Fraunhofer AAC codec.

License boilerplate update to follow.

Change-Id: I2810460c11a58b6d148d84673cc031f3685e79b5

1 files changed, 794 insertions, 0 deletions

diff --git a/libSBRdec/src/env_dec.cpp b/libSBRdec/src/env_dec.cpp
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+/****************************************************************************
+
+                     (C) Copyright Fraunhofer IIS (2004)
+                               All Rights Reserved
+
+    Please be advised that this software and/or program delivery is
+    Confidential Information of Fraunhofer and subject to and covered by the
+
+    Fraunhofer IIS Software Evaluation Agreement
+    between Google Inc. and  Fraunhofer
+    effective and in full force since March 1, 2012.
+
+    You may use this software and/or program only under the terms and
+    conditions described in the above mentioned Fraunhofer IIS Software
+    Evaluation Agreement. Any other and/or further use requires a separate agreement.
+
+
+   This software and/or program is protected by copyright law and international
+   treaties. Any reproduction or distribution of this software and/or program,
+   or any portion of it, may result in severe civil and criminal penalties, and
+   will be prosecuted to the maximum extent possible under law.
+
+ $Id$
+
+****************************************************************************/
+/*!
+  \file
+  \brief  envelope decoding $Revision: 36841 $
+  This module provides envelope decoding and error concealment algorithms. The main
+  entry point is decodeSbrData().
+
+  \sa decodeSbrData(),\ref documentationOverview
+*/
+
+#include "env_dec.h"
+
+#include "env_extr.h"
+#include "transcendent.h"
+
+#include "genericStds.h"
+
+
+static void decodeEnvelope (HANDLE_SBR_HEADER_DATA hHeaderData,
+                            HANDLE_SBR_FRAME_DATA h_sbr_data,
+                            HANDLE_SBR_PREV_FRAME_DATA h_prev_data,
+                            HANDLE_SBR_PREV_FRAME_DATA h_prev_data_otherChannel);
+static void sbr_envelope_unmapping (HANDLE_SBR_HEADER_DATA hHeaderData,
+                                    HANDLE_SBR_FRAME_DATA h_data_left,
+                                    HANDLE_SBR_FRAME_DATA h_data_right);
+static void requantizeEnvelopeData (HANDLE_SBR_FRAME_DATA h_sbr_data,
+                                    int ampResolution);
+static void deltaToLinearPcmEnvelopeDecoding (HANDLE_SBR_HEADER_DATA hHeaderData,
+                                              HANDLE_SBR_FRAME_DATA h_sbr_data,
+                                              HANDLE_SBR_PREV_FRAME_DATA h_prev_data);
+static void decodeNoiseFloorlevels (HANDLE_SBR_HEADER_DATA hHeaderData,
+                                    HANDLE_SBR_FRAME_DATA h_sbr_data,
+                                    HANDLE_SBR_PREV_FRAME_DATA h_prev_data);
+static void timeCompensateFirstEnvelope (HANDLE_SBR_HEADER_DATA hHeaderData,
+                                         HANDLE_SBR_FRAME_DATA h_sbr_data,
+                                         HANDLE_SBR_PREV_FRAME_DATA h_prev_data);
+static int checkEnvelopeData (HANDLE_SBR_HEADER_DATA hHeaderData,
+                              HANDLE_SBR_FRAME_DATA h_sbr_data,
+                              HANDLE_SBR_PREV_FRAME_DATA h_prev_data);
+
+
+
+#define SBR_ENERGY_PAN_OFFSET   (12 << ENV_EXP_FRACT)
+#define SBR_MAX_ENERGY          (35 << ENV_EXP_FRACT)
+
+#define DECAY                   ( 1 << ENV_EXP_FRACT)
+
+#if ENV_EXP_FRACT
+#define DECAY_COUPLING          ( 1 << (ENV_EXP_FRACT-1) ) /*!< corresponds to a value of 0.5 */
+#else
+#define DECAY_COUPLING            1  /*!< If the energy data is not shifted, use 1 instead of 0.5 */
+#endif
+
+
+/*!
+  \brief  Convert table index
+*/
+static int indexLow2High(int offset, /*!< mapping factor */
+                         int index,  /*!< index to scalefactor band */
+                         int res)    /*!< frequency resolution */
+{
+  if(res == 0)
+  {
+    if (offset >= 0)
+    {
+        if (index < offset)
+          return(index);
+        else
+          return(2*index - offset);
+    }
+    else
+    {
+        offset = -offset;
+        if (index < offset)
+          return(2*index+index);
+        else
+          return(2*index + offset);
+    }
+  }
+  else
+    return(index);
+}
+
+
+/*!
