Thursday, December 24, 2009

M-Audio / Freebob and Ubuntu 9.10

In setting up a new Ubuntu 9.10 install with ubuntustudio, I had to do a few manual things. There is an UbuntuStudio distribution, but I typically opt to install what I need later, which is generally just the awesome audio stuff. If you go this route and want to use jack, be sure to also install the real time kernel.

sudo apt-get install ubuntustudio-audio
sudo apt-get install linux-rt

I use a M-Audio FiewWire Solo audio card and have used the freebob driver with success in the past. I was happy to see that it is installed by default now with qjackctl. But when I started jack initially I got errors suggesting the driver was not loaded. I had to install the driver and change permissions before I jack would start up.

sudo modprobe raw1397
sudo chmod a+rw /dev/raw1394

Chmod was transient however, and after rebooting /dev/raw1394 didn't have the correct permissions. I added a file called 40-permissions.rules and gave the audio group permission to access the device. I failed to mention earlier that I also had to add my personal user to the "audio" group before getting jack to start up.

sudo vim /etc/udev/rules.d/40-permissions.rules
# EEE1394 (firewire) devices
KERNEL=="raw1394", GROUP="audio"

So I was done right? No. After reboot I still didn't have permission to access the firewire device. ls told me why.

ls -altr /dev/raw1394
crw-rw---- 1 root video 171, 0 2009-12-24 19:55 /dev/raw1394

I guess by default /dev/raw1394 belongs to the video group. Well my user doesn't, and I'm not using firewire for video, so I switched it to belong to audio.

dextron@dextron:~$ sudo chgrp audio /dev/raw1394
ls -altr /dev/raw1394
crw-rw---- 1 root audio 171, 0 2009-12-24 19:55 /dev/raw1394

After another reboot, all is well. I'm wondering if I should have just left the group as "video" and added my user to the video group plus changing my udev rule (to use video instead of audio). I suspect there is no single right answer, but if you have any insights, please leave a comment. Thanks!

1 comment:

MKaslan said...