Include patched FDK-AAC in the repository

The initial idea was to get the DAB+ patch into upstream, but since
that follows the android source releases, there is no place for a custom
DAB+ patch there.

So instead of having to maintain a patched fdk-aac that has to have the
same .so version as the distribution package on which it is installed,
we prefer having a separate fdk-aac-dab library to avoid collision.

At that point, there's no reason to keep fdk-aac in a separate
repository, as odr-audioenc is the only tool that needs DAB+ encoding
support. Including it here simplifies installation, and makes it
consistent with toolame-dab, also shipped in this repository.

DAB+ decoding support (needed by ODR-SourceCompanion, dablin, etisnoop,
welle.io and others) can be done using upstream FDK-AAC.

1 files changed, 715 insertions, 0 deletions

diff --git a/fdk-aac/libDRCdec/src/drcGainDec_preprocess.cpp b/fdk-aac/libDRCdec/src/drcGainDec_preprocess.cpp
new file mode 100644
index 0000000..c543c53
--- /dev/null
+++ b/fdk-aac/libDRCdec/src/drcGainDec_preprocess.cpp
@@ -0,0 +1,715 @@
+/* -----------------------------------------------------------------------------
+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
+----------------------------------------------------------------------------- */
+
+/************************* MPEG-D DRC decoder library **************************
+
+   Author(s):
+
+   Description:
+
+*******************************************************************************/
+
+#include "drcDec_types.h"
+#include "drcDec_gainDecoder.h"
+#include "drcGainDec_preprocess.h"
+#include "drcDec_tools.h"
+#include "FDK_matrixCalloc.h"
+#include "drcDec_rom.h"
+
+#define SLOPE_FACTOR_DB_TO_LINEAR \
+  FL2FXCONST_DBL(0.1151f * (float)(1 << 3)) /* ln(10) / 20 */
+
+typedef struct {
+  int drcSetEffect;
+  DUCKING_MODIFICATION* pDMod;
+  GAIN_MODIFICATION* pGMod;
+  int drcCharacteristicPresent;
+  CHARACTERISTIC_FORMAT characteristicFormatSource[2];
+  const CUSTOM_DRC_CHAR* pCCharSource[2];
+  CHARACTERISTIC_FORMAT characteristicFormatTarget[2];
+  const CUSTOM_DRC_CHAR* pCCharTarget[2];
+  int slopeIsNegative;
+  int limiterPeakTargetPresent;
+  FIXP_SGL limiterPeakTarget;
+  FIXP_DBL loudnessNormalizationGainDb;
+  FIXP_SGL compress;
+  FIXP_SGL boost;
+} NODE_MODIFICATION;
+
+static DRC_ERROR _getCicpCharacteristic(
+    const int cicpCharacteristic,
+    CHARACTERISTIC_FORMAT pCharacteristicFormat[2],
+    const CUSTOM_DRC_CHAR* pCCharSource[2]) {
+  if ((cicpCharacteristic < 1) || (cicpCharacteristic > 11)) {
+    return DE_NOT_OK;
+  }
+
+  if (cicpCharacteristic < 7) { /* sigmoid characteristic */
+    pCharacteristicFormat[CS_LEFT] = CF_SIGMOID;
+    pCCharSource[CS_LEFT] =
+        (const CUSTOM_DRC_CHAR*)(&cicpDrcCharSigmoidLeft[cicpCharacteristic -
+                                                         1]);
+    pCharacteristicFormat[CS_RIGHT] = CF_SIGMOID;
+    pCCharSource[CS_RIGHT] =
+        (const CUSTOM_DRC_CHAR*)(&cicpDrcCharSigmoidRight[cicpCharacteristic -
+                                                          1]);
+  } else { /* nodes characteristic */
