/libPCMutils/src/pcmutils_lib.cpp

/* -----------------------------------------------------------------------------------------------------------
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
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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
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of the MPEG specifications.

Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
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Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality,
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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
----------------------------------------------------------------------------------------------------------- */

/****************************  FDK PCM utils module  **************************

   Author(s):   Christian Griebel
   Description: Defines functions to interface with the PCM post processing
                module.

*******************************************************************************/

#include "pcmutils_lib.h"

#include "genericStds.h"
#include "fixpoint_math.h"

/* Decoder library info */
#define PCMDMX_LIB_VL0 2
#define PCMDMX_LIB_VL1 3
#define PCMDMX_LIB_VL2 1
#define PCMDMX_LIB_TITLE "PCM Downmix Lib"
#define PCMDMX_LIB_BUILD_DATE __DATE__
#define PCMDMX_LIB_BUILD_TIME __TIME__

/* Library settings */
#define PCM_DMX_MAX_DELAY_FRAMES        ( 1 )
#define PCM_DMX_MAX_CHANNELS            ( 8 )
#define PCM_DMX_MAX_CHANNEL_GROUPS      ( 4 )
#define PCM_DMX_MAX_CHANNELS_PER_GROUP  ( 3 )   /* The maximum over all groups */
#define PCMDMX_DFLT_EXPIRY_FRAME        ( 50 )  /* At least 500ms (FL 960 @ 96kHz) */

/* Fixed and unique channel group indices.
 * The last group index has to be smaller than PCM_DMX_MAX_CHANNEL_GROUPS. */
#define CH_GROUP_FRONT ( 0 )
#define CH_GROUP_SIDE  ( 1 )
#define CH_GROUP_REAR  ( 2 )
#define CH_GROUP_LFE   ( 3 )

/* The ordering of the following fixed channel labels has to be in MPEG-4 style.
 * From the center to the back with left and right channel interleaved (starting with left).
 * The last channel label index has to be smaller than PCM_DMX_MAX_CHANNELS. */
#define CENTER_FRONT_CHANNEL    ( 0 )     /* C  */
#define LEFT_FRONT_CHANNEL      ( 1 )     /* L  */
#define RIGHT_FRONT_CHANNEL     ( 2 )     /* R  */
#define LEFT_OUTSIDE_CHANNEL    ( 3 )     /* Lo */
#define RIGHT_OUTSIDE_CHANNEL   ( 4 )     /* Ro */
#define LEFT_REAR_CHANNEL       ( 5 )     /* Lr  aka left back channel  */
#define RIGHT_REAR_CHANNEL      ( 6 )     /* Rr  aka right back channel */
#define LOW_FREQUENCY_CHANNEL   ( 7 )     /* Lf */

/* More constants */
#define ANC_DATA_SYNC_BYTE      ( 0xBC )  /* ancillary data sync byte. */
#define ATTENUATION_FACTOR_1    ( FL2FXCONST_SGL(0.70710678f) )
#define TWO_CHANNEL             ( 2 )

/* Sanity checks on library setting: */

/* List of packed channel modes */
typedef enum
{ /* CH_MODE_<numFrontCh>_<numOutsideCh>_<numRearCh>_<numLfCh> */
  CH_MODE_UNDEFINED = 0x0000,
  /* 1 channel */
  CH_MODE_1_0_0_0   = 0x0001,   /* chCfg 1 */
  /* 2 channels */
  CH_MODE_2_0_0_0   = 0x0002,   /* chCfg 2 */
  /* 3 channels */
  CH_MODE_3_0_0_0   = 0x0003,   /* chCfg 3 */
  CH_MODE_2_0_1_0   = 0x0102,
  CH_MODE_2_0_0_1   = 0x1002,
  /* 4 channels */
  CH_MODE_3_0_1_0   = 0x0103,   /* chCfg 4 */
  CH_MODE_2_0_2_0   = 0x0202,
  CH_MODE_2_0_1_1   = 0x1102,
  /* 5 channels */
  CH_MODE_3_0_2_0   = 0x0203,   /* chCfg 5 */
  CH_MODE_2_0_2_1   = 0x1202,
  CH_MODE_3_0_1_1   = 0x1103,
  CH_MODE_3_2_0_0   = 0x0023,
  /* 6 channels */
  CH_MODE_3_0_2_1   = 0x1203,   /* chCfg 6 */
  CH_MODE_3_2_1_0   = 0x0123,
  /* 7 channels */
  CH_MODE_2_2_2_1   = 0x1222,
  CH_MODE_3_2_1_1   = 0x1123,
  CH_MODE_3_2_2_0   = 0x0223,
  /* 8 channels */
  CH_MODE_3_2_2_1   = 0x1222,   /* chCfg 7 */
  CH_MODE_3_2_1_2   = 0x2123,
  CH_MODE_2_2_2_2   = 0x2222

} PCM_DMX_CHANNEL_MODE;


/* These are the channel configurations linked to
   the number of output channels give by the user: */
static const PCM_DMX_CHANNEL_MODE outChModeTable[PCM_DMX_MAX_CHANNELS] =
{
  CH_MODE_1_0_0_0,  /* 1 channel  */
  CH_MODE_2_0_0_0,  /* 2 channels */
  CH_MODE_3_0_0_0,  /* 3 channels */
  CH_MODE_3_0_1_0,  /* 4 channels */
  CH_MODE_3_0_2_0,  /* 5 channels */
  CH_MODE_3_0_2_1,  /* 6 channels */
  CH_MODE_3_2_2_0,  /* 7 channels */
  CH_MODE_3_2_2_1   /* 8 channels */
};

static const FIXP_SGL dvbDownmixFactors[8] =
{
  FL2FXCONST_SGL(1.0f),
  FL2FXCONST_SGL(0.841f),
  FL2FXCONST_SGL(0.707f),
  FL2FXCONST_SGL(0.596f),
  FL2FXCONST_SGL(0.500f),
  FL2FXCONST_SGL(0.422f),
  FL2FXCONST_SGL(0.355f),
  FL2FXCONST_SGL(0.0f)
};


  /* MPEG matrix mixdown:
      Set 1:  L' = (1 + 2^-0.5 + A )^-1 * [L + C * 2^-0.5 + A * Ls];
              R' = (1 + 2^-0.5 + A )^-1 * [R + C * 2^-0.5 + A * Rs];

