It is up to the OS, which will usually do a very good job of it.
You can however change it using nice, by changing your start up script to something like this
- Code:
nice -n -5 /path/to/serviio/bin/serviio.sh
Alternatively, if you just want ffmpeg which deals with transcoding to have a high priority, then write a short ffmpeg wrapper script that calls the real ffmpeg using nice to adjust its priority.
However, my approach is the oposite, I run anything that may take CPU time, but I don't care about, with a lower than normal priority.