diff --git a/ChangeLog b/ChangeLog
index aacc137b2..3b7614f9b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2009-05-07  Moritz Bunkus  <moritz@bunkus.org>
+
+	* mkvmerge, mmg: enhancement: Made mmg's "FPS" input field
+	available for all video tracks. mkvmerge's corresponding option
+	"--default-duration" now not only modifies the track header field
+	but affects the frame timecodes as well.
+
 2009-05-06  Moritz Bunkus  <moritz@bunkus.org>
 
 	* mkvmerge: bug fix: The VobSub reader was dropping the very last
diff --git a/src/merge/pr_generic.cpp b/src/merge/pr_generic.cpp
index 63d9e84c4..1eab4b470 100644
--- a/src/merge/pr_generic.cpp
+++ b/src/merge/pr_generic.cpp
@@ -236,6 +236,12 @@ generic_packetizer_c::generic_packetizer_c(generic_reader_c *p_reader,
     hserialno = create_track_number(reader, ti.id);
 
   timecode_factory = timecode_factory_c::create(ti.ext_timecodes, ti.fname, ti.id);
+
+  // If no external timecode file but a default duration has been
+  // given then create a simple timecode factory that generates the
+  // timecodes for the given FPS.
+  if ((NULL == timecode_factory.get()) && (-1 != htrack_default_duration))
+    timecode_factory = timecode_factory_c::create_fps_factory(htrack_default_duration, ti.fname, ti.id);
 }
 
 generic_packetizer_c::~generic_packetizer_c() {
diff --git a/src/merge/timecode_factory.cpp b/src/merge/timecode_factory.cpp
index b6819ff2d..cbc9793d7 100644
--- a/src/merge/timecode_factory.cpp
+++ b/src/merge/timecode_factory.cpp
@@ -18,6 +18,7 @@
 
 #include "common/common.h"
 #include "common/mm_io.h"
+#include "common/string_formatting.h"
 #include "common/string_parsing.h"
 #include "merge/pr_generic.h"
 #include "merge/timecode_factory.h"
@@ -63,6 +64,21 @@ timecode_factory_c::create(const string &file_name,
   return timecode_factory_cptr(factory);
 }
 
+timecode_factory_cptr
+timecode_factory_c::create_fps_factory(int64_t default_duration,
+                                       const string &source_name,
+                                       int64_t tid) {
+  mm_text_io_c text_io(new mm_mem_io_c(NULL, 0, 1024));
+  text_io.puts("# timecode format v1\n");
+  text_io.puts(boost::format("assume %1%\n") % to_string(1000000000.0 / default_duration, 9));
+  text_io.setFilePointer(0, seek_beginning);
+
+  timecode_factory_cptr factory(new timecode_factory_v1_c("dummy", source_name, tid));
+  factory->parse(text_io);
+
+  return factory;
+}
+
 void
 timecode_factory_v1_c::parse(mm_io_c &in) {
   string line;
diff --git a/src/merge/timecode_factory.h b/src/merge/timecode_factory.h
index 94175da45..bfb5befbf 100644
--- a/src/merge/timecode_factory.h
+++ b/src/merge/timecode_factory.h
@@ -95,6 +95,7 @@ public:
   }
 
   static timecode_factory_cptr create(const string &file_name, const string &source_name, int64_t tid);
+  static timecode_factory_cptr create_fps_factory(int64_t default_duration, const string &source_name, int64_t tid);
 };
 
 class timecode_factory_v1_c: public timecode_factory_c {
diff --git a/src/mmg/tab_input_format.cpp b/src/mmg/tab_input_format.cpp
index 39c72723d..d05018b34 100644
--- a/src/mmg/tab_input_format.cpp
+++ b/src/mmg/tab_input_format.cpp
@@ -256,8 +256,8 @@ tab_input_format::set_track_mode(mmg_track_t *t) {
   cob_fourcc->Enable(video);
   st_stereo_mode->Enable(video);
   cob_stereo_mode->Enable(video);
-  st_fps->Enable(avc_es);
-  cob_fps->Enable(avc_es);
+  st_fps->Enable(video);
+  cob_fps->Enable(video);
   st_nalu_size_length->Enable(avc || avc_es);
   cob_nalu_size_length->Enable(avc || avc_es);
   st_compression->Enable((ctype.Find(wxT("vobsub")) >= 0) && !appending);
diff --git a/src/output/p_avc.cpp b/src/output/p_avc.cpp
index 12912e7b4..72717ccfa 100644
--- a/src/output/p_avc.cpp
+++ b/src/output/p_avc.cpp
@@ -55,6 +55,14 @@ mpeg4_p10_es_video_packetizer_c(generic_reader_c *p_reader,
   set_codec_private(m_avcc->get(), m_avcc->get_size());
   extract_aspect_ratio();
   m_parser.set_keep_ar_info(false);
+
+  // If no external timecode file has been specified then mkvmerge
+  // might have created a factory due to the --default-duration
+  // command line argument. This factory must be disabled for the AVC
+  // packetizer because it takes care of handling the default
+  // duration/FPS itself.
+  if (ti.ext_timecodes.empty())
+    timecode_factory = timecode_factory_cptr(NULL);
 }
 
 void