+  \brief  Update previous envelope value for delta-coding
+
+  The current envelope values needs to be stored for delta-coding
+  in the next frame.  The stored envelope is always represented with
+  the high frequency resolution.  If the current envelope uses the
+  low frequency resolution, the energy value will be mapped to the
+  corresponding high-res bands.
+*/
+static void mapLowResEnergyVal(FIXP_SGL currVal,  /*!< current energy value */
+                               FIXP_SGL* prevData,/*!< pointer to previous data vector */
+                               int offset,      /*!< mapping factor */
+                               int index,       /*!< index to scalefactor band */
+                               int res)         /*!< frequeny resolution */
+{
+  if(res == 0)
+  {
+    if (offset >= 0)
+    {
+        if(index < offset)
+            prevData[index] = currVal;
+        else
+        {
+            prevData[2*index - offset] = currVal;
+            prevData[2*index+1 - offset] = currVal;
+        }
+    }
+    else
+    {
+        offset = -offset;
+        if (index < offset)
+        {
+            prevData[3*index] = currVal;
+            prevData[3*index+1] = currVal;
+            prevData[3*index+2] = currVal;
+        }
+        else
+        {
+            prevData[2*index + offset] = currVal;
+            prevData[2*index + 1 + offset] = currVal;
+        }
+    }
+  }
+  else
+    prevData[index] = currVal;
+}
+
+
+
+/*!
+  \brief    Convert raw envelope and noisefloor data to energy levels
+
+  This function is being called by sbrDecoder_ParseElement() and provides two important algorithms:
+
+  First the function decodes envelopes and noise floor levels as described in requantizeEnvelopeData()
+  and sbr_envelope_unmapping(). The function also implements concealment algorithms in case there are errors
+  within the sbr data. For both operations fractional arithmetic is used.
+  Therefore you might encounter different output values on your target
+  system compared to the reference implementation.
+*/
+void
+decodeSbrData (HANDLE_SBR_HEADER_DATA hHeaderData,          /*!< Static control data */
+               HANDLE_SBR_FRAME_DATA h_data_left,           /*!< pointer to left channel frame data */
+               HANDLE_SBR_PREV_FRAME_DATA h_prev_data_left, /*!< pointer to left channel previous frame data */
+               HANDLE_SBR_FRAME_DATA h_data_right,          /*!< pointer to right channel frame data */
+               HANDLE_SBR_PREV_FRAME_DATA h_prev_data_right)/*!< pointer to right channel previous frame data */
+{
+  FIXP_SGL tempSfbNrgPrev[MAX_FREQ_COEFFS];
+  int errLeft;
+
+  /* Save previous energy values to be able to reuse them later for concealment. */
+  FDKmemcpy (tempSfbNrgPrev, h_prev_data_left->sfb_nrg_prev, MAX_FREQ_COEFFS * sizeof(FIXP_SGL));
+
+  decodeEnvelope (hHeaderData, h_data_left, h_prev_data_left, h_prev_data_right);
+  decodeNoiseFloorlevels (hHeaderData, h_data_left, h_prev_data_left);
+
+  if(h_data_right != NULL) {
+    errLeft = hHeaderData->frameErrorFlag;
+    decodeEnvelope (hHeaderData, h_data_right, h_prev_data_right, h_prev_data_left);
+    decodeNoiseFloorlevels (hHeaderData, h_data_right, h_prev_data_right);
+
+    if (!errLeft && hHeaderData->frameErrorFlag) {
+      /* If an error occurs in the right channel where the left channel seemed ok,
+         we apply concealment also on the left channel. This ensures that the coupling
+         modes of both channels match and that we have the same number of envelopes in
+         coupling mode.
+         However, as the left channel has already been processed before, the resulting
+         energy levels are not the same as if the left channel had been concealed
+         during the first call of decodeEnvelope().
+      */
+      /* Restore previous energy values for concealment, because the values have been
+         overwritten by the first call of decodeEnvelope(). */
+      FDKmemcpy (h_prev_data_left->sfb_nrg_prev, tempSfbNrgPrev, MAX_FREQ_COEFFS * sizeof(FIXP_SGL));
+      /* Do concealment */
+      decodeEnvelope (hHeaderData, h_data_left, h_prev_data_left, h_prev_data_right);
+    }
+
+    if (h_data_left->coupling) {
+      sbr_envelope_unmapping (hHeaderData, h_data_left, h_data_right);
+    }
+  }
+
+  /* Display the data for debugging: */
+}
+
+
+/*!
