diff --git a/src/app/basicMP4Writer.cpp b/src/app/basicMP4Writer.cpp
index ae5941a..5558a10 100644
--- a/src/app/basicMP4Writer.cpp
+++ b/src/app/basicMP4Writer.cpp
@@ -87,6 +87,20 @@ int BasicMP4Writer::addFrameAU (const uint8_t* byteBuf, const uint32_t byteCount
   if (((m_frameCount++) % m_rndAccPeriod) == 0) // add RAP to list (stco)
   {
     m_rndAccOffsets.push_back (m_mediaSize);
+#ifndef NO_PREROLL_DATA
+    if (((m_frameCount - 1u) % (m_rndAccPeriod << 1)) == 0)  // every 2nd
+    {
+      if ((byteBuf[0] & 0xE0) == 0xC0) // IPF?
+      {
+        // byte-offset of UsacConfig() in AU (excl. first 5 config bits!)
+        m_ipfCfgOffsets.push_back (byteBuf[0] == 0xDF && (byteBuf[1] & 0xE0) == 0xE0 ? 5 : 3);
+      }
+      else // 3-bit ID is missing, not an IPF!
+      {
+        m_ipfCfgOffsets.push_back (0);
+      }
+    }
+#endif
   }
   m_mediaSize += byteCount;
 
@@ -425,6 +439,37 @@ void BasicMP4Writer::reset (const unsigned frameLength /*= 0*/, const unsigned p
   m_sampleRate   = 0;
   m_dynamicHeader.clear ();
   m_rndAccOffsets.clear ();
+#ifndef NO_PREROLL_DATA
+  m_ipfCfgOffsets.clear ();
+#endif
 
   if (m_fileHandle != -1) _SEEK (m_fileHandle, 0, 0 /*SEEK_SET*/);
 }
+
+#ifndef NO_PREROLL_DATA
+int BasicMP4Writer::updateIPFs (const uint8_t* ascUcBuf, const uint32_t ascUcLength, const uint32_t ucOffset)
+{
+  const uint8_t bw = uint8_t (ascUcLength - ucOffset);
+  int bytesWritten = 0, configsWritten = 0;
+
+  if ((m_fileHandle == -1) || (ascUcBuf == nullptr) || (ascUcLength == 0) || (ascUcLength <= ucOffset))
+  {
+    return 1; // invalid file handle or IPF config parameter
+  }
+
+  // write updated UsacConfig() to AudioPreRoll() extensions
+  for (uint32_t i = 0; i < (uint32_t) m_ipfCfgOffsets.size (); i++)
+  {
+    const uint32_t configOffset = m_ipfCfgOffsets.at (i);
+
+    if (configOffset > 0) // this AU is an IPF
+    {
+      _SEEK (m_fileHandle, m_rndAccOffsets.at (i << 1) + m_mediaOffset + configOffset, 0 /*SEEK_SET*/);
+      bytesWritten += _WRITE (m_fileHandle, &ascUcBuf[ucOffset], bw);
+      configsWritten++;
+    }
+  }
+
+  return (bytesWritten != configsWritten * bw ? 1 : 0);
+}
+#endif
diff --git a/src/app/basicMP4Writer.h b/src/app/basicMP4Writer.h
index 9c91cad..95d1110 100755
--- a/src/app/basicMP4Writer.h
+++ b/src/app/basicMP4Writer.h
@@ -43,6 +43,9 @@ private:
   uint8_t  m_staticHeader[STAT_HEADER_SIZE]; // fixed-size
   std::vector <uint8_t> m_dynamicHeader; // variable-sized
   std::vector <uint32_t> m_rndAccOffsets; // random access
+#ifndef NO_PREROLL_DATA
+  std::vector <uint8_t> m_ipfCfgOffsets; // IPF UsacConfig
+#endif
 
   // helper function
   void push32BitValue (const uint32_t value); // to header
@@ -52,7 +55,11 @@ public:
   // constructor
   BasicMP4Writer () { m_fileHandle = -1;  reset (); }
   // destructor
+#ifdef NO_PREROLL_DATA
   ~BasicMP4Writer() { m_dynamicHeader.clear (); m_rndAccOffsets.clear (); }
+#else
+  ~BasicMP4Writer() { m_dynamicHeader.clear (); m_rndAccOffsets.clear (); m_ipfCfgOffsets.clear (); }
+#endif
   // public functions
   int addFrameAU (const uint8_t* byteBuf, const uint32_t byteCount);
   int finishFile (const unsigned avgBitrate, const unsigned maxBitrate, const uint32_t audioLength,
@@ -64,6 +71,9 @@ public:
                   const unsigned raPeriod, const uint8_t* ascBuf,      const unsigned ascSize,
                   const uint32_t creatTime = 0, const char vbrQuality = 0);
   void     reset (const unsigned frameLength = 0, const unsigned pregapLength = 0, const unsigned raPeriod = 0);
+#ifndef NO_PREROLL_DATA
+  int updateIPFs (const uint8_t* ascUcBuf, const uint32_t ascUcLength, const uint32_t ucOffset);
+#endif
 }; // BasicMP4Writer
 
 #endif // _BASIC_MP4_WRITER_H_
diff --git a/src/app/exhaleApp.cpp b/src/app/exhaleApp.cpp
index ff19d6a..23384a9 100644
--- a/src/app/exhaleApp.cpp
+++ b/src/app/exhaleApp.cpp
@@ -1016,6 +1016,13 @@ int main (const int argc, char* argv[])
         bw = EA_LOUD_INIT | (qPeak << 18) | (qLoud << 6) | 11u;
         memset (outAuData, 0, 108 * sizeof (uint8_t)); // max allowed ASC + UC size
         i = exhaleEnc.initEncoder (outAuData, &bw); // with finished loudnessInfo()
+#ifndef NO_PREROLL_DATA
+        if (i == 0)
+        {
+          i = __min (USHRT_MAX, wavReader.getSampleRate ());
+          i = (uint16_t) mp4Writer.updateIPFs (outAuData, bw, (i == 57600 || i == 38400 || i == 19200 /*BL USAC*/ ? 6 : 3));
+        }
+#endif
       }
       // mean & max. bit-rate of encoded AUs
       br = uint32_t (((actualLength >> 1) + 8 * (byteCount + 4 * (int64_t) mp4Writer.getFrameCount ()) * sampleRate) / actualLength);