[mythtv-users] Frame Drop problems??

mojo mojospam at thegeekclub.net
Wed Jul 9 05:55:27 EDT 2003


David Madsen wrote:

> 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
> 

i have been getting similar results when converting to divx .avi's with 
a 2-pass mencoder run... audio is slightly out of sync... for me, the 
duplicate frame errors are not centralized to that one part of the file 
though, they are scattered throughout most of the file...  i was using 
mpeg4 640x480 2200 kbps, vhq, v4mv, on an athlon xp 1700.. and was 
pushing my cpu up to 90% or so, so i just lowered my settings 
considerably and am going to wait for the next recording to convert and 
test... my mencoder conversion settings dont seem to make much 
difference on the audio sync... from my understanding (searching 
mplayers mailing list archives) those duplicate frame errors are 
definitely bad news and im guessing are whats causing my problems.

Sean



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