+    pCharacteristicFormat[CS_LEFT] = CF_NODES;
+    pCCharSource[CS_LEFT] =
+        (const CUSTOM_DRC_CHAR*)(&cicpDrcCharNodesLeft[cicpCharacteristic - 7]);
+    pCharacteristicFormat[CS_RIGHT] = CF_NODES;
+    pCCharSource[CS_RIGHT] =
+        (const CUSTOM_DRC_CHAR*)(&cicpDrcCharNodesRight[cicpCharacteristic -
+                                                        7]);
+  }
+  return DE_OK;
+}
+
+static int _getSign(FIXP_SGL in) {
+  if (in > (FIXP_DBL)0) return 1;
+  if (in < (FIXP_DBL)0) return -1;
+  return 0;
+}
+
+static DRC_ERROR _getSlopeSign(const CHARACTERISTIC_FORMAT drcCharFormat,
+                               const CUSTOM_DRC_CHAR* pCChar, int* pSlopeSign) {
+  if (drcCharFormat == CF_SIGMOID) {
+    *pSlopeSign = (pCChar->sigmoid.flipSign ? 1 : -1);
+  } else {
+    int k, slopeSign = 0, tmp_slopeSign;
+    for (k = 0; k < pCChar->nodes.characteristicNodeCount; k++) {
+      if (pCChar->nodes.nodeLevel[k + 1] > pCChar->nodes.nodeLevel[k]) {
+        tmp_slopeSign =
+            _getSign(pCChar->nodes.nodeGain[k + 1] - pCChar->nodes.nodeGain[k]);
+      } else {
+        tmp_slopeSign = -_getSign(pCChar->nodes.nodeGain[k + 1] -
+                                  pCChar->nodes.nodeGain[k]);
+      }
+      if ((slopeSign || tmp_slopeSign) && (slopeSign == -tmp_slopeSign))
+        return DE_NOT_OK; /* DRC characteristic is not invertible */
+      else
+        slopeSign = tmp_slopeSign;
+    }
+    *pSlopeSign = slopeSign;
+  }
+  return DE_OK;
+}
+
+static DRC_ERROR _isSlopeNegative(const CHARACTERISTIC_FORMAT drcCharFormat[2],
+                                  const CUSTOM_DRC_CHAR* pCChar[2],
+                                  int* pSlopeIsNegative) {
+  DRC_ERROR err = DE_OK;
+  int slopeSign[2] = {0, 0};
+
+  err = _getSlopeSign(drcCharFormat[CS_LEFT], pCChar[CS_LEFT],
+                      &slopeSign[CS_LEFT]);
+  if (err) return err;
+
+  err = _getSlopeSign(drcCharFormat[CS_RIGHT], pCChar[CS_RIGHT],
+                      &slopeSign[CS_RIGHT]);
+  if (err) return err;
+
+  if ((slopeSign[CS_LEFT] || slopeSign[CS_RIGHT]) &&
+      (slopeSign[CS_LEFT] == -slopeSign[CS_RIGHT]))
+    return DE_NOT_OK; /* DRC characteristic is not invertible */
+
+  *pSlopeIsNegative = (slopeSign[CS_LEFT] < 0);
+  return DE_OK;
+}
+
+static DRC_ERROR _prepareDrcCharacteristic(const DRC_CHARACTERISTIC* pDChar,
+                                           DRC_COEFFICIENTS_UNI_DRC* pCoef,
+                                           const int b,
+                                           NODE_MODIFICATION* pNodeMod) {
+  DRC_ERROR err = DE_OK;
+  pNodeMod->drcCharacteristicPresent = pDChar->present;
+  if (pNodeMod->drcCharacteristicPresent) {
+    if (pDChar->isCICP == 1) {
+      err = _getCicpCharacteristic(pDChar->cicpIndex,
+                                   pNodeMod->characteristicFormatSource,
+                                   pNodeMod->pCCharSource);
+      if (err) return err;
+    } else {
+      pNodeMod->characteristicFormatSource[CS_LEFT] =
+          (CHARACTERISTIC_FORMAT)
+              pCoef->characteristicLeftFormat[pDChar->custom.left];
+      pNodeMod->pCCharSource[CS_LEFT] =
