Preparing Your System for Audio Work

Obviously, the first step is to install a soundcard. You don't have one? Well, go get one! And make sure it works with Linux. I won't cover installing the kernel drivers and installing the new kernel; these procedures are discussed elsewhere in the book (see Chapter 1 ). However, when installing a soundcard for the first time, you might run across a nonobvious problem. You can verify that the kernel drivers are installed and loaded correctly by checking the output of dmesg for a soundcard- related entry:

es1371: version v0.30 time 19:26:05 Oct 5 2001

es1371: found chip, vendor id 0x1274 device id 0x1371 revision 0x08

es1371: found es1371 rev 8 at io 0x9400 irq 5

es1371: features: joystick 0x0

ac97_codec: AC97 Audio codec, id: 0x4352:0x5913 (Cirrus Logic CS4297A rev A)

But even if the drivers are installed correctly, you still need to have device files set up so your applications can communicate with the drivers. On some distributions those files are not installed by default or are installed with incorrect permissions. To fix this, you can run the following commands:

# cd /dev

 # ./MAKEDEV audio

 # ls -l /dev/audio

 crw-rw---- 1 root audio 14, 4 Oct 17 21:37 /dev/audio

 # adduser myself audio

The MAKEDEV command creates the character devices in /dev that are necessary for communication with the soundcard drivers. Then we verify that the permissions are correct; we want the device file to be owned by root and to be readable and writable by members of the audio group. Finally, we add nonprivileged users to the audio group .

If this setup isn't done, either manually or by a distribution's installer, it can be quite maddening trying to track down why the soundcard doesn't work. You may be tempted to recompile the kernel a half dozen times, or even try exchanging the card for a new one. It seems whenever you have a problem with Linux, the solution turns out to be simple. It often turns out to be obscure, as well.