+  \brief   Convert from coupled channels to independent L/R data
+*/
+static void
+sbr_envelope_unmapping (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */
+                        HANDLE_SBR_FRAME_DATA h_data_left,  /*!< pointer to left channel */
+                        HANDLE_SBR_FRAME_DATA h_data_right) /*!< pointer to right channel */
+{
+  int i;
+  FIXP_SGL tempL_m, tempR_m, tempRplus1_m, newL_m, newR_m;
+  SCHAR   tempL_e, tempR_e, tempRplus1_e, newL_e, newR_e;
+
+
+  /* 1. Unmap (already dequantized) coupled envelope energies */
+
+  for (i = 0; i < h_data_left->nScaleFactors; i++) {
+    tempR_m = (FIXP_SGL)((LONG)h_data_right->iEnvelope[i] & MASK_M);
+    tempR_e = (SCHAR)((LONG)h_data_right->iEnvelope[i] & MASK_E);
+
+    tempR_e -= (18 + NRG_EXP_OFFSET);  /* -18 = ld(UNMAPPING_SCALE / h_data_right->nChannels) */
+    tempL_m = (FIXP_SGL)((LONG)h_data_left->iEnvelope[i] & MASK_M);
+    tempL_e = (SCHAR)((LONG)h_data_left->iEnvelope[i] & MASK_E);
+
+    tempL_e -= NRG_EXP_OFFSET;
+
+    /* Calculate tempRight+1 */
+    FDK_add_MantExp( tempR_m, tempR_e,
+                     FL2FXCONST_SGL(0.5f), 1,  /* 1.0 */
+                     &tempRplus1_m, &tempRplus1_e);
+
+    FDK_divide_MantExp( tempL_m, tempL_e+1,  /*  2 * tempLeft */
+                       tempRplus1_m, tempRplus1_e,
+                       &newR_m, &newR_e );
+
+    if (newR_m >= ((FIXP_SGL)MAXVAL_SGL - ROUNDING)) {
+      newR_m >>= 1;
+      newR_e += 1;
+    }
+
+    newL_m = FX_DBL2FX_SGL(fMult(tempR_m,newR_m));
+    newL_e = tempR_e + newR_e;
+
+    h_data_right->iEnvelope[i] = ((FIXP_SGL)((SHORT)(FIXP_SGL)(newR_m + ROUNDING) & MASK_M)) +
+                                  (FIXP_SGL)((SHORT)(FIXP_SGL)(newR_e + NRG_EXP_OFFSET) & MASK_E);
+    h_data_left->iEnvelope[i] =  ((FIXP_SGL)((SHORT)(FIXP_SGL)(newL_m + ROUNDING) & MASK_M)) +
+                                  (FIXP_SGL)((SHORT)(FIXP_SGL)(newL_e + NRG_EXP_OFFSET) & MASK_E);
+  }
+
+  /* 2. Dequantize and unmap coupled noise floor levels */
+
+  for (i = 0; i < hHeaderData->freqBandData.nNfb * h_data_left->frameInfo.nNoiseEnvelopes; i++) {
+
+    tempL_e = (SCHAR)(6 - (LONG)h_data_left->sbrNoiseFloorLevel[i]);
+    tempR_e = (SCHAR)((LONG)h_data_right->sbrNoiseFloorLevel[i] - 12) /*SBR_ENERGY_PAN_OFFSET*/;
+
+    /* Calculate tempR+1 */
+    FDK_add_MantExp( FL2FXCONST_SGL(0.5f), 1+tempR_e, /* tempR */
+                     FL2FXCONST_SGL(0.5f), 1,         /*  1.0  */
+                     &tempRplus1_m, &tempRplus1_e);
+
+    /* Calculate 2*tempLeft/(tempR+1) */
+    FDK_divide_MantExp( FL2FXCONST_SGL(0.5f), tempL_e+2,  /*  2 * tempLeft */
+                       tempRplus1_m, tempRplus1_e,
+                       &newR_m, &newR_e );
+
+    /* if (newR_m >= ((FIXP_SGL)MAXVAL_SGL - ROUNDING)) {
+      newR_m >>= 1;
+      newR_e += 1;
+    } */
+
+    /* L = tempR * R */
+    newL_m = newR_m;
+    newL_e = newR_e + tempR_e;
+    h_data_right->sbrNoiseFloorLevel[i] = ((FIXP_SGL)((SHORT)(FIXP_SGL)(newR_m + ROUNDING) & MASK_M)) +
+                                           (FIXP_SGL)((SHORT)(FIXP_SGL)(newR_e + NOISE_EXP_OFFSET) & MASK_E);
+    h_data_left->sbrNoiseFloorLevel[i] =  ((FIXP_SGL)((SHORT)(FIXP_SGL)(newL_m + ROUNDING) & MASK_M)) +
+                                           (FIXP_SGL)((SHORT)(FIXP_SGL)(newL_e + NOISE_EXP_OFFSET) & MASK_E);
+  }
+}
+
+
+/*!