+          &(pCoef->customCharacteristicLeft[pDChar->custom.left]);
+      pNodeMod->characteristicFormatSource[CS_RIGHT] =
+          (CHARACTERISTIC_FORMAT)
+              pCoef->characteristicRightFormat[pDChar->custom.right];
+      pNodeMod->pCCharSource[CS_RIGHT] =
+          &(pCoef->customCharacteristicRight[pDChar->custom.right]);
+    }
+    err = _isSlopeNegative(pNodeMod->characteristicFormatSource,
+                           pNodeMod->pCCharSource, &pNodeMod->slopeIsNegative);
+    if (err) return err;
+
+    if (pNodeMod->pGMod != NULL) {
+      if (pNodeMod->pGMod[b].targetCharacteristicLeftPresent) {
+        pNodeMod->characteristicFormatTarget[CS_LEFT] =
+            (CHARACTERISTIC_FORMAT)pCoef->characteristicLeftFormat
+                [pNodeMod->pGMod[b].targetCharacteristicLeftIndex];
+        pNodeMod->pCCharTarget[CS_LEFT] =
+            &(pCoef->customCharacteristicLeft
+                  [pNodeMod->pGMod[b].targetCharacteristicLeftIndex]);
+      }
+      if (pNodeMod->pGMod[b].targetCharacteristicRightPresent) {
+        pNodeMod->characteristicFormatTarget[CS_RIGHT] =
+            (CHARACTERISTIC_FORMAT)pCoef->characteristicRightFormat
+                [pNodeMod->pGMod[b].targetCharacteristicRightIndex];
+        pNodeMod->pCCharTarget[CS_RIGHT] =
+            &(pCoef->customCharacteristicRight
+                  [pNodeMod->pGMod[b].targetCharacteristicRightIndex]);
+      }
+    }
+  }
+  return DE_OK;
+}
+
+static DRC_ERROR _compressorIO_sigmoid_common(
+    const FIXP_DBL tmp,               /* e = 7 */
+    const FIXP_DBL gainDbLimit,       /* e = 6 */
+    const FIXP_DBL exp,               /* e = 5 */
+    const int inverse, FIXP_DBL* out) /* e = 7 */
+{
+  FIXP_DBL x, tmp1, tmp2, invExp, denom;
+  int e_x, e_tmp1, e_tmp2, e_invExp, e_denom, e_out;
+
+  if (exp < FL2FXCONST_DBL(1.0f / (float)(1 << 5))) {
+    return DE_NOT_OK;
+  }
+
+  /* x = tmp / gainDbLimit; */
+  x = fDivNormSigned(tmp, gainDbLimit, &e_x);
+  e_x += 7 - 6;
+  if (x < (FIXP_DBL)0) {
+    return DE_NOT_OK;
+  }
+
+  /* out = tmp / pow(1.0f +/- pow(x, exp), 1.0f/exp); */
+  tmp1 = fPow(x, e_x, exp, 5, &e_tmp1);
+  if (inverse) tmp1 = -tmp1;
+  tmp2 = fAddNorm(FL2FXCONST_DBL(1.0f / (float)(1 << 1)), 1, tmp1, e_tmp1,
+                  &e_tmp2);
+  invExp = fDivNorm(FL2FXCONST_DBL(1.0f / (float)(1 << 1)), exp, &e_invExp);
+  e_invExp += 1 - 5;
+  denom = fPow(tmp2, e_tmp2, invExp, e_invExp, &e_denom);
+  *out = fDivNormSigned(tmp, denom, &e_out);
+  e_out += 7 - e_denom;
+  *out = scaleValueSaturate(*out, e_out - 7);
+  return DE_OK;
+}
+
+static DRC_ERROR _compressorIO_sigmoid(const CUSTOM_DRC_CHAR_SIGMOID* pCChar,
+                                       const FIXP_DBL inLevelDb, /* e = 7 */
+                                       FIXP_DBL* outGainDb)      /* e = 7 */
+{
+  FIXP_DBL tmp;
+  FIXP_SGL exp = pCChar->exp;
+  DRC_ERROR err = DE_OK;
+
+  tmp = fMultDiv2((DRC_INPUT_LOUDNESS_TARGET >> 1) - (inLevelDb >> 1),
+                  pCChar->ioRatio);
+  tmp = SATURATE_LEFT_SHIFT(tmp, 2 + 1 + 1, DFRACT_BITS);
+  if (exp < (FIXP_SGL)MAXVAL_SGL) {
+    /* x = tmp / gainDbLimit; */
+    /* *outGainDb = tmp / pow(1.0f + pow(x, exp), 1.0f/exp); */