      Set 2:  L' = (1 + 2^-0.5 + 2A )^-1 * [L + C * 2^-0.5 - A * (Ls + Rs)];
              R' = (1 + 2^-0.5 + 2A )^-1 * [R + C * 2^-0.5 + A * (Ls + Rs)];

      M = (3 + 2A)^-1 * [L + C + R + A*(Ls + Rs)];
  */
  static const FIXP_SGL mpegMixDownIdx2Coef[4] =
  {
    FL2FXCONST_SGL(0.70710678f),
    FL2FXCONST_SGL(0.5f),
    FL2FXCONST_SGL(0.35355339f),
    FL2FXCONST_SGL(0.0f)
  };

  static const FIXP_SGL mpegMixDownIdx2PreFact[4] =
  {
    FL2FXCONST_SGL(0.4142135623730950f),
    FL2FXCONST_SGL(0.4530818393219728f),
    FL2FXCONST_SGL(0.4852813742385703f),
    FL2FXCONST_SGL(0.5857864376269050f)
  };

  typedef struct
  {
    USHORT  matrixMixdownIdx;       /*!< MPEG mixdown index extracted from PCE.            */
    USHORT  pseudoSurroundEnable;   /*!< Pseudo surround enable flag extracted from PCE.   */
    USHORT  mixdownAvailable;       /*!< Will be set to 1 if we found a valid coefficient. */

  } MPEG_MIXDOWN_INFO;


typedef struct
{
  FIXP_SGL  centerMixLevelValue;    /*!< DVB mixdown level for the center channel extracted from anc data.  */
  FIXP_SGL  surroundMixLevelValue;  /*!< DVB mixdown level for back channels extracted from anc data.       */

  UCHAR     mixLevelsAvail;         /*!< Will be set to 1 if we found a valid coefficient.                  */

} DVB_MIXDOWN_LEVELS;


/* Modules main data structure: */
struct PCM_DMX_INSTANCE
{
  DVB_MIXDOWN_LEVELS  dvbMixDownLevels[PCM_DMX_MAX_DELAY_FRAMES+1];
  MPEG_MIXDOWN_INFO   mpegMixDownInfo[PCM_DMX_MAX_DELAY_FRAMES+1];
  DUAL_CHANNEL_MODE dualChannelMode;
  UINT expiryFrame;
  UINT expiryCount;
  SHORT numOutputChannels;
  UCHAR applyProcessing;
  UCHAR frameDelay;
};

/* Memory allocation macro */
C_ALLOC_MEM_STATIC(PcmDmxInstance, struct PCM_DMX_INSTANCE, 1)


/** Evaluate a given channel configuration and extract a packed channel mode and generate a channel offset table
 *  This function is the inverse to the getChannelDescription() routine.
 * @param [in] The total number of channels of the given configuration.
 * @param [in] Array holding the corresponding channel types for each channel.
 * @param [in] Array holding the corresponding channel type indices for each channel.
 * @param [out] Array where the buffer offsets for each channel are stored into.
 * @returns Returns the packed channel mode.
 **/
static
PCM_DMX_CHANNEL_MODE getChannelMode (
        const INT                numChannels,                           /* in */
        const AUDIO_CHANNEL_TYPE channelType[],                         /* in */
        const UCHAR              channelIndices[],                      /* in */
        UCHAR                    offsetTable[PCM_DMX_MAX_CHANNELS]      /* out */
      )
{
  UINT  chMode = CH_MODE_UNDEFINED;
  UCHAR chIdx[PCM_DMX_MAX_CHANNEL_GROUPS][PCM_DMX_MAX_CHANNELS_PER_GROUP];
  UCHAR numChInGrp[PCM_DMX_MAX_CHANNEL_GROUPS];
  int   ch, grpIdx, err = 0;

  FDK_ASSERT(channelType != NULL);
  FDK_ASSERT(channelIndices != NULL);
  FDK_ASSERT(offsetTable != NULL);

  /* For details see ISO/IEC 13818-7:2005(E), 8.5.3 Channel configuration */
  FDKmemclear(numChInGrp, PCM_DMX_MAX_CHANNEL_GROUPS*sizeof(UCHAR));
  FDKmemset(offsetTable, 255, PCM_DMX_MAX_CHANNELS*sizeof(UCHAR));
  FDKmemset(chIdx, 255, PCM_DMX_MAX_CHANNEL_GROUPS*PCM_DMX_MAX_CHANNELS_PER_GROUP*sizeof(UCHAR));

  /* Categorize channels */
  for (ch = 0; ch < numChannels; ch += 1) {
    int i = 0, j, chGrpIdx = channelIndices[ch];

    switch (channelType[ch]) {
    case ACT_FRONT:
    case ACT_FRONT_TOP:
      grpIdx = CH_GROUP_FRONT;
      break;
    case ACT_SIDE:
    case ACT_SIDE_TOP:
      grpIdx = CH_GROUP_SIDE;
      break;
    case ACT_BACK:
    case ACT_BACK_TOP:
      grpIdx = CH_GROUP_REAR;
      break;
    case ACT_LFE:
      grpIdx = CH_GROUP_LFE;
      break;
    default:
      err = -1;
      continue;
    }

    if (numChInGrp[grpIdx] < PCM_DMX_MAX_CHANNELS_PER_GROUP) {
      /* Sort channels by index */
      while ( (i < numChInGrp[grpIdx]) && (chGrpIdx > channelIndices[chIdx[grpIdx][i]]) ) {
        i += 1;
      }
      for (j = numChInGrp[grpIdx]; j > i; j -= 1) {
        chIdx[grpIdx][j] = chIdx[grpIdx][j-1];
      }
      chIdx[grpIdx][i] = ch;
      numChInGrp[grpIdx] += 1;
    }
  }

