diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 8d2496d1..ec8163ed 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -1322,6 +1322,8 @@ Reinhard Nissl <rnissl@gmx.de>
  for reporting that the Transfer Mode indicator bitmap in the LCARS skin may not
  fit with small font sizes
  for reporting a race condition when zapping in transfer mode
+ for reporting an error in mapping the frame type bits when detecting independent
+ frames in MPEG 4 video
 
 Richard Robson <richard_robson@beeb.net>
  for reporting freezing replay if a timer starts while in Transfer Mode from the
diff --git a/HISTORY b/HISTORY
index b0e96dd0..d67c09e1 100644
--- a/HISTORY
+++ b/HISTORY
@@ -7235,7 +7235,9 @@ Video Disk Recorder Revision History
   function in order to make use of this new feature. See, for instance, the function
   cSkinClassicDisplayMenu::SetButtons() in skinclassic.c for details.
 
-2012-09-13: Version 1.7.31
+2012-09-14: Version 1.7.31
 
 - If regenerating an index file fails and no data is written to the file, VDR now
   reports this error and removes the empty index file.
+- Fixed mapping the frame type bits when detecting independent frames in MPEG 4
+  video (reported by Reinhard Nissl).
diff --git a/remux.c b/remux.c
index bd06e7ce..3698cc41 100644
--- a/remux.c
+++ b/remux.c
@@ -4,7 +4,7 @@
  * See the main source file 'vdr.c' for copyright information and
  * how to reach the author.
  *
- * $Id: remux.c 2.64 2012/03/02 10:56:49 kls Exp $
+ * $Id: remux.c 2.65 2012/09/14 09:06:14 kls Exp $
  */
 
 #include "remux.h"
@@ -974,8 +974,8 @@ int cFrameDetector::Analyze(const uchar *Data, int Length)
                                if (FrameTypeOffset >= TS_SIZE) // the byte to check is in the next TS packet
                                   i = SkipPackets(Data, Length, Processed, FrameTypeOffset);
                                newFrame = true;
-                               uchar FrameType = Data[FrameTypeOffset];
-                               independentFrame = FrameType == 0x10;
+                               uchar FrameType = Data[FrameTypeOffset] & 0xE0;
+                               independentFrame = FrameType == 0x00;
                                if (synced) {
                                   if (framesPerPayloadUnit < 0) {
                                      payloadUnitOfFrame = (payloadUnitOfFrame + 1) % -framesPerPayloadUnit;