+    err = _compressorIO_sigmoid_common(tmp, FX_SGL2FX_DBL(pCChar->gain),
+                                       FX_SGL2FX_DBL(exp), 0, outGainDb);
+    if (err) return err;
+  } else {
+    *outGainDb =
+        tmp; /* scaling of outGainDb (7) is equal to scaling of tmp (7) */
+  }
+  if (pCChar->flipSign == 1) {
+    *outGainDb = -*outGainDb;
+  }
+  return err;
+}
+
+static DRC_ERROR _compressorIO_sigmoid_inverse(
+    const CUSTOM_DRC_CHAR_SIGMOID* pCChar, const FIXP_SGL gainDb,
+    FIXP_DBL* inLev) {
+  DRC_ERROR err = DE_OK;
+  FIXP_SGL ioRatio = pCChar->ioRatio;
+  FIXP_SGL exp = pCChar->exp;
+  FIXP_DBL tmp = FX_SGL2FX_DBL(gainDb), tmp_out;
+  int e_out;
+
+  if (pCChar->flipSign == 1) {
+    tmp = -tmp;
+  }
+  if (exp < (FIXP_SGL)MAXVAL_SGL) {
+    /* x = tmp / gainDbLimit; */
+    /* tmp = tmp / pow(1.0f - pow(x, exp), 1.0f / exp); */
+    err = _compressorIO_sigmoid_common(tmp, FX_SGL2FX_DBL(pCChar->gain),
+                                       FX_SGL2FX_DBL(exp), 1, &tmp);
+    if (err) return err;
+  }
+  if (ioRatio == (FIXP_SGL)0) {
+    return DE_NOT_OK;
+  }
+  tmp_out = fDivNormSigned(tmp, FX_SGL2FX_DBL(ioRatio), &e_out);
+  e_out += 7 - 2;
+  tmp_out = fAddNorm(DRC_INPUT_LOUDNESS_TARGET, 7, -tmp_out, e_out, &e_out);
+  *inLev = scaleValueSaturate(tmp_out, e_out - 7);
+
+  return err;
+}
+
+static DRC_ERROR _compressorIO_nodes(const CUSTOM_DRC_CHAR_NODES* pCChar,
+                                     const FIXP_DBL inLevelDb, /* e = 7 */
+                                     FIXP_DBL* outGainDb)      /* e = 7 */
+{
+  int n;
+  FIXP_DBL w;
+  const FIXP_SGL* nodeLevel = pCChar->nodeLevel;
+  const FIXP_SGL* nodeGain = pCChar->nodeGain;
+
+  if (inLevelDb < DRC_INPUT_LOUDNESS_TARGET) {
+    for (n = 0; n < pCChar->characteristicNodeCount; n++) {
+      if ((inLevelDb <= FX_SGL2FX_DBL(nodeLevel[n])) &&
+          (inLevelDb > FX_SGL2FX_DBL(nodeLevel[n + 1]))) {
+        w = fDivNorm(inLevelDb - FX_SGL2FX_DBL(nodeLevel[n + 1]),
+                     FX_SGL2FX_DBL(nodeLevel[n] - nodeLevel[n + 1]));
+        *outGainDb = fMult(w, nodeGain[n]) +
+                     fMult((FIXP_DBL)MAXVAL_DBL - w, nodeGain[n + 1]);
+        /* *outGainDb = (w * nodeGain[n] + (1.0-w) * nodeGain[n+1]); */
+        return DE_OK;
+      }
+    }
+  } else {
+    for (n = 0; n < pCChar->characteristicNodeCount; n++) {
+      if ((inLevelDb >= FX_SGL2FX_DBL(nodeLevel[n])) &&
+          (inLevelDb < FX_SGL2FX_DBL(nodeLevel[n + 1]))) {
+        w = fDivNorm(FX_SGL2FX_DBL(nodeLevel[n + 1]) - inLevelDb,
+                     FX_SGL2FX_DBL(nodeLevel[n + 1] - nodeLevel[n]));
+        *outGainDb = fMult(w, nodeGain[n]) +
+                     fMult((FIXP_DBL)MAXVAL_DBL - w, nodeGain[n + 1]);
+        /* *outGainDb = (w * nodeGain[n] + (1.0-w) * nodeGain[n+1]); */
+        return DE_OK;
+      }
+    }
+  }
+  *outGainDb = FX_SGL2FX_DBL(nodeGain[pCChar->characteristicNodeCount]);
+  return DE_OK;
+}
+
+static DRC_ERROR _compressorIO_nodes_inverse(
+    const CUSTOM_DRC_CHAR_NODES* pCChar, const FIXP_SGL gainDb, /* e = 7 */
+    FIXP_DBL* inLev)                                            /* e = 7 */