  /* Compose channel offset table */

  /* Non-symmetric channels */
  if (numChInGrp[CH_GROUP_FRONT] & 0x1) {
    /* Odd number of front channels -> we have a center channel.
       In MPEG-4 the center has the index 0. */
    offsetTable[CENTER_FRONT_CHANNEL] = chIdx[CH_GROUP_FRONT][0];
  }

  for (grpIdx = 0; grpIdx < PCM_DMX_MAX_CHANNEL_GROUPS; grpIdx += 1) {
    int chMapPos, maxChannels = 0;
    ch = 0;

    switch (grpIdx) {
    case CH_GROUP_FRONT:
      chMapPos = LEFT_FRONT_CHANNEL;
      maxChannels = 3;
      ch = numChInGrp[grpIdx] & 0x1;
      break;
    case CH_GROUP_SIDE:
      chMapPos = LEFT_OUTSIDE_CHANNEL;
      maxChannels = 2;
      break;
    case CH_GROUP_REAR:
      chMapPos = LEFT_REAR_CHANNEL;
      maxChannels = 2;
      break;
    case CH_GROUP_LFE:
      chMapPos = LOW_FREQUENCY_CHANNEL;
      maxChannels = 1;
      break;
    default:
      err = -1;
      continue;
    }

    for ( ; ch < numChInGrp[grpIdx]; ch += 1) {
      if (ch < maxChannels) {
        offsetTable[chMapPos] = chIdx[grpIdx][ch];
        chMapPos += 1;
      } else {
        err = -1;
      }
    }
  }

  if (err == 0) {
    /* Compose the channel mode */
    chMode = (numChInGrp[CH_GROUP_LFE]   & 0xF) << 12
           | (numChInGrp[CH_GROUP_REAR]  & 0xF) <<  8
           | (numChInGrp[CH_GROUP_SIDE]  & 0xF) <<  4
           | (numChInGrp[CH_GROUP_FRONT] & 0xF);
  }

  return (PCM_DMX_CHANNEL_MODE)chMode;
}


/** Generate a channel offset table and complete channel description for a given (packed) channel mode.
 *  This function is the inverse to the getChannelMode() routine.
 * @param [in] The total number of channels of the given configuration.
 * @param [in] Array containing the channel mapping to be used (From MPEG PCE ordering to whatever is required).
 * @param [out] Array where corresponding channel types for each channels are stored into.
 * @param [out] Array where corresponding channel type indices for each output channel are stored into.
 * @param [out] Array where the buffer offsets for each channel are stored into.
 * @returns None.
 **/
void getChannelDescription (
        const PCM_DMX_CHANNEL_MODE  chMode,                                 /* in */
        const UCHAR                 channelMapping[][PCM_DMX_MAX_CHANNELS], /* in */
        AUDIO_CHANNEL_TYPE          channelType[],                          /* out */
        UCHAR                       channelIndices[],                       /* out */
        UCHAR                       offsetTable[PCM_DMX_MAX_CHANNELS]       /* out */
      )
{
  const UCHAR *pChannelMap;
  int   grpIdx, ch = 0, numChannels = 0;
  UCHAR numChInGrp[PCM_DMX_MAX_CHANNEL_GROUPS];

  FDK_ASSERT(channelType != NULL);
  FDK_ASSERT(channelIndices != NULL);
  FDK_ASSERT(channelMapping != NULL);
  FDK_ASSERT(offsetTable != NULL);

  /* Init output arrays */
  FDKmemclear(channelType,    PCM_DMX_MAX_CHANNELS*sizeof(AUDIO_CHANNEL_TYPE));
  FDKmemclear(channelIndices, PCM_DMX_MAX_CHANNELS*sizeof(UCHAR));
  FDKmemset(offsetTable, 255, PCM_DMX_MAX_CHANNELS*sizeof(UCHAR));

  /* Extract the number of channels per group */
  numChInGrp[CH_GROUP_FRONT] =  chMode        & 0xF;
  numChInGrp[CH_GROUP_SIDE]  = (chMode >>  4) & 0xF;
  numChInGrp[CH_GROUP_REAR]  = (chMode >>  8) & 0xF;
  numChInGrp[CH_GROUP_LFE]   = (chMode >> 12) & 0xF;

  /* Summerize to get the total number of channels */
  for (grpIdx = 0; grpIdx < PCM_DMX_MAX_CHANNEL_GROUPS; grpIdx += 1) {
    numChannels += numChInGrp[grpIdx];
  }

  /* Get the appropriate channel map */
  pChannelMap = channelMapping[numChannels-1];

  /* Compose channel offset table */

  /* Non-symmetric channels */
  if (numChInGrp[CH_GROUP_FRONT] & 0x1) {
    /* Odd number of front channels -> we have a center channel.
       In MPEG-4 the center has the index 0. */
    offsetTable[CENTER_FRONT_CHANNEL] = pChannelMap[0];
    channelType[0] = ACT_FRONT;
    ch += 1;
  }

  for (grpIdx = 0; grpIdx < PCM_DMX_MAX_CHANNEL_GROUPS; grpIdx += 1) {
    AUDIO_CHANNEL_TYPE type;
    int chMapPos, maxChannels = 0;
    int chIdx = 0;

    switch (grpIdx) {
    case CH_GROUP_FRONT:
      type = ACT_FRONT;
      chMapPos = LEFT_FRONT_CHANNEL;
      maxChannels = 3;
      chIdx = numChInGrp[grpIdx] & 0x1;
      break;
    case CH_GROUP_SIDE:
      type = ACT_SIDE;
      chMapPos = LEFT_OUTSIDE_CHANNEL;
      maxChannels = 2;
      break;
    case CH_GROUP_REAR:
      type = ACT_BACK;
      chMapPos = LEFT_REAR_CHANNEL;
      maxChannels = 2;
      break;
    case CH_GROUP_LFE:
      type = ACT_LFE;
      chMapPos = LOW_FREQUENCY_CHANNEL;
      maxChannels = 1;
      break;
    default:
      break;
    }

    for ( ; (chIdx < numChInGrp[grpIdx]) && (chIdx < maxChannels); chIdx += 1) {
      offsetTable[chMapPos] = pChannelMap[ch];
      channelType[ch]    = type;
      channelIndices[ch] = chIdx;
      chMapPos += 1;
      ch += 1;
    }
  }
}


/** Open and initialize an instance of the PCM downmix module
 * @param [out] Pointer to a buffer receiving the handle of the new instance.
 * @returns Returns an error code.
 **/
PCMDMX_ERROR pcmDmx_Open (
    HANDLE_PCM_DOWNMIX *pSelf
  )
{
  HANDLE_PCM_DOWNMIX self;
  
  if (pSelf == NULL) {
    return (PCMDMX_INVALID_HANDLE);
  }

  *pSelf = NULL;

  self = (HANDLE_PCM_DOWNMIX) GetPcmDmxInstance( 0 );
  if (self == NULL) {
    return (PCMDMX_OUT_OF_MEMORY);
  }

  /* Reset the full instance */
  pcmDmx_Reset( self, PCMDMX_RESET_FULL );