+  \brief    Simple alternative to the real SBR concealment
+
+  If the real frameInfo is not available due to a frame loss, a replacement will
+  be constructed with 1 envelope spanning the whole frame (FIX-FIX).
+  The delta-coded energies are set to negative values, resulting in a fade-down.
+  In case of coupling, the balance-channel will move towards the center.
+*/
+static void
+leanSbrConcealment(HANDLE_SBR_HEADER_DATA hHeaderData,     /*!< Static control data */
+                   HANDLE_SBR_FRAME_DATA  h_sbr_data,      /*!< pointer to current data */
+                   HANDLE_SBR_PREV_FRAME_DATA h_prev_data  /*!< pointer to data of last frame */
+                   )
+{
+  FIXP_SGL target;  /* targeted level for sfb_nrg_prev during fade-down */
+  FIXP_SGL step;    /* speed of fade */
+  int i;
+
+  int currentStartPos = h_prev_data->stopPos - hHeaderData->numberTimeSlots;
+  int currentStopPos = hHeaderData->numberTimeSlots;
+
+
+  /* Use some settings of the previous frame */
+  h_sbr_data->ampResolutionCurrentFrame = h_prev_data->ampRes;
+  h_sbr_data->coupling = h_prev_data->coupling;
+  for(i=0;i<MAX_INVF_BANDS;i++)
+    h_sbr_data->sbr_invf_mode[i] = h_prev_data->sbr_invf_mode[i];
+
+  /* Generate concealing control data */
+
+  h_sbr_data->frameInfo.nEnvelopes = 1;
+  h_sbr_data->frameInfo.borders[0] = currentStartPos;
+  h_sbr_data->frameInfo.borders[1] = currentStopPos;
+  h_sbr_data->frameInfo.freqRes[0] = 1;
+  h_sbr_data->frameInfo.tranEnv = -1;  /* no transient */
+  h_sbr_data->frameInfo.nNoiseEnvelopes = 1;
+  h_sbr_data->frameInfo.bordersNoise[0] = currentStartPos;
+  h_sbr_data->frameInfo.bordersNoise[1] = currentStopPos;
+
+  h_sbr_data->nScaleFactors = hHeaderData->freqBandData.nSfb[1];
+
+  /* Generate fake envelope data */
+
+  h_sbr_data->domain_vec[0] = 1;
+
+  if (h_sbr_data->coupling == COUPLING_BAL) {
+    target = (FIXP_SGL)SBR_ENERGY_PAN_OFFSET;
+    step = (FIXP_SGL)DECAY_COUPLING;
+  }
+  else {
+    target = FL2FXCONST_SGL(0.0f);
+    step   = (FIXP_SGL)DECAY;
+  }
+  if (hHeaderData->bs_info.ampResolution == 0) {
+    target <<= 1;
+    step   <<= 1;
+  }
+
+  for (i=0; i < h_sbr_data->nScaleFactors; i++) {
+    if (h_prev_data->sfb_nrg_prev[i] > target)
+      h_sbr_data->iEnvelope[i] = -step;
+    else
+      h_sbr_data->iEnvelope[i] = step;
+  }
+
+  /* Noisefloor levels are always cleared ... */
+
+  h_sbr_data->domain_vec_noise[0] = 1;
+  for (i=0; i < hHeaderData->freqBandData.nNfb; i++)
+    h_sbr_data->sbrNoiseFloorLevel[i] = FL2FXCONST_SGL(0.0f);
+
+  /* ... and so are the sines */
+  FDKmemclear(h_sbr_data->addHarmonics, MAX_FREQ_COEFFS);
+}
+
+
+/*!
+  \brief   Build reference energies and noise levels from bitstream elements
+*/
+static void
+decodeEnvelope (HANDLE_SBR_HEADER_DATA hHeaderData,     /*!< Static control data */
+                HANDLE_SBR_FRAME_DATA  h_sbr_data,      /*!< pointer to current data */
+                HANDLE_SBR_PREV_FRAME_DATA h_prev_data, /*!< pointer to data of last frame */
+                HANDLE_SBR_PREV_FRAME_DATA otherChannel /*!< other channel's last frame data */
+                )
+{
+  int i;
+  int fFrameError = hHeaderData->frameErrorFlag;
+  FIXP_SGL tempSfbNrgPrev[MAX_FREQ_COEFFS];
+
+  if (!fFrameError) {
+    /*
+      To avoid distortions after bad frames, set the error flag if delta coding in time occurs.
+      However, SBR can take a little longer to come up again.