+{
+  int n;
+  int k;
+  FIXP_DBL w;
+  int gainIsNegative = 0;
+  const FIXP_SGL* nodeLevel = pCChar->nodeLevel;
+  const FIXP_SGL* nodeGain = pCChar->nodeGain;
+  int nodeCount = pCChar->characteristicNodeCount;
+  for (k = 0; k < nodeCount; k++) {
+    if (pCChar->nodeGain[k + 1] < (FIXP_SGL)0) {
+      gainIsNegative = 1;
+    }
+  }
+  if (gainIsNegative == 1) {
+    if (gainDb <= nodeGain[nodeCount]) {
+      *inLev = FX_SGL2FX_DBL(nodeLevel[nodeCount]);
+    } else {
+      if (gainDb >= (FIXP_SGL)0) {
+        *inLev = DRC_INPUT_LOUDNESS_TARGET;
+      } else {
+        for (n = 0; n < nodeCount; n++) {
+          if ((gainDb <= nodeGain[n]) && (gainDb > nodeGain[n + 1])) {
+            FIXP_SGL gainDelta = nodeGain[n] - nodeGain[n + 1];
+            if (gainDelta == (FIXP_SGL)0) {
+              *inLev = FX_SGL2FX_DBL(nodeLevel[n]);
+              return DE_OK;
+            }
+            w = fDivNorm(gainDb - nodeGain[n + 1], gainDelta);
+            *inLev = fMult(w, nodeLevel[n]) +
+                     fMult((FIXP_DBL)MAXVAL_DBL - w, nodeLevel[n + 1]);
+            /* *inLev = (w * nodeLevel[n] + (1.0-w) * nodeLevel[n+1]); */
+            return DE_OK;
+          }
+        }
+        *inLev = FX_SGL2FX_DBL(nodeLevel[nodeCount]);
+      }
+    }
+  } else {
+    if (gainDb >= nodeGain[nodeCount]) {
+      *inLev = FX_SGL2FX_DBL(nodeLevel[nodeCount]);
+    } else {
+      if (gainDb <= (FIXP_SGL)0) {
+        *inLev = DRC_INPUT_LOUDNESS_TARGET;
+      } else {
+        for (n = 0; n < nodeCount; n++) {
+          if ((gainDb >= nodeGain[n]) && (gainDb < nodeGain[n + 1])) {
+            FIXP_SGL gainDelta = nodeGain[n + 1] - nodeGain[n];
+            if (gainDelta == (FIXP_SGL)0) {
+              *inLev = FX_SGL2FX_DBL(nodeLevel[n]);
+              return DE_OK;
+            }
+            w = fDivNorm(nodeGain[n + 1] - gainDb, gainDelta);
+            *inLev = fMult(w, nodeLevel[n]) +
+                     fMult((FIXP_DBL)MAXVAL_DBL - w, nodeLevel[n + 1]);
+            /* *inLev = (w * nodeLevel[n] + (1.0-w) * nodeLevel[n+1]); */
+            return DE_OK;
+          }
+        }
+        *inLev = FX_SGL2FX_DBL(nodeLevel[nodeCount]);
+      }
+    }
+  }
+  return DE_OK;
+}
+
+static DRC_ERROR _mapGain(const CHARACTERISTIC_FORMAT pCCharFormatSource,
+                          const CUSTOM_DRC_CHAR* pCCharSource,
+                          const CHARACTERISTIC_FORMAT pCCharFormatTarget,
+                          const CUSTOM_DRC_CHAR* pCCharTarget,
+                          const FIXP_SGL gainInDb, /* e = 7 */
+                          FIXP_DBL* gainOutDb)     /* e = 7 */
+{
+  FIXP_DBL inLevel = (FIXP_DBL)0;
+  DRC_ERROR err = DE_OK;
+
+  switch (pCCharFormatSource) {
+    case CF_SIGMOID:
+      err = _compressorIO_sigmoid_inverse(
+          (const CUSTOM_DRC_CHAR_SIGMOID*)pCCharSource, gainInDb, &inLevel);
+      if (err) return err;
+      break;
+    case CF_NODES:
+      err = _compressorIO_nodes_inverse(
+          (const CUSTOM_DRC_CHAR_NODES*)pCCharSource, gainInDb, &inLevel);
+      if (err) return err;
+      break;
+    default:
+      return DE_NOT_OK;
+  }
