[mythtv] jerky/jittery video on fast box?

William Preston bpreston at networkusa.net
Wed Jan 22 09:40:11 EST 2003


> I'm running Myth and getting jerky/jittery video.
> Video is jittery to very jittery in live TV mode (and sometimes, in
> playback mode).  It seems that the mpeg4 setting gives me better

I'm running into something similar, but I can't quite figure out what the
issue is.  My problem is that the audio blips--I'm really not sure that
the video stutters, but the audio 'drops' about every five seconds.
However, it's only for rtjpeg.  Does that make any sense?  If I record in
mpeg4 (any quality settings), I get perfect audio+video.  But if i switch
to rtjpeg, any quality settings, I get choppy audio.  I've tried the
matrox codec, but it just gives me a blank screen (used to work...not sure
why it doesn't anymore.)  I'm doing uncompressed audio for everything, so
lame shouldn't be the issue.  Changing sampling rate doesn't have any
effect.

I'm using the current CVS (as of two days ago), on a AthlonMP1600.  It's
not an issue of CPU--if I check top when doing liveTV with rtjpeg 255
quality, 640X480 I get 50->60% CPU utilization (that's backend+frontend.)
Disk seems fine--hdparm clocks it at 40MB/s.

Anyone have any ideas?  I've seen this through many of the .8 CVS
versions, but have never been able to explain it.  It's not _that_ big a
deal since mpeg4 is working...I just wanted to see if the nuppelvideo
would have a faster startup than mpeg4 (which seems to 'stutter' for a
second when switching channels, which is to be understood.)


I'm on an AMD 760MP board with 512RAM, using a BT878 and a Matrox G400.





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