  *pSelf = self;

  return (PCMDMX_OK);
}


/** Reset all static values like e.g. mixdown coefficients.
 * @param [in] Handle of PCM downmix module instance.
 * @param [in] Flags telling which parts of the module shall be reset.
 * @returns Returns an error code.
 **/
PCMDMX_ERROR pcmDmx_Reset (
    HANDLE_PCM_DOWNMIX  self,
    UINT                flags
  )
{
  if (self == NULL) { return (PCMDMX_INVALID_HANDLE); }

  if (flags & PCMDMX_RESET_PARAMS) {
    self->dualChannelMode   = STEREO_MODE;
    self->numOutputChannels = 0;
    self->applyProcessing   = 0;
    self->frameDelay        = 0;
    self->expiryFrame       = PCMDMX_DFLT_EXPIRY_FRAME;
  }

  if (flags & PCMDMX_RESET_BS_DATA) {
    int slot;
    for (slot = 0; slot <= PCM_DMX_MAX_DELAY_FRAMES; slot += 1) {
      self->dvbMixDownLevels[slot].centerMixLevelValue    = dvbDownmixFactors[2]; /* 0.707 */
      self->dvbMixDownLevels[slot].surroundMixLevelValue  = dvbDownmixFactors[0]; /* 1.000 */
      self->dvbMixDownLevels[slot].mixLevelsAvail = 0;

      self->mpegMixDownInfo[slot].mixdownAvailable = 0;
    }
    /* Reset expiry counter */
    self->expiryCount = 0;
  }

  return (PCMDMX_OK);
}


/** Set one parameter for one instance of the PCM downmix module.
 * @param [in] Handle of PCM downmix module instance.
 * @param [in] Parameter to be set.
 * @param [in] Parameter value.
 * @returns Returns an error code.
 **/
PCMDMX_ERROR pcmDmx_SetParam (
    HANDLE_PCM_DOWNMIX  self,
    PCMDMX_PARAM        param,
    UINT                value
  )
{
  switch (param)
  {
  case DMX_BS_DATA_EXPIRY_FRAME:
    if (self == NULL)
      return (PCMDMX_INVALID_HANDLE);
    self->expiryFrame = value;
    break;

  case DMX_BS_DATA_DELAY:
    if (value > PCM_DMX_MAX_DELAY_FRAMES) {
      return (PCMDMX_UNABLE_TO_SET_PARAM);
    }
    if (self == NULL) {
      return (PCMDMX_INVALID_HANDLE);
    }
    self->frameDelay = value;
    break;

  case NUMBER_OF_OUTPUT_CHANNELS:
    switch ((int)value) {  /* supported output channels */
    case -1: case 0: case 1: case 2:
    case 6: case 8:
      break;
    default:
      return (PCMDMX_UNABLE_TO_SET_PARAM);
    }
    if (self == NULL)
      return (PCMDMX_INVALID_HANDLE);
    if ((int)value > 0) {
      self->numOutputChannels = (int)value;
      self->applyProcessing = 1;
    } else {
      self->numOutputChannels = 0;
      self->applyProcessing = 0;
    }
    break;

  case DUAL_CHANNEL_DOWNMIX_MODE:
    switch ((DUAL_CHANNEL_MODE)value) {
    case STEREO_MODE:
    case CH1_MODE:
    case CH2_MODE:
    case MIXED_MODE:
      break;
    default:
      return (PCMDMX_UNABLE_TO_SET_PARAM);
    }
    if (self == NULL)
      return (PCMDMX_INVALID_HANDLE);
    self->dualChannelMode = (DUAL_CHANNEL_MODE)value;
    self->applyProcessing = 1;
    break;

  default:
    return (PCMDMX_UNKNOWN_PARAM);
  }

  return (PCMDMX_OK);
}


/** Read the ancillary data transported in DSEs of DVB streams with MPEG-4 content
 * @param [in] Handle of PCM downmix module instance.
 * @param [in] Pointer to ancillary data buffer.
 * @param [in] Size of ancillary data.
 * @param [in] Flag indicating wheter the DVB ancillary data is from an MPEG-1/2 or an MPEG-4 stream.
 * @returns Returns an error code.
 **/
PCMDMX_ERROR pcmDmx_ReadDvbAncData (
    HANDLE_PCM_DOWNMIX  self,
    UCHAR *pAncDataBuf,
    UINT   ancDataBytes,
    int    isMpeg2
  )
{
  DVB_MIXDOWN_LEVELS *pDownmixLevels = &self->dvbMixDownLevels[0];

  int   offset = (isMpeg2) ? 2 : 0;
  UCHAR ancDataStatus;

  if (self == NULL) { return (PCMDMX_INVALID_HANDLE); }

  /* sanity checks */
  if (pAncDataBuf == NULL || ancDataBytes < (UCHAR)(3+offset)) {
    return (PCMDMX_CORRUPT_ANC_DATA);
  }

  /* check sync word */
  if (pAncDataBuf[offset] != ANC_DATA_SYNC_BYTE) {
    return (PCMDMX_CORRUPT_ANC_DATA);
  }

  offset += 2;
  ancDataStatus = pAncDataBuf[offset++];

  if (isMpeg2) {
    /* skip advanced_dynamic_range_control */
    if (ancDataStatus & 0x80) offset += 3;
    /* skip dialog_normalization */
    if (ancDataStatus & 0x40) offset += 1;
    /* skip reproduction_level */
    if (ancDataStatus & 0x20) offset += 1;
  }
  else {
    /* check reserved bits */
    if (ancDataStatus & 0xE8) { return (PCMDMX_CORRUPT_ANC_DATA); }
  }

  /* downmix_levels_MPEGX */
  if (ancDataStatus & 0x10)
  {
    int   foundNewData = 0;
    UCHAR downmixData = pAncDataBuf[offset++];

    if (downmixData & 0x80) {  /* center_mix_level_on */
      pDownmixLevels->centerMixLevelValue =
        dvbDownmixFactors[(downmixData >> 4) & 0x07];
      foundNewData = 1;
    } else {
      pDownmixLevels->centerMixLevelValue = dvbDownmixFactors[0];
      if (downmixData & 0x70) { return (PCMDMX_CORRUPT_ANC_DATA); }
    }

    if (downmixData & 0x08) {  /* surround_mix_level_on */
      pDownmixLevels->surroundMixLevelValue =
        dvbDownmixFactors[downmixData & 0x07];
      foundNewData = 1;
    } else {
      pDownmixLevels->surroundMixLevelValue = dvbDownmixFactors[0];
      if (downmixData & 0x07) { return (PCMDMX_CORRUPT_ANC_DATA); }
    }