+  switch (pCCharFormatTarget) {
+    case CF_SIGMOID:
+      err = _compressorIO_sigmoid((const CUSTOM_DRC_CHAR_SIGMOID*)pCCharTarget,
+                                  inLevel, gainOutDb);
+      if (err) return err;
+      break;
+    case CF_NODES:
+      err = _compressorIO_nodes((const CUSTOM_DRC_CHAR_NODES*)pCCharTarget,
+                                inLevel, gainOutDb);
+      if (err) return err;
+      break;
+    default:
+      break;
+  }
+  return DE_OK;
+}
+
+static DRC_ERROR _toLinear(
+    const NODE_MODIFICATION* nodeMod, const int drcBand,
+    const FIXP_SGL gainDb,  /* in: gain value in dB, e = 7 */
+    const FIXP_SGL slopeDb, /* in: slope value in dB/deltaTmin, e = 2 */
+    FIXP_DBL* gainLin,      /* out: linear gain value, e = 7 */
+    FIXP_DBL* slopeLin)     /* out: linear slope value, e = 7 */
+{
+  FIXP_DBL gainRatio_m = FL2FXCONST_DBL(1.0f / (float)(1 << 1));
+  GAIN_MODIFICATION* pGMod = NULL;
+  DUCKING_MODIFICATION* pDMod = nodeMod->pDMod;
+  FIXP_DBL tmp_dbl, gainDb_modified, gainDb_offset, gainDb_out, gainLin_m,
+      slopeLin_m;
+  int gainLin_e, gainRatio_e = 1, gainDb_out_e;
+  if (nodeMod->pGMod != NULL) {
+    pGMod = &(nodeMod->pGMod[drcBand]);
+  }
+  if (((nodeMod->drcSetEffect & (EB_DUCK_OTHER | EB_DUCK_SELF)) == 0) &&
+      (nodeMod->drcSetEffect != EB_FADE) &&
+      (nodeMod->drcSetEffect != EB_CLIPPING)) {
+    DRC_ERROR err = DE_OK;
+    FIXP_DBL gainDbMapped;
+
+    if ((pGMod != NULL) && (nodeMod->drcCharacteristicPresent)) {
+      if (((gainDb > (FIXP_SGL)0) && nodeMod->slopeIsNegative) ||
+          ((gainDb < (FIXP_SGL)0) && !nodeMod->slopeIsNegative)) {
+        /* left side */
+        if (pGMod->targetCharacteristicLeftPresent == 1) {
+          err = _mapGain(nodeMod->characteristicFormatSource[CS_LEFT],
+                         nodeMod->pCCharSource[CS_LEFT],
+                         nodeMod->characteristicFormatTarget[CS_LEFT],
+                         nodeMod->pCCharTarget[CS_LEFT], gainDb, &gainDbMapped);
+          if (err) return err;
+          gainRatio_m = fDivNormSigned(
+              gainDbMapped, FX_SGL2FX_DBL(gainDb),
+              &gainRatio_e); /* target characteristic in payload */
+        }
+      }
+
+      else { /* if (((gainDb < (FIXP_SGL)0) && nodeMod->slopeIsNegative) ||
+                ((gainDb > (FIXP_SGL)0) && !nodeMod->slopeIsNegative)) */
+
+        /* right side */
+        if (pGMod->targetCharacteristicRightPresent == 1) {
+          err =
+              _mapGain(nodeMod->characteristicFormatSource[CS_RIGHT],
+                       nodeMod->pCCharSource[CS_RIGHT],
+                       nodeMod->characteristicFormatTarget[CS_RIGHT],
+                       nodeMod->pCCharTarget[CS_RIGHT], gainDb, &gainDbMapped);
+          if (err) return err;
+          gainRatio_m = fDivNormSigned(
+              gainDbMapped, FX_SGL2FX_DBL(gainDb),
+              &gainRatio_e); /* target characteristic in payload */
+        }
+      }
+    }
+    if (gainDb < (FIXP_SGL)0) {
+      gainRatio_m = fMultDiv2(gainRatio_m, nodeMod->compress);
+    } else {
+      gainRatio_m = fMultDiv2(gainRatio_m, nodeMod->boost);
+    }