+    */
+    if ( h_prev_data->frameErrorFlag ) {
+      if (h_sbr_data->domain_vec[0] != 0) {
+        fFrameError = 1;
+      }
+    } else {
+      /* Check that the previous stop position and the current start position match.
+         (Could be done in checkFrameInfo(), but the previous frame data is not available there) */
+      if ( h_sbr_data->frameInfo.borders[0] != h_prev_data->stopPos - hHeaderData->numberTimeSlots ) {
+        /* Both the previous as well as the current frame are flagged to be ok, but they do not match! */
+        if (h_sbr_data->domain_vec[0] == 1) {
+          /* Prefer concealment over delta-time coding between the mismatching frames */
+          fFrameError = 1;
+        }
+        else {
+          /* Close the gap in time by triggering timeCompensateFirstEnvelope() */
+          fFrameError = 1;
+        }
+      }
+    }
+  }
+
+
+  if (fFrameError)       /* Error is detected */
+    {
+      leanSbrConcealment(hHeaderData,
+                         h_sbr_data,
+                         h_prev_data);
+
+      /* decode the envelope data to linear PCM */
+      deltaToLinearPcmEnvelopeDecoding (hHeaderData, h_sbr_data, h_prev_data);
+    }
+  else                          /*Do a temporary dummy decoding and check that the envelope values are within limits */
+    {
+      if (h_prev_data->frameErrorFlag) {
+        timeCompensateFirstEnvelope (hHeaderData, h_sbr_data, h_prev_data);
+        if (h_sbr_data->coupling != h_prev_data->coupling) {
+          /*
+            Coupling mode has changed during concealment.
+             The stored energy levels need to be converted.
+           */
+          for (i = 0; i < hHeaderData->freqBandData.nSfb[1]; i++) {
+            /* Former Level-Channel will be used for both channels */
+            if (h_prev_data->coupling == COUPLING_BAL)
+              h_prev_data->sfb_nrg_prev[i] = otherChannel->sfb_nrg_prev[i];
+            /* Former L/R will be combined as the new Level-Channel */
+            else if (h_sbr_data->coupling == COUPLING_LEVEL)
+              h_prev_data->sfb_nrg_prev[i] = (h_prev_data->sfb_nrg_prev[i] + otherChannel->sfb_nrg_prev[i]) >> 1;
+            else if (h_sbr_data->coupling == COUPLING_BAL)
+              h_prev_data->sfb_nrg_prev[i] = (FIXP_SGL)SBR_ENERGY_PAN_OFFSET;
+          }
+        }
+      }
+      FDKmemcpy (tempSfbNrgPrev, h_prev_data->sfb_nrg_prev,
+              MAX_FREQ_COEFFS * sizeof (FIXP_SGL));
+
+      deltaToLinearPcmEnvelopeDecoding (hHeaderData, h_sbr_data, h_prev_data);
+
+      fFrameError = checkEnvelopeData (hHeaderData, h_sbr_data, h_prev_data);
+
+      if (fFrameError)
+        {
+          hHeaderData->frameErrorFlag = 1;
+          FDKmemcpy (h_prev_data->sfb_nrg_prev, tempSfbNrgPrev,
+                  MAX_FREQ_COEFFS * sizeof (FIXP_SGL));
+          decodeEnvelope (hHeaderData, h_sbr_data, h_prev_data, otherChannel);
+          return;
+        }
+    }
+
+  requantizeEnvelopeData (h_sbr_data, h_sbr_data->ampResolutionCurrentFrame);
+
+  hHeaderData->frameErrorFlag = fFrameError;
+}
+
+
+/*!
+  \brief   Verify that envelope energies are within the allowed range
+  \return  0 if all is fine, 1 if an envelope value was too high
+*/
+static int
+checkEnvelopeData (HANDLE_SBR_HEADER_DATA hHeaderData,     /*!< Static control data */
+                   HANDLE_SBR_FRAME_DATA h_sbr_data,       /*!< pointer to current data */
+                   HANDLE_SBR_PREV_FRAME_DATA h_prev_data  /*!< pointer to data of last frame */
+                   )
+{
+  FIXP_SGL *iEnvelope = h_sbr_data->iEnvelope;
+  FIXP_SGL *sfb_nrg_prev = h_prev_data->sfb_nrg_prev;
+  int    i = 0, errorFlag = 0;
+  FIXP_SGL sbr_max_energy =
+    (h_sbr_data->ampResolutionCurrentFrame == 1) ? SBR_MAX_ENERGY : (SBR_MAX_ENERGY << 1);
+
+  /*
+    Range check for current energies
+  */
+  for (i = 0; i < h_sbr_data->nScaleFactors; i++) {
+    if (iEnvelope[i] > sbr_max_energy) {
+      errorFlag = 1;
+    }
+    if (iEnvelope[i] < FL2FXCONST_SGL(0.0f)) {
+      errorFlag = 1;
+      /* iEnvelope[i] = FL2FXCONST_SGL(0.0f); */
+    }
+  }
+
+  /*
+    Range check for previous energies
+  */
+  for (i = 0; i < hHeaderData->freqBandData.nSfb[1]; i++) {
+    sfb_nrg_prev[i] = fixMax(sfb_nrg_prev[i], FL2FXCONST_SGL(0.0f));
+    sfb_nrg_prev[i] = fixMin(sfb_nrg_prev[i], sbr_max_energy);
+  }
+
+  return (errorFlag);
+}
+
+
+/*!
