I've got a hauppauge TV capture card in my linux box and I'm frequently capturing stuff. I also do most of my transcoding on the same box and I've noticed occasionally when I transcode, it screws up the captures. I suspect it's just not getting the CPU time it needs and its buffer is overflowing.
To try to fix this, I've set the priority of the capture process to -10. I already had the transcoding operating at +15. I have some other stuff running at +19 that I want the transcoding to have more priority than.
My question is, I really don't know a great deal about how Linux handles priorities. Is -10 high enough for the TV capture card? It hardly uses any CPU, honestly. I just don't want it to hiccup when it does need it. Would it be okay to set it to -20?