XVideo on VGA laptop output with radeon driver

I’ve been doing a lot of playing with MythTV using Mythbuntu. One of the nice things it supports is diskless booting of frontend systems so I thought I’d try it out on my old laptop. It worked quite nicely until I was about to start displaying any video through the VGA output to our TV, then you’d get a blue screen rather than the video but the video would display quite nicely on the laptops own display. Needless to say that was pretty suboptimal. 😉

The reason that happens is that with the free ATI Radeon driver in Ubuntu the XVideo overlay is assigned to the first display (the built in LCD) even if you’ve disabled it through the XRandR config in your xorg.conf file. I tried a lot of mucking around with various Xorg settings and got nowhere until I stumbled across the rather simple solution!

The xvattr package is in Universe in Ubuntu and I make it happen each time by putting the command into the /etc/mythtv/session-settings file (just can just create it if it doesn’t exist, it just gets sourced by the mythfrontend command on startup).

Sadly I don’t think I’m going to be able to use the laptop after all because it doesn’t have line out, just headphones, and that doesn’t appear to be enough for my amp. 🙁