+    gainRatio_e += 2;
+  }
+  if ((pGMod != NULL) && (pGMod->gainScalingPresent == 1)) {
+    if (gainDb < (FIXP_SGL)0) {
+      gainRatio_m = fMultDiv2(gainRatio_m, pGMod->attenuationScaling);
+    } else {
+      gainRatio_m = fMultDiv2(gainRatio_m, pGMod->amplificationScaling);
+    }
+    gainRatio_e += 3;
+  }
+  if ((pDMod != NULL) &&
+      (nodeMod->drcSetEffect & (EB_DUCK_OTHER | EB_DUCK_SELF)) &&
+      (pDMod->duckingScalingPresent == 1)) {
+    gainRatio_m = fMultDiv2(gainRatio_m, pDMod->duckingScaling);
+    gainRatio_e += 3;
+  }
+
+  gainDb_modified =
+      fMultDiv2(gainDb, gainRatio_m); /* resulting e: 7 + gainRatio_e + 1*/
+  gainDb_offset = (FIXP_DBL)0;
+
+  if ((pGMod != NULL) && (pGMod->gainOffsetPresent == 1)) {
+    /* *gainLin *= (float)pow(2.0, (double)(pGMod->gainOffset/6.0f)); */
+    gainDb_offset += FX_SGL2FX_DBL(pGMod->gainOffset) >> 4; /* resulting e: 8 */
+  }
+  if ((nodeMod->limiterPeakTargetPresent == 1) &&
+      (nodeMod->drcSetEffect ==
+       EB_CLIPPING)) { /* The only drcSetEffect is "clipping prevention" */
+    /* loudnessNormalizationGainModificationDb is included in
+     * loudnessNormalizationGainDb */
+    /* *gainLin *= (float)pow(2.0, max(0.0, -nodeModification->limiterPeakTarget
+     * - nodeModification->loudnessNormalizationGainDb)/6.0); */
+    gainDb_offset += fMax(
+        (FIXP_DBL)0,
+        (FX_SGL2FX_DBL(-nodeMod->limiterPeakTarget) >> 3) -
+            (nodeMod->loudnessNormalizationGainDb >> 1)); /* resulting e: 8 */
+  }
+  if (gainDb_offset != (FIXP_DBL)0) {
+    gainDb_out = fAddNorm(gainDb_modified, 7 + gainRatio_e + 1, gainDb_offset,
+                          8, &gainDb_out_e);
+  } else {
+    gainDb_out = gainDb_modified;
+    gainDb_out_e = 7 + gainRatio_e + 1;
+  }
+
+  /* *gainLin = (float)pow(2.0, (double)(gainDb_modified[1] / 6.0f)); */
+  gainLin_m = approxDb2lin(gainDb_out, gainDb_out_e, &gainLin_e);
+  *gainLin = scaleValueSaturate(gainLin_m, gainLin_e - 7);
+
+  /* *slopeLin = SLOPE_FACTOR_DB_TO_LINEAR * gainRatio * *gainLin * slopeDb; */
+  if (slopeDb == (FIXP_SGL)0) {
+    *slopeLin = (FIXP_DBL)0;
+  } else {
+    tmp_dbl =
+        fMult(slopeDb, SLOPE_FACTOR_DB_TO_LINEAR); /* resulting e: 2 - 3 = -1 */
+    tmp_dbl = fMult(tmp_dbl, gainRatio_m); /* resulting e: -1 + gainRatio_e */
+    if (gainDb_offset !=
+        (FIXP_DBL)0) { /* recalculate gainLin from gainDb that wasn't modified
+                          by gainOffset and limiterPeakTarget */
+      gainLin_m = approxDb2lin(gainDb_modified, 7 + gainRatio_e, &gainLin_e);
+    }
+    slopeLin_m = fMult(tmp_dbl, gainLin_m);
+    *slopeLin =
+        scaleValueSaturate(slopeLin_m, -1 + gainRatio_e + gainLin_e - 7);
+  }
+
+  if ((nodeMod->limiterPeakTargetPresent == 1) &&
+      (nodeMod->drcSetEffect == EB_CLIPPING)) {
+    if (*gainLin >= FL2FXCONST_DBL(1.0f / (float)(1 << 7))) {
+      *gainLin = FL2FXCONST_DBL(1.0f / (float)(1 << 7));
+      *slopeLin = (FIXP_DBL)0;
+    }
+  }
+
+  return DE_OK;
+}
+
+/* prepare buffers containing linear nodes for each gain sequence */
+DRC_ERROR
+prepareDrcGain(HANDLE_DRC_GAIN_DECODER hGainDec,
