[mythtv-users] Recording Quality [0.16]

[Mark Staudinger]

Joe White writes:

> I first installed MythTV 0.16 in Jan 2005. It worked perfectly and I was 
> smug and content.  I didn't tweak the box any beyond the parameters of 
> Jarod's basic install instructions on the principle that if it ain't broke 
> don't fix it.  For three months all was good.  Then on April 13 the video 
> and audio quality began to degrade.  Old shows still play flawlessly, but 
> newly recorded shows tend to flash, chirp loudly and have intermittant 
> blockiness.  Since then I have made adjustments to the recording profiles 
> bit rates based on archival information in this list.  I have tightened my 
> cable connection with a wrench.  I have also done some half-heated 
> experimentation with TV playback, but since only new recordings seem to be 
> affected, I haven't invested much there.
> 
> I am coming to the conclusion that either the cable quality has degraded 
> or the PVR-250(not MCE) is going bad.  Any thoughts on the matter?
> 

I had similar issues that would occur after a few days uptime.  Once the 
quality degraded, it continued to be degraded for subsequent recordings, for 
all channels and recording profiles.  A reboot would solve the issue for 
another day or three.  

I believe the issue was that the PVR-250 was overheating.  I can no longer 
prove it, though.  I am using an MSI Hermes 845GV case, and the way the slots 
are laid out, when the box is horizontal, the heat-producing components on 
the PVR-250 were underneath the card and not well ventilated.

I moved the card to the upper slot to give it more space between the card and 
the motherboard, and re-oriented the case vertically with the card at the 
top.  I also put a small fan above the card itself, to help pull warm air out 
of the case and away from the card.

I haven't had this problem since.  However, I also abandoned my bug-ridden 
SuSE / Xfree86 installation and moved to a problem-free Gentoo / Xorg-X11 
installation within a few days of re-orientation, so I can't state with 
absolute certainty that it was a heat issue.  It's certainly worth looking 
into, though.  If it's due to heat, then shutting the machine down for 15 
minutes or so, and then recording a program or watching TV should let you 
know.  Although it's odd that this would happen after 3 months of good 
results, unless you lost some cooling fan(s) in the case, or the ambient 
temperature rose drastically.

As far as cable interference, any problem that would yield a noticeably 
distorted picture from the PVR-250, would probably be noticeable on your TV 
as well when watching direct.  You can always try swapping the cable segments 
between your TV and the PVR-250, as well.  

Another possibility is interference from another internal device - have you 
added any hardware to the box?

Good Luck!
-=Mark