This is something most more experienced gnome users will know, but today I could actually help somebody with it. So I will do a short writedown:
The volume up/down button on the keybord controls the Master mixer, but on his system this didn’t work, so he wanted to control the PCM mixer.
The obvious solution:
Change the mixer gnome adjust, but I (and a few others) didn’t know how todo this.
From the Keyboard Shortcut editor of gnome write down the keycode for volume up/down. Then remove them. (we want the keys unbind for now).
In my case this was something like:
Volume up: 0xb0
Volume Down: 0xae
Now start gconf-editor
edit the run_command_1 and set the value to 0xb0
edit the run_command_2 and set the value to 0xae
Now goto /apps/metacity/keybinding_commands
edit the command_1 and set the value to ‘amiser sset PCM 10%+ on’
edit the command_2 and set the value to ‘amiser sset PCM 10%+ on’
(you can find amixer in alsa-utils package)
Now you should be able to control the correct mixer from your Volume keys on the keyboard. (in steps of 10%, but this can easily be changed).
I have nothing against gconf, but it is slowly becoming a huge dump of unknown (yet often useful) program options. If I run a clean system, I spend several minutes in gconf-editor tweaking some small stuff to fits my needs. Normal/new users won’t need todo this but maybe some UI guru’s could give gconf-editor a bit easier to access interface.