+               HANDLE_UNI_DRC_GAIN hUniDrcGain, const FIXP_SGL compress,
+               const FIXP_SGL boost, const FIXP_DBL loudnessNormalizationGainDb,
+               const int activeDrcIndex) {
+  int b, g, gainElementIndex;
+  DRC_GAIN_BUFFERS* drcGainBuffers = &(hGainDec->drcGainBuffers);
+  NODE_MODIFICATION nodeMod;
+  FDKmemclear(&nodeMod, sizeof(NODE_MODIFICATION));
+  ACTIVE_DRC* pActiveDrc = &(hGainDec->activeDrc[activeDrcIndex]);
+  DRC_INSTRUCTIONS_UNI_DRC* pInst = pActiveDrc->pInst;
+  if (pInst == NULL) return DE_NOT_OK;
+
+  nodeMod.drcSetEffect = pInst->drcSetEffect;
+
+  nodeMod.compress = compress;
+  nodeMod.boost = boost;
+  nodeMod.loudnessNormalizationGainDb = loudnessNormalizationGainDb;
+  nodeMod.limiterPeakTargetPresent = pInst->limiterPeakTargetPresent;
+  nodeMod.limiterPeakTarget = pInst->limiterPeakTarget;
+
+  gainElementIndex = 0;
+  for (g = 0; g < pInst->nDrcChannelGroups; g++) {
+    int gainSetIndex = 0;
+    int nDrcBands = 0;
+    DRC_COEFFICIENTS_UNI_DRC* pCoef = pActiveDrc->pCoef;
+    if (pCoef == NULL) return DE_NOT_OK;
+
+    if (!pActiveDrc->channelGroupIsParametricDrc[g]) {
+      gainSetIndex = pInst->gainSetIndexForChannelGroup[g];
+
+      if (nodeMod.drcSetEffect & (EB_DUCK_OTHER | EB_DUCK_SELF)) {
+        nodeMod.pDMod = &(pActiveDrc->duckingModificationForChannelGroup[g]);
+        nodeMod.pGMod = NULL;
+      } else {
+        nodeMod.pGMod = pInst->gainModificationForChannelGroup[g];
+        nodeMod.pDMod = NULL;
+      }
+
+      nDrcBands = pActiveDrc->bandCountForChannelGroup[g];
+      for (b = 0; b < nDrcBands; b++) {
+        DRC_ERROR err = DE_OK;
+        GAIN_SET* pGainSet = &(pCoef->gainSet[gainSetIndex]);
+        int seq = pGainSet->gainSequenceIndex[b];
+        DRC_CHARACTERISTIC* pDChar = &(pGainSet->drcCharacteristic[b]);
+
+        /* linearNodeBuffer contains a copy of the gain sequences (consisting of
+           nodes) that are relevant for decoding. It also contains gain
+           sequences of previous frames. */
+        LINEAR_NODE_BUFFER* pLnb =
+            &(drcGainBuffers->linearNodeBuffer[pActiveDrc->activeDrcOffset +
+                                               gainElementIndex]);
+        int i, lnbp;
+        lnbp = drcGainBuffers->lnbPointer;
+        pLnb->gainInterpolationType =
+            (GAIN_INTERPOLATION_TYPE)pGainSet->gainInterpolationType;
+
+        err = _prepareDrcCharacteristic(pDChar, pCoef, b, &nodeMod);
+        if (err) return err;
+
+        /* copy a node buffer and convert from dB to linear */
+        pLnb->nNodes[lnbp] = fMin((int)hUniDrcGain->nNodes[seq], 16);
+        for (i = 0; i < pLnb->nNodes[lnbp]; i++) {
+          FIXP_DBL gainLin, slopeLin;
+          err = _toLinear(&nodeMod, b, hUniDrcGain->gainNode[seq][i].gainDb,
+                          (FIXP_SGL)0, &gainLin, &slopeLin);
+          if (err) return err;
+          pLnb->linearNode[lnbp][i].gainLin = gainLin;
+          pLnb->linearNode[lnbp][i].time = hUniDrcGain->gainNode[seq][i].time;
+        }
+        gainElementIndex++;
+      }
+    } else {
+      /* parametric DRC not supported */
+      gainElementIndex++;
+    }
+  }
+  return DE_OK;
+}