Setting up JACK on Fedora 12

Audacity is somewhat of a broken joke these days, so I needed to use Ardour to record. And that meant setting up JACK. Since JACK insists on exclusivity, I also needed to route pulseaudio through JACK so I could use other apps at the same time. Unfortunately, this is a bit of a pig to figure out. I hacked it as follows:

First edit /etc/pulse/default.pa, you need to add two lines:

load-module module-jack-sink
load-module module-jack-source

In theory now, a restart of pulseaudio should start using JACK for recording and playback, if jackd is running. However, it tends not to work very well: you might find PA hanging and you have to kill -9 it.

This isn't enough of course, now when you log in again, gnome-session will try to start pulseaudio, but not jackd, so nothing works. It's far from the right way, but I edited /usr/bin/start-pulseaudio-x11 (which is started from a /etc/xdg/autostart/ script), as follows:

amixer -c 0 sset 'Input Source' 'Line'

nohup jackd -d alsa &

sleep 5

/usr/bin/pulseaudio --start "$@"

Note that I have to set the input source by hand: something in desktop start up used to do this for me, but now I'm going through JACK it has to be done by hand.


Jonathan Wakely said...

That's probably why I haven't been able to get Ardour working - ta!

Dang, if I knew that last week maybe I wouldn't have decided to buy another sampler/sequencer. But I probably would have done anyway.

John Levon said...

Two tips for Ardour, as it's a little confusing:

* you want to set Options->Monitoring->Ardour does monitoring in order to hear input

* you probably want to disable "Auto input" (near top right) so you only hear input when recording is running

* you need to create a track, then enable it as a recording track by clicking the record button on the track itself (not the master one at the top)

Jonathan Wakely said...

wow, Audacity really is broken. I'm used to it hanging when I try to play a new loop without stopping the old one, but the compressor effect just took down my X server! I can't be bothered configuring Ardour right now so I'm going to stick to hardware instead of buggy software.