+  \brief   Verify that the noise levels are within the allowed range
+
+  The function is equivalent to checkEnvelopeData().
+  When the noise-levels are being decoded, it is already too late for
+  concealment. Therefore the noise levels are simply limited here.
+*/
+static void
+limitNoiseLevels(HANDLE_SBR_HEADER_DATA hHeaderData,     /*!< Static control data */
+                 HANDLE_SBR_FRAME_DATA h_sbr_data)       /*!< pointer to current data */
+{
+  int i;
+  int nNfb = hHeaderData->freqBandData.nNfb;
+
+  /*
+    Set range limits. The exact values depend on the coupling mode.
+    However this limitation is primarily intended to avoid unlimited
+    accumulation of the delta-coded noise levels.
+  */
+  #define lowerLimit   ((FIXP_SGL)0)     /* lowerLimit actually refers to the _highest_ noise energy */
+  #define upperLimit   ((FIXP_SGL)35)    /* upperLimit actually refers to the _lowest_ noise energy */
+
+  /*
+    Range check for current noise levels
+  */
+  for (i = 0; i < h_sbr_data->frameInfo.nNoiseEnvelopes * nNfb; i++) {
+    h_sbr_data->sbrNoiseFloorLevel[i] = fixMin(h_sbr_data->sbrNoiseFloorLevel[i], upperLimit);
+    h_sbr_data->sbrNoiseFloorLevel[i] = fixMax(h_sbr_data->sbrNoiseFloorLevel[i], lowerLimit);
+  }
+}
+
+
+/*!
+  \brief   Compensate for the wrong timing that might occur after a frame error.
+*/
+static void
+timeCompensateFirstEnvelope (HANDLE_SBR_HEADER_DATA hHeaderData, /*!< Static control data */
+                             HANDLE_SBR_FRAME_DATA h_sbr_data,   /*!< pointer to actual data */
+                             HANDLE_SBR_PREV_FRAME_DATA h_prev_data)  /*!< pointer to data of last frame */
+{
+  int i, nScalefactors;
+  FRAME_INFO *pFrameInfo = &h_sbr_data->frameInfo;
+  UCHAR *nSfb = hHeaderData->freqBandData.nSfb;
+  int estimatedStartPos = h_prev_data->stopPos - hHeaderData->numberTimeSlots;
+  int refLen, newLen, shift;
+  FIXP_SGL  deltaExp;
+
+  /* Original length of first envelope according to bitstream */
+  refLen = pFrameInfo->borders[1] - pFrameInfo->borders[0];
+  /* Corrected length of first envelope (concealing can make the first envelope longer) */
+  newLen = pFrameInfo->borders[1] - estimatedStartPos;
+
+  if (newLen <= 0) {
+    /* An envelope length of <= 0 would not work, so we don't use it.
+       May occur if the previous frame was flagged bad due to a mismatch
+       of the old and new frame infos. */
+    newLen = refLen;
+    estimatedStartPos = pFrameInfo->borders[0];
+  }
+
+  deltaExp = FDK_getNumOctavesDiv8(newLen, refLen);
+
+  /* Shift by -3 to rescale ld-table, 1-ampRes to enable coarser steps */
+  shift = (FRACT_BITS - 1 - ENV_EXP_FRACT + 1 - h_sbr_data->ampResolutionCurrentFrame - 3);
+  deltaExp = deltaExp >> shift;
+  pFrameInfo->borders[0] = estimatedStartPos;
+  pFrameInfo->bordersNoise[0] = estimatedStartPos;
+
+  if (h_sbr_data->coupling != COUPLING_BAL) {
+    nScalefactors = (pFrameInfo->freqRes[0]) ? nSfb[1] : nSfb[0];
+
+    for (i = 0; i < nScalefactors; i++)
+      h_sbr_data->iEnvelope[i] = h_sbr_data->iEnvelope[i] + deltaExp;
+  }
+}
+
+
+
+/*!