    pDownmixLevels->mixLevelsAvail = foundNewData;
  }

  /* Reset expiry counter */
  self->expiryCount = 0;

  return (PCMDMX_OK);
}

/** Set the matrix mixdown information extracted from the PCE of an AAC bitstream.
 *  Note: Call only if matrix_mixdown_idx_present is true.
 * @param [in] Handle of PCM downmix module instance.
 * @param [in] The 2 bit matrix mixdown index extracted from PCE.
 * @param [in] The pseudo surround enable flag extracted from PCE.
 * @returns Returns an error code.
 **/
PCMDMX_ERROR pcmDmx_SetMatrixMixdownFromPce (
    HANDLE_PCM_DOWNMIX  self,
    int                 matrixMixdownPresent,
    int                 matrixMixdownIdx,
    int                 pseudoSurroundEnable
  )
{
  MPEG_MIXDOWN_INFO *pMpegMixDownInfo;

  if (self == NULL) {
    return (PCMDMX_INVALID_HANDLE);
  }

  pMpegMixDownInfo = &self->mpegMixDownInfo[0];

  if (matrixMixdownPresent) {
    pMpegMixDownInfo->matrixMixdownIdx     = matrixMixdownIdx & 0x03;
    pMpegMixDownInfo->pseudoSurroundEnable = pseudoSurroundEnable;
  }

  pMpegMixDownInfo->mixdownAvailable = matrixMixdownPresent;
  /* Reset expiry counter */
  self->expiryCount = 0;

  return (PCMDMX_OK);
}


/** Apply down or up mixing.
 * @param [in]    Handle of PCM downmix module instance.
 * @param [inout] Pointer to time buffer. Depending on interface configuration, the content of pTimeData is ignored,
 *                and the internal QMF buffer will be used as input data source. Otherwise, the MPEG Surround processing is
 *                applied to the timesignal pTimeData. For both variants, the resulting MPEG Surround signal is written into pTimeData.
 * @param [in]    Pointer where the amount of output samples is returned into.
 * @param [inout] Pointer where the amount of output channels is returned into.
 * @param [in]    Flag which indicates if output time data are writtern interleaved or as subsequent blocks.
 * @param [inout] Array where the corresponding channel type for each output audio channel is stored into.
 * @param [inout] Array where the corresponding channel type index for each output audio channel is stored into.
 * @param [in]    Array containing the output channel mapping to be used (From MPEG PCE ordering to whatever is required).
 * @returns Returns an error code.
 **/
PCMDMX_ERROR pcmDmx_ApplyFrame (
        HANDLE_PCM_DOWNMIX      self,
        INT_PCM                *pPcmBuf,
        UINT                    frameSize,
        INT                    *nChannels,

        int                     fInterleaved,
        AUDIO_CHANNEL_TYPE      channelType[],
        UCHAR                   channelIndices[],
        const UCHAR             channelMapping[][8]
  )
{
  PCMDMX_ERROR  errorStatus = PCMDMX_OK;
  DUAL_CHANNEL_MODE  dualChannelMode;
  PCM_DMX_CHANNEL_MODE  inChMode;
  int   numOutChannels;
  int   numInChannels = *nChannels;
  int   slot;
  UCHAR inOffsetTable[PCM_DMX_MAX_CHANNELS];

  MPEG_MIXDOWN_INFO   mpegMixDownInfo;
  DVB_MIXDOWN_LEVELS  dvbMixDownLevels;

  if (self == NULL) { return (PCMDMX_INVALID_HANDLE); }

  if ( (self->expiryFrame > 0)
    && (++self->expiryCount > self->expiryFrame) )
  { /* The metadata read from bitstream is too old. */
    errorStatus = pcmDmx_Reset(self, PCMDMX_RESET_BS_DATA);
  }

  FDKmemcpy(&mpegMixDownInfo, &self->mpegMixDownInfo[self->frameDelay], sizeof(MPEG_MIXDOWN_INFO));
  /* Maintain delay line */
  for (slot = self->frameDelay; slot > 0; slot -= 1) {
    FDKmemcpy(&self->mpegMixDownInfo[slot], &self->mpegMixDownInfo[slot-1], sizeof(MPEG_MIXDOWN_INFO));
  }
  FDKmemcpy(&dvbMixDownLevels, &self->dvbMixDownLevels[self->frameDelay], sizeof(DVB_MIXDOWN_LEVELS));
  /* Maintain delay line */
  for (slot = self->frameDelay; slot > 0; slot -= 1) {
    FDKmemcpy(&self->dvbMixDownLevels[slot], &self->dvbMixDownLevels[slot-1], sizeof(DVB_MIXDOWN_LEVELS));
  }

  if (self->applyProcessing == 0) { return (errorStatus); }

  if (pPcmBuf == NULL)     { return (PCMDMX_INVALID_ARGUMENT); }
  if (frameSize == 0)      { return (PCMDMX_INVALID_ARGUMENT); }
  if (numInChannels == 0)  { return (PCMDMX_INVALID_ARGUMENT); }

  if (self->numOutputChannels <= 0) {
    numOutChannels = numInChannels;
  } else {
    numOutChannels = self->numOutputChannels;
  }
  dualChannelMode = self->dualChannelMode;

  /* Analyse input channel configuration and get channel offset
   * table that can be accessed with the fixed channel labels. */
  inChMode = getChannelMode(
                   numInChannels,
                   channelType,
                   channelIndices,
                   inOffsetTable
                 );
  if (inChMode == CH_MODE_UNDEFINED) {
    /* We don't need to restore because the channel
       configuration has not been changed. Just exit. */
    return (PCMDMX_INVALID_CH_CONFIG);
  }

  /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  if ( numInChannels > numOutChannels )
  { /* Apply downmix */
    INT_PCM  *pInCF, *pInLF, *pInRF, *pInLO, *pInRO, *pInLR, *pInRR, *pOutL, *pOutR;
    FIXP_SGL  flev, clev, slev;

    UINT   sample;
    int    inStride, outStride, offset;
    int    useGuidedDownMix = 0;
    UCHAR  outOffsetTable[PCM_DMX_MAX_CHANNELS];

    /* Set I/O strides and offsets */
    if (fInterleaved) {
      inStride  = numInChannels;
      outStride = TWO_CHANNEL;   /* The output of STAGE ONE is always STEREO !!!
                                    STAGE TWO creates a downmix to mono if required. */
      offset = 1;                /* Channel specific offset factor */
    } else {
      inStride  = 1;
      outStride = 1;
      offset = frameSize;        /* Channel specific offset factor */
    }

