff[i-1-j];
+    }
+
+    for(j=0; j<i; j++) {
+        LpcCoeff[j] += fMult(reflCoeff[i],workBuffer[j]);
+    }
+
+    LpcCoeff[i] = reflCoeff[i] >> par2LpcShiftVal;
+  }
+
+  /* normalize LpcCoeff and calc shiftfactor */
+  for(i=0; i<numOfCoeff; i++) {
+      maxVal = fixMax(maxVal,(FIXP_DBL)fixp_abs(LpcCoeff[i]));
+  }
+
+  shiftval = CountLeadingBits(maxVal);
+  shiftval = (shiftval>=par2LpcShiftVal) ? par2LpcShiftVal : shiftval;
+
+  for(i=0; i<numOfCoeff; i++)
+      LpcCoeff[i] = LpcCoeff[i]<<shiftval;
+
+  return (par2LpcShiftVal - shiftval);
+}
+
+/***************************************************************************/
+/*!
+  \brief     FDKaacEnc_AnalysisFilter
+
+  TNS analysis filter (all-zero filter)
+
+  \param pointer to signal spectrum
+  \param number of lines
+  \param pointer to lpc coefficients
+  \param filter order
+  \param lpc gain factor
+
+  \return void
+****************************************************************************/
+/* Note: in-place computation possible */
+static void FDKaacEnc_AnalysisFilter(
+        FIXP_DBL *RESTRICT signal,
+        const INT numOfLines,
+        const FIXP_DBL *predictorCoeff,
+        const INT order,
+        const INT lpcGainFactor
+        )
+{
+  FIXP_DBL statusVar[TNS_MAX_ORDER];
+  INT i, j;
+  const INT shift = lpcGainFactor + 1;      /* +1, because fMultDiv2 */
+  FIXP_DBL tmp;
+
+  if (order>0) {
+
+    INT idx = 0;
+
+    /* keep filter coefficients twice and save memory copy operation in
+       modulo state buffer */
+#if defined(ARCH_PREFER_MULT_32x16)
+    FIXP_SGL  coeff[2*TNS_MAX_ORDER];
+    const FIXP_SGL *pCoeff;
+    for(i=0;i<order;i++) {
+      coeff[i]       = FX_DBL2FX_SGL(predictorCoeff[i]);
+    }
+    FDKmemcpy(&coeff[order], coeff, order*sizeof(FIXP_SGL));
+#else
+    FIXP_DBL  coeff[2*TNS_MAX_ORDER];
+    const FIXP_DBL *pCoeff;
+    FDKmemcpy(&coeff[0],     predictorCoeff, order*sizeof(FIXP_DBL));
+    FDKmemcpy(&coeff[order], predictorCoeff, order*sizeof(FIXP_DBL));
+#endif
+    FDKmemclear(statusVar, order*sizeof(FIXP_DBL));
+
+    for(j=0; j<numOfLines; j++) {
+      pCoeff = &coeff[(order-idx)];
+      tmp = FL2FXCONST_DBL(0);
+      for(i=0; i<order; i++) {
+          tmp = fMultAddDiv2(tmp, pCoeff[i], statusVar[i]) ;
+      }
+
+      if(--idx<0) { idx = order-1; }
+      statusVar[idx] = signal[j];
+
+      FDK_ASSERT(lpcGainFactor>=0);
+      signal[j] = (tmp<<shift) + signal[j];
+    }
+  }
+}
+
+