+  \brief   Convert each envelope value from logarithmic to linear domain
+
+  Energy levels are transmitted in powers of 2, i.e. only the exponent
+  is extracted from the bitstream.
+  Therefore, normally only integer exponents can occur. However during
+  fading (in case of a corrupt bitstream), a fractional part can also
+  occur. The data in the array iEnvelope is shifted left by ENV_EXP_FRACT
+  compared to an integer representation so that numbers smaller than 1
+  can be represented.
+
+  This function calculates a mantissa corresponding to the fractional
+  part of the exponent for each reference energy. The array iEnvelope
+  is converted in place to save memory. Input and output data must
+  be interpreted differently, as shown in the below figure:
+
+  \image html  EnvelopeData.png
+
+  The data is then used in calculateSbrEnvelope().
+*/
+static void
+requantizeEnvelopeData (HANDLE_SBR_FRAME_DATA h_sbr_data, int ampResolution)
+{
+  int i;
+  FIXP_SGL mantissa;
+  int ampShift = 1 - ampResolution;
+  int exponent;
+
+  /* In case that ENV_EXP_FRACT is changed to something else but 0 or 8,
+     the initialization of this array has to be adapted!
+  */
+#if ENV_EXP_FRACT
+  static const FIXP_SGL pow2[ENV_EXP_FRACT] =
+  {
+    FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 1))), /* 0.7071 */
+    FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 2))), /* 0.5946 */
+    FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 3))),
+    FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 4))),
+    FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 5))),
+    FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 6))),
+    FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 7))),
+    FL2FXCONST_SGL(0.5f * pow(2.0f, pow(0.5f, 8)))  /* 0.5013 */
+  };
+
+  int bit, mask;
+#endif
+
+  for (i = 0; i < h_sbr_data->nScaleFactors; i++) {
+    exponent = (LONG)h_sbr_data->iEnvelope[i];
+
+#if ENV_EXP_FRACT
+
+    exponent = exponent >> ampShift;
+    mantissa = 0.5f;
+
+    /* Amplify mantissa according to the fractional part of the
+       exponent (result will be between 0.500000 and 0.999999)
+    */
+    mask = 1;  /* begin with lowest bit of exponent */
+
+    for ( bit=ENV_EXP_FRACT-1; bit>=0; bit-- ) {
+      if (exponent & mask) {
+        /* The current bit of the exponent is set,
+           multiply mantissa with the corresponding factor: */
+        mantissa = (FIXP_SGL)( (mantissa * pow2[bit]) << 1);
+      }
+      /* Advance to next bit */
+      mask = mask << 1;
+    }
+
+    /* Make integer part of exponent right aligned */
+    exponent = exponent >> ENV_EXP_FRACT;
+
+#else
+    /* In case of the high amplitude resolution, 1 bit of the exponent gets lost by the shift.
+       This will be compensated by a mantissa of 0.5*sqrt(2) instead of 0.5 if that bit is 1. */
+    mantissa = (exponent & ampShift) ? FL2FXCONST_SGL(0.707106781186548f) : FL2FXCONST_SGL(0.5f);
+    exponent = exponent >> ampShift;
+#endif
+
+    /*
+      Mantissa was set to 0.5 (instead of 1.0, therefore increase exponent by 1).
+      Multiply by L=nChannels=64 by increasing exponent by another 6.
+      => Increase exponent by 7
+    */
+    exponent += 7 + NRG_EXP_OFFSET;
+
+    /* Combine mantissa and exponent and write back the result */
+    h_sbr_data->iEnvelope[i] = (FIXP_SGL)(((LONG)mantissa & MASK_M) | (exponent & MASK_E));
+
+  }
+}
+
+
+/*!