    /* Get channel description and channel mapping for this
     * stages number of output channels (always STEREO). */
    getChannelDescription(
            CH_MODE_2_0_0_0,
            channelMapping,
            channelType,
            channelIndices,
            outOffsetTable
           );
    /* Now there is no way back because we modified the channel configuration! */

    /* Set channel pointer for input */
    pInCF = &pPcmBuf[inOffsetTable[CENTER_FRONT_CHANNEL]*offset];
    pInLF = &pPcmBuf[inOffsetTable[LEFT_FRONT_CHANNEL]*offset];
    pInRF = &pPcmBuf[inOffsetTable[RIGHT_FRONT_CHANNEL]*offset];
    pInLO = &pPcmBuf[inOffsetTable[LEFT_OUTSIDE_CHANNEL]*offset];
    pInRO = &pPcmBuf[inOffsetTable[RIGHT_OUTSIDE_CHANNEL]*offset];
    pInLR = &pPcmBuf[inOffsetTable[LEFT_REAR_CHANNEL]*offset];
    pInRR = &pPcmBuf[inOffsetTable[RIGHT_REAR_CHANNEL]*offset];

    /* Set channel pointer for output
       Caution: Different channel mapping compared to input */
    pOutL = &pPcmBuf[outOffsetTable[LEFT_FRONT_CHANNEL]*offset];    /* LEFT_FRONT_CHANNEL  */
    pOutR = &pPcmBuf[outOffsetTable[RIGHT_FRONT_CHANNEL]*offset];   /* RIGHT_FRONT_CHANNEL */

    /* Set downmix levels: */
    flev = ATTENUATION_FACTOR_1;    /* 0.707 */
    clev = ATTENUATION_FACTOR_1;    /* 0.707 */
    slev = ATTENUATION_FACTOR_1;    /* 0.707 */

    if ( dvbMixDownLevels.mixLevelsAvail ) {
      clev = dvbMixDownLevels.centerMixLevelValue;
      slev = dvbMixDownLevels.surroundMixLevelValue;
      useGuidedDownMix = 1;
    }

    /* FIRST STAGE:
         Always downmix to 2 channel output: */
    switch ( inChMode )
    {
    case CH_MODE_2_0_0_0:
    case CH_MODE_2_0_0_1: 
      /* 2/0 input: */
      switch (dualChannelMode)
      {
      case CH1_MODE:  /* L' = 0.707 * Ch1;  R' = 0.707 * Ch1 */
        for (sample = 0; sample < frameSize; sample++) {
          *pOutL = *pOutR =
            (INT_PCM)SATURATE_RIGHT_SHIFT(fMult((FIXP_PCM)*pInLF, flev), DFRACT_BITS-SAMPLE_BITS, SAMPLE_BITS);

          pInLF += inStride;
          pOutL += outStride; pOutR += outStride;
        }
        break;

      case CH2_MODE:  /* L' = 0.707 * Ch2;  R' = 0.707 * Ch2 */
        for (sample = 0; sample < frameSize; sample++) {
          *pOutL = *pOutR =
            (INT_PCM)SATURATE_RIGHT_SHIFT(fMult((FIXP_PCM)*pInRF, flev), DFRACT_BITS-SAMPLE_BITS, SAMPLE_BITS);

          pInRF += inStride;
          pOutL += outStride; pOutR += outStride;
        }
        break;
      case MIXED_MODE:  /* L' = 0.5*Ch1 + 0.5*Ch2;  R' = 0.5*Ch1 + 0.5*Ch2 */
        for (sample = 0; sample < frameSize; sample++) {
          *pOutL = *pOutR = (*pInLF >> 1) + (*pInRF >> 1);

          pInLF += inStride;  pInRF += inStride;
          pOutL += outStride; pOutR += outStride;
        }
        break;
      default:
      case STEREO_MODE:
        /* nothing to do */
        break;
      }
      break;

    case CH_MODE_3_0_0_0:
      /* 3/0 input:  L' = L + 0.707*C;  R' = R + 0.707*C; */
      for (sample = 0; sample < frameSize; sample++)
      {
        FIXP_DBL tCF = fMultDiv2((FIXP_PCM)*pInCF, clev);
#if (SAMPLE_BITS == 32)
        /* left channel */
        *pOutL = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>1)+tCF, 1, SAMPLE_BITS);
        /* right channel */
        *pOutR = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>1)+tCF, 1, SAMPLE_BITS);
#else
        /* left channel */
        *pOutL = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>1)+tCF, DFRACT_BITS-SAMPLE_BITS-1, SAMPLE_BITS);
        /* right channel */
        *pOutR = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>1)+tCF, DFRACT_BITS-SAMPLE_BITS-1, SAMPLE_BITS);
#endif
        pInLF += inStride;  pInRF += inStride;  pInCF  += inStride;
        pOutL += outStride; pOutR += outStride;
      }
      break;

    /* 2/1 input: not supported!
    case CH_MODE_2_0_1_0: */

    case CH_MODE_3_0_1_0:
      if (useGuidedDownMix) {
        /* 3/1 input:  L' = L + clev*C + 0.707*slev*S;  R' = R + clev*C + 0.707*slev*S; */
        slev = FX_DBL2FX_SGL(fMult(flev, slev));  /* 0.707*slef */

        for (sample = 0; sample < frameSize; sample++)
        {
          FIXP_DBL tCF = fMultDiv2((FIXP_PCM)*pInCF, clev) >> 1;
          FIXP_DBL tLR = fMultDiv2((FIXP_PCM)*pInLR, slev) >> 1;
#if (SAMPLE_BITS == 32)
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>2)+tCF+tLR, 2, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>2)+tCF+tLR, 2, SAMPLE_BITS);
#else
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>2)+tCF-tLR, DFRACT_BITS-SAMPLE_BITS-2, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>2)+tCF+tLR, DFRACT_BITS-SAMPLE_BITS-2, SAMPLE_BITS);
#endif
          pInLF += inStride;  pInRF += inStride;  pInCF  += inStride;  pInLR  += inStride;
          pOutL += outStride; pOutR += outStride;
        }
      } else {
        /* 3/1 input:  L' = L + 0.707*C - 0.707*S;  R' = R + 0.707*C + 0.707*S */
        for (sample = 0; sample < frameSize; sample++)
        {
          FIXP_DBL tCF = fMultDiv2((FIXP_PCM)*pInCF, clev) >> 1;
          FIXP_DBL tLR = fMultDiv2((FIXP_PCM)*pInLR, slev) >> 1;
#if (SAMPLE_BITS == 32)
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>2)+tCF-tLR, 2, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>2)+tCF+tLR, 2, SAMPLE_BITS);
#else
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>2)+tCF-tLR, DFRACT_BITS-SAMPLE_BITS-2, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>2)+tCF+tLR, DFRACT_BITS-SAMPLE_BITS-2, SAMPLE_BITS);
#endif
          pInLF += inStride;  pInRF += inStride;  pInCF  += inStride;  pInLR  += inStride;
          pOutL += outStride; pOutR += outStride;
        }
      }
      break;

