Selecting Audio device for libvlc-gtk in linux

[nmanbamboo1980]

Hello all.
I have just used the GTK wrapper for LibVLC. This library allows you to use libvlc from C code in a GTK interface with GTK widget representing the player.

http://code.google.com/p/libvlc-gtk/

The application works very well, audio and video both.

Now I have a PC running Linux (Arch) which has two sound cards
1) onboard
2) Usb sound device
Both of these get detected if I run the command $aplay -l

Right now the application uses the onboard sound device.
My question is how do I force the application to select the USB sound device?