[mythtv-users] one potential cause for stuttering (probably low runner)

[Ed Clark]

Hello All,

I just wanted to report on something I ran into that caused
stuttering on playback of HD material.  It is probably a low
runner problem, but it took me a while to find because I
wasn't expecting it.

And that is, the network connection on one of my frontends
dropped to 10 Mbps.

I had recently swapped out the motherboard and video card
on this box and also done an upgrade of MiniMyth.  Yes, I
know that I shouldn't make lots of changes at once, but all
of my quick tests along the way had shown everything working.

But, when it was all done, any HD material started stuttering
about once a second.  This was with the latest release of
MiniMyth.  I wound up rebuilding the box using CentOS 5.2
and then Fedora 8, but it still had the problem.  SD material
ran fine, but HD was skipping on me.  Looking at CPU usage,
I saw it running at only 40% to 50% max.

Playing around with the profiles helped some, but wouldn't
make the base problem go away.

After searching this mailing list, swearing, and tearing
some hair out, I just happened to watch the boot messages
after rebooting for the umpteenth time and saw the network
come up -- at 10 Mbps!

I had this box connected to a low end 100 Mbps router which
had been working fine the past couple of years.  But, now
it obviously wasn't.  I pulled the router out of the path
and connected directly to my core router in the basement.
It came up at full network rate.

Now the HD material played with no stuttering!

I guess my new motherboard (with a Gb chip) and the low
end router didn't handshaking well.

So, if you've got stuttering (in the once a second range)
and have run out of things to try, take a quick look at the
network speed between your frontend and backend.  Most
likely this isn't the problem, but it doesn't hurt to look.

Ed