A/V playback stuttery and getting worse - how to troubleshoot? (ubuntu 10.10)
 

I've been having a problem with intermittent stuttering in video and audio playback since upgrading to Maverick (it also happened when I briefly installed Lucid). It started out as the odd skip every 20 minutes or so but now it can happen 5 or 6 times in 10 minutes when watching a film.

I've tried:

reformatting and clean installing
using a half-dozen players
installing every codec I could think of (only after the normal ones wouldn't help)
diangosing my 3 hard drives (the problem occurs on them all and they're not in a RAID setup)
changing then changing back my video drivers
disabling pulseaudio and ubuntuone-sync (these were not installed in my previous, working setup)
looking at every relevant log file (mplayer, smplayer, demsg...) I know of
running ubuntu's testing utilities

I'm out of ideas. Going back to Jaunty is the only solution I'm pretty sure will work but it's not exactly ideal. It will be a few months at least before I'm able to install a completely new distro.

Playback problem "Sound Skipping"
https://bugs.launchpad.net/ubuntu/+s...0?comments=all

Workaround is to open:
/etc/pulse/default.pa

Find the line that looks like this and add "tsched=0".


change to
Then logout and back in.

Will this have any effect with pulseaudio disabled?

No, this file does not exist on my system.

Anyone else got any suggestions at all?

Make sure the cable is good.

Watch CPU usage, is it high when playing ?

Try a different I/O scheduler (deadline), try a different filesystem.

If you use JFS, use deadline.

The three cables seem fine.
I've tried to monitor CPU usage during playback but it's hard to predict exactly when the problem will occur and by the time I switch over to top it's too late. Is there a more useful alternative that shows CPU spikes over a period of several minutes?

I don't understand what you mean by an I/O scheduler. I'm using ext3 on all hard drives currently.

Maybe a graphical cpu monitor, like gkrellm, conky, or I think XFCE comes with one.

I/O scheduler manages disk access, and it is important which filesystem you use it with (at least for JFS).
http://en.wikipedia.org/wiki/I/O_scheduling