    /* 2/2 input: not supported!
    case CH_MODE_2_0_2_0: */

    case CH_MODE_3_0_2_0:   /* 5.0ch input */
    case CH_MODE_3_0_2_1:   /* 5.1ch input */
      if (useGuidedDownMix) {
        /* 3/2 input:  L' = L + clev*C + slev*Ls;  R' = R + clev*C + slev*Rs; */
        for (sample = 0; sample < frameSize; sample++)
        {
          FIXP_DBL tCF = fMultDiv2((FIXP_PCM)*pInCF, clev) >> 1;
          FIXP_DBL tLR = fMultDiv2((FIXP_PCM)*pInLR, slev) >> 1;
          FIXP_DBL tRR = fMultDiv2((FIXP_PCM)*pInRR, slev) >> 1;
#if (SAMPLE_BITS == 32)
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>2)+tCF+tLR, 2, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>2)+tCF+tRR, 2, SAMPLE_BITS);
#else
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>2)+tCF+tLR, DFRACT_BITS-SAMPLE_BITS-2, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>2)+tCF+tRR, DFRACT_BITS-SAMPLE_BITS-2, SAMPLE_BITS);
#endif
          pInLF += inStride;  pInRF += inStride;  pInCF  += inStride;  pInLR  += inStride;  pInRR  += inStride;
          pOutL += outStride; pOutR += outStride;
        }
      }
      else if (mpegMixDownInfo.mixdownAvailable) {
        /* 3/2 input: L' = (1.707+A)^-1 * [L+0.707*C+A*Ls]; R'= (1.707+A)^-1 * [R+0.707*C+A*Rs]; */
        FIXP_SGL mtrxMixDwnCoef    = mpegMixDownIdx2Coef[mpegMixDownInfo.matrixMixdownIdx];
        FIXP_SGL mtrxMixDwnPreFact = mpegMixDownIdx2PreFact[mpegMixDownInfo.matrixMixdownIdx];
        clev = FX_DBL2FX_SGL(fMult(mtrxMixDwnPreFact, flev /* 0.707 */));
        flev = mtrxMixDwnPreFact;
        slev = FX_DBL2FX_SGL(fMult(mtrxMixDwnPreFact, mtrxMixDwnCoef));

        for (sample = 0; sample < frameSize; sample++)
        {
          FIXP_DBL tCF = fMultDiv2((FIXP_PCM)*pInCF, clev);
          FIXP_DBL tLF = fMultDiv2((FIXP_PCM)*pInLF, flev);
          FIXP_DBL tRF = fMultDiv2((FIXP_PCM)*pInRF, flev);
          FIXP_DBL tLR = fMultDiv2((FIXP_PCM)*pInLR, slev);
          FIXP_DBL tRR = fMultDiv2((FIXP_PCM)*pInRR, slev);

#if (SAMPLE_BITS == 32)
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_LEFT_SHIFT(tLF+tCF+tLR, 1, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_LEFT_SHIFT(tRF+tCF+tRR, 1, SAMPLE_BITS);
#else
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_RIGHT_SHIFT(tLF+tCF+tLR, DFRACT_BITS-SAMPLE_BITS-1, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_RIGHT_SHIFT(tRF+tCF+tRR, DFRACT_BITS-SAMPLE_BITS-1, SAMPLE_BITS);
#endif

          pInLF += inStride;  pInRF += inStride;  pInCF  += inStride;  pInLR  += inStride;  pInRR  += inStride;
          pOutL += outStride; pOutR += outStride;
        }
      }
      else {
        /* 3/2 input:  L' = L + 0.707*C - 0.707*Ls - 0.707*Rs;  R' = R + 0.707*C + 0.707*Ls + 0.707*Rs */
        for (sample = 0; sample < frameSize; sample++)
        {
          FIXP_DBL tCF = fMultDiv2((FIXP_PCM)*pInCF, clev) >> 2;
          FIXP_DBL tLR = fMultDiv2((FIXP_PCM)*pInLR, slev) >> 2;
          FIXP_DBL tRR = fMultDiv2((FIXP_PCM)*pInRR, slev) >> 2;
#if (SAMPLE_BITS == 32)
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>3)+tCF-tLR-tRR, 3, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_LEFT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>3)+tCF+tLR+tRR, 3, SAMPLE_BITS);
#else
          /* left channel */
          *pOutL = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInLF)>>3)+tCF-tLR-tRR, DFRACT_BITS-SAMPLE_BITS-3, SAMPLE_BITS);
          /* right channel */
          *pOutR = (INT_PCM)SATURATE_RIGHT_SHIFT((FX_PCM2FX_DBL((FIXP_PCM)*pInRF)>>3)+tCF+tLR+tRR, DFRACT_BITS-SAMPLE_BITS-3, SAMPLE_BITS);
#endif
          pInLF += inStride;  pInRF += inStride;  pInCF  += inStride;  pInLR  += inStride;  pInRR  += inStride;
          pOutL += outStride; pOutR += outStride;
        }
      }
      break;

    default:
      errorStatus = PCMDMX_INVALID_MODE;
      break;
    }

    /* SECOND STAGE:
         If desired create a mono donwmix:
         Note: Input are always two channels! */
    if (numOutChannels == 1)
    {
      INT_PCM *pOutC;
      FIXP_SGL mlev;

      if (useGuidedDownMix) mlev = FL2FXCONST_SGL(1.0f); else mlev = flev;

      /* Output of STAGE ONE = Input of STAGE TWO */
      FDKmemcpy(inOffsetTable, outOffsetTable, PCM_DMX_MAX_CHANNELS*sizeof(UCHAR));

      /* Set I/O strides and offsets */
      inStride  = outStride;          /* output from STAGE ONE */
      outStride = numOutChannels;     /* final output */