+  \brief   Build new reference energies from old ones and delta coded data
+*/
+static void
+deltaToLinearPcmEnvelopeDecoding (HANDLE_SBR_HEADER_DATA hHeaderData,     /*!< Static control data */
+                                  HANDLE_SBR_FRAME_DATA h_sbr_data,       /*!< pointer to current data */
+                                  HANDLE_SBR_PREV_FRAME_DATA h_prev_data) /*!< pointer to previous data */
+{
+  int i, domain, no_of_bands, band, freqRes;
+
+  FIXP_SGL *sfb_nrg_prev = h_prev_data->sfb_nrg_prev;
+  FIXP_SGL *ptr_nrg = h_sbr_data->iEnvelope;
+
+  int offset = 2 * hHeaderData->freqBandData.nSfb[0] - hHeaderData->freqBandData.nSfb[1];
+
+  for (i = 0; i < h_sbr_data->frameInfo.nEnvelopes; i++) {
+    domain = h_sbr_data->domain_vec[i];
+    freqRes = h_sbr_data->frameInfo.freqRes[i];
+
+    FDK_ASSERT(freqRes >= 0 && freqRes <= 1);
+
+    no_of_bands = hHeaderData->freqBandData.nSfb[freqRes];
+
+    FDK_ASSERT(no_of_bands < (64));
+
+    if (domain == 0)
+    {
+      mapLowResEnergyVal(*ptr_nrg, sfb_nrg_prev, offset, 0, freqRes);
+      ptr_nrg++;
+      for (band = 1; band < no_of_bands; band++)
+      {
+        *ptr_nrg = *ptr_nrg + *(ptr_nrg-1);
+        mapLowResEnergyVal(*ptr_nrg, sfb_nrg_prev, offset, band, freqRes);
+        ptr_nrg++;
+      }
+    }
+    else
+    {
+      for (band = 0; band < no_of_bands; band++)
+      {
+        *ptr_nrg = *ptr_nrg + sfb_nrg_prev[indexLow2High(offset, band, freqRes)];
+        mapLowResEnergyVal(*ptr_nrg, sfb_nrg_prev, offset, band, freqRes);
+        ptr_nrg++;
+      }
+    }
+  }
+}
+
+
+/*!
+  \brief   Build new noise levels from old ones and delta coded data
+*/
+static void
+decodeNoiseFloorlevels (HANDLE_SBR_HEADER_DATA hHeaderData,     /*!< Static control data */
+                        HANDLE_SBR_FRAME_DATA h_sbr_data,       /*!< pointer to current data */
+                        HANDLE_SBR_PREV_FRAME_DATA h_prev_data) /*!< pointer to previous data */
+{
+  int i;
+  int nNfb = hHeaderData->freqBandData.nNfb;
+  int nNoiseFloorEnvelopes = h_sbr_data->frameInfo.nNoiseEnvelopes;
+
+  /* Decode first noise envelope */
+
+  if (h_sbr_data->domain_vec_noise[0] == 0) {
+    FIXP_SGL noiseLevel = h_sbr_data->sbrNoiseFloorLevel[0];
+    for (i = 1; i < nNfb; i++) {
+      noiseLevel += h_sbr_data->sbrNoiseFloorLevel[i];
+      h_sbr_data->sbrNoiseFloorLevel[i] = noiseLevel;
+    }
+  }
+  else {
+    for (i = 0; i < nNfb; i++) {
+      h_sbr_data->sbrNoiseFloorLevel[i] += h_prev_data->prevNoiseLevel[i];
+    }
+  }
+
+  /* If present, decode the second noise envelope
+     Note:  nNoiseFloorEnvelopes can only be 1 or 2 */
+
+  if (nNoiseFloorEnvelopes > 1) {
+    if (h_sbr_data->domain_vec_noise[1] == 0) {
+      FIXP_SGL noiseLevel = h_sbr_data->sbrNoiseFloorLevel[nNfb];
+      for (i = nNfb + 1; i < 2*nNfb; i++) {
+        noiseLevel += h_sbr_data->sbrNoiseFloorLevel[i];
+        h_sbr_data->sbrNoiseFloorLevel[i] = noiseLevel;
+      }
+    }
+    else {
+      for (i = 0; i < nNfb; i++) {
+        h_sbr_data->sbrNoiseFloorLevel[i + nNfb] += h_sbr_data->sbrNoiseFloorLevel[i];
+      }
+    }
+  }
+
+  limitNoiseLevels(hHeaderData, h_sbr_data);
+
+  /* Update prevNoiseLevel with the last noise envelope */
+  for (i = 0; i < nNfb; i++)
+    h_prev_data->prevNoiseLevel[i] = h_sbr_data->sbrNoiseFloorLevel[i + nNfb*(nNoiseFloorEnvelopes-1)];
+
+
+  /* Requantize the noise floor levels in COUPLING_OFF-mode */
+  if (!h_sbr_data->coupling) {
+    int nf_e;
+
+    for (i = 0; i < nNoiseFloorEnvelopes*nNfb; i++) {
+      nf_e = 6 - (LONG)h_sbr_data->sbrNoiseFloorLevel[i] + 1 + NOISE_EXP_OFFSET;
+      /* +1 to compensate for a mantissa of 0.5 instead of 1.0 */
+
+      h_sbr_data->sbrNoiseFloorLevel[i] =
+        (FIXP_SGL)( ((LONG)FL2FXCONST_SGL(0.5f)) +  /* mantissa */
+                  (nf_e & MASK_E) ); /* exponent */
+
+    }
+  }
+}