[mythtv-users] Frame Drop problems??

David Madsen madsend at myrealbox.com
Tue Jul 8 15:00:29 EDT 2003


Recently I have been noticing something strange happening in the backend
while recording.  I convert some the recorded files into mpegs for archiving
by using mencoder to reencode the video.  while running mencoder about
halfway through the file it runs into a chunk of the .nuv file and dumps out
a whole bunch of these messages, which I believe to be parts of the file
where the backend has dropped video frames.

1 duplicate frame(s)!
Pos:1731.3s  51807f (46%) 219fps Trem:   4min 1529mb  A-V:-0.067 [3333:96]
1 duplicate frame(s)!
Pos:1731.6s  51817f (46%) 219fps Trem:   4min 1529mb  A-V:-0.067 [3333:96]
1 duplicate frame(s)!
Pos:1732.0s  51827f (46%) 219fps Trem:   4min 1529mb  A-V:-0.067 [3333:96]
1 duplicate frame(s)!
Pos:1732.4s  51837f (46%) 219fps Trem:   4min 1529mb  A-V:-0.067 [3333:96]
1 duplicate frame(s)!
Pos:1732.7s  51847f (46%) 219fps Trem:   4min 1528mb  A-V:-0.067 [3333:96]
1 duplicate frame(s)!
Pos:1733.1s  51857f (46%) 219fps Trem:   4min 1528mb  A-V:-0.067 [3333:96]


The strange thing about this is that there are no dropped frames in any
other part of the file, just consolidated to one group about halfway through
recording a 1 hour show.  I have looked through the system and there are no
other crons or anything starting up that would cause something like this to
happen. It also happens no matter what time of the day it is recording.  I'm
wondering if anyone else has noticed something similar?  in the resulting
file after mencoder is finished there is a section of the file where the
missing frames are visible and causes the audio to go out of sync for a few
minutes.  I am recording at 640x480, 3300 bps  on a Athlon XP 2000+.  the
CPU stays around 35-40% utilized while recording.  DMA is turned on and
hdparm reports about 40MB/s.  I can't see what would be causing it to drop
frames.  Any ideas?

David Madsen



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