      /* Get channel description and channel mapping for this
       * stages number of output channels (always MONO). */
      getChannelDescription(
              CH_MODE_1_0_0_0,
              channelMapping,
              channelType,
              channelIndices,
              outOffsetTable
             );

      /* Set input channel pointer. */
      pInLF = &pPcmBuf[inOffsetTable[LEFT_FRONT_CHANNEL]*offset];
      pInRF = &pPcmBuf[inOffsetTable[RIGHT_FRONT_CHANNEL]*offset];

      /* Set output channel pointer */
      pOutC = &pPcmBuf[outOffsetTable[CENTER_FRONT_CHANNEL]*offset];

      /* C' = 0.707*L + 0.707*R */
      for (sample = 0; sample < frameSize; sample++) {
#if (SAMPLE_BITS == 32)
        *pOutC =
          (INT_PCM)SATURATE_LEFT_SHIFT(fMultDiv2((FIXP_PCM)*pInLF,mlev)+fMultDiv2((FIXP_PCM)*pInRF,mlev), 1, SAMPLE_BITS);
#else
        *pOutC =
          (INT_PCM)SATURATE_RIGHT_SHIFT(fMultDiv2((FIXP_PCM)*pInLF,mlev)+fMultDiv2((FIXP_PCM)*pInRF,mlev), DFRACT_BITS-SAMPLE_BITS-1, SAMPLE_BITS);
#endif

        pInLF += inStride; pInRF += inStride;
        pOutC += 1;
      }
      /* Finished STAGE TWO */
    }

    /* Update the number of output channels */
    *nChannels = self->numOutputChannels;

  } /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
  else
  if ( numInChannels == numOutChannels )
  {
    /* Don't need to change the channel description here */

    switch (numInChannels)
    {
    case 2:
      { /* Set up channel pointer */
        INT_PCM *pInLF, *pInRF, *pOutL, *pOutR;
        FIXP_SGL flev;

        UINT sample;
        int inStride, outStride, offset;

        if (fInterleaved) {
          inStride  = numInChannels;
          outStride = 2;  /* fixed !!! (below stereo is donwmixed to mono if required */
          offset = 1; /* Channel specific offset factor */
        } else {
          inStride  = 1;
          outStride = 1;
          offset = frameSize;  /* Channel specific offset factor */
        }

        /* Set input channel pointer */
        pInLF = &pPcmBuf[inOffsetTable[LEFT_FRONT_CHANNEL]*offset];
        pInRF = &pPcmBuf[inOffsetTable[RIGHT_FRONT_CHANNEL]*offset];

        /* Set output channel pointer (same as input) */
        pOutL  =  pInLF;
        pOutR  =  pInRF;

        /* Set downmix levels: */
        flev = ATTENUATION_FACTOR_1;    /* 0.707 */
        /* 2/0 input: */
        switch (dualChannelMode)
        {
        case CH1_MODE:  /* L' = 0.707 * Ch1;  R' = 0.707 * Ch1 */
          for (sample = 0; sample < frameSize; sample++) {
            *pOutL = *pOutR =
              (INT_PCM)SATURATE_RIGHT_SHIFT(fMult((FIXP_PCM)*pInLF, flev), DFRACT_BITS-SAMPLE_BITS, SAMPLE_BITS);

            pInLF += inStride;
            pOutL += outStride; pOutR += outStride;
          }
          break;
        case CH2_MODE:  /* L' = 0.707 * Ch2;  R' = 0.707 * Ch2 */
          for (sample = 0; sample < frameSize; sample++) {
            *pOutL = *pOutR =
              (INT_PCM)SATURATE_RIGHT_SHIFT(fMult((FIXP_PCM)*pInRF, flev), DFRACT_BITS-SAMPLE_BITS, SAMPLE_BITS);

            pInRF += inStride;
            pOutL += outStride; pOutR += outStride;
          }
          break;
        case MIXED_MODE:  /* L' = 0.5*Ch1 + 0.5*Ch2;  R' = 0.5*Ch1 + 0.5*Ch2 */
          for (sample = 0; sample < frameSize; sample++) {
            *pOutL = *pOutR = (*pInLF >> 1) + (*pInRF >> 1);

            pInLF += inStride;  pInRF += inStride;
            pOutL += outStride; pOutR += outStride;
          }
          break;
        default:
        case STEREO_MODE:
          /* nothing to do */
          break;
        }
      }
      break;

    default:
      /* nothing to do */
      break;
    }
  }

  return (errorStatus);
}


/** Close an instance of the PCM downmix module.
 * @param [inout] Pointer to a buffer containing the handle of the instance.
 * @returns Returns an error code.
 **/
PCMDMX_ERROR pcmDmx_Close (
    HANDLE_PCM_DOWNMIX *pSelf
  )
{
  if (pSelf == NULL) {
    return (PCMDMX_INVALID_HANDLE);
  }

  FreePcmDmxInstance( pSelf );
  *pSelf = NULL;

  return (PCMDMX_OK);
}


/** Get library info for this module.
 * @param [out] Pointer to an allocated LIB_INFO structure.
 * @returns Returns an error code.
 */
PCMDMX_ERROR pcmDmx_GetLibInfo( LIB_INFO *info )
{
  int i;

  if (info == NULL) {
    return PCMDMX_INVALID_ARGUMENT;
  }

  /* Search for next free tab */
  for (i = 0; i < FDK_MODULE_LAST; i++) {
    if (info[i].module_id == FDK_NONE) break;
  }
  if (i == FDK_MODULE_LAST) {
    return PCMDMX_UNKNOWN;
  }
  info += i;

  /* Add the library info */
  info->module_id  = FDK_PCMDMX;
  info->version    = LIB_VERSION(PCMDMX_LIB_VL0, PCMDMX_LIB_VL1, PCMDMX_LIB_VL2);
  LIB_VERSION_STRING(info);
  info->build_date = PCMDMX_LIB_BUILD_DATE;
  info->build_time = PCMDMX_LIB_BUILD_TIME;
  info->title      = PCMDMX_LIB_TITLE;

  /* Set flags */
  info->flags = 0
      | CAPF_DMX_BLIND   /* At least blind downmixing is possible */
      | CAPF_DMX_PCE     /* Guided downmix with data from MPEG-2/4 Program Config Elements (PCE). */
      | CAPF_DMX_DVB     /* Guided downmix with data from DVB ancillary data fields. */
      ;

  return PCMDMX_OK;
}