[mythtv-users] Incorrect length in OSD for MPG videos

Bill level42 at sympatico.ca
Sat Jun 2 17:51:44 UTC 2007

Trying to track done the source of the problem, I have several MPEG movies 
recorded from DVB that mythtv reports the incorrect length in the OSD.  This 
is the cause whether from "view recordings" or after I move them to 
mythvideo (and use mythtranscode to re-generate position map).  As yes I 
have a good position map.

Mythtv determines the length from the frame number of the last key frame in 
the position map (from recordedseek for recordings; or filemarkup for 
videos). Here an example:

Video length is actually 2:14:53, but mythtv reports it as 1:48:26.  Have 
confirm that the actual mythtv play time is 2:14, but the OSD reports on 
1:48.  The entry in the position map (recordedseek or filemarkup) is 195006 
which is 195006/29.97 = 6506 seconds or 108 minutes (1:48).  To determine 
the the position in the recording/video, mythtv counts the frames played, 
multiplies by the frame rate.  This seems to all make sense, but I can not 
explain/understand why the discrepancy between the actual play time and the 
calculated run time.  Doesn't matter if the video is played from "view 
recordings" or from mythvideo, same results.

When mythtv reads the mpeg, it does note in the log that it is 6506 seconds 
long and that it's frame rate is 29.97.  I presume this comes from the mpeg 
file header, as other video player software show the same thing.

When I play in other software, they report the play time correctly.

It almost seems like the actual frame rate in the file is 23.97 and mythtv 
is automatically compensating for this, but not telling me in the log 
messages and still counts the frames as if they were 29.97/sec.  The 23.97 
would make some sense to save bandwidth on DVB transmission.

Any suggestions where to look to fix this problem or as to the cause of the 

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