[mythtv] Mythtv mpeg frame counting - patch?

[Bill]

Mythtv does not always count frames correctly for mpeg files (ref ticket 799 
comment from danielk).  As a result the length shown in the OSD is sometimes 
too short (more often than not for my mpeg video files).  I am looking at 
writing a patch for this, but want to ask for feedback on a number of things 
first

1. Is anyone else already working on a patch?  I don't want to duplicate 
effort.
2. Any thoughts or ideas on the patch?  Ticket #1693 looks like it might be 
a useful starting point.
3. Anything to watch out for that could break as a result?  I can only test 
DVB and mpeg playback.  Can't test IVTV and other stuff.

I had planned to write a patch for playback only first, then possibly 
address recording after that.  The recording patch would be necessary to 
generate the correct position map after the playback patch.  Right now both 
recording and playback mis-count frames in the same way.