Since the aRts sound server used by KDE is running, it is using the sound device. If the server is idle for 60 seconds, it will auto-suspend and release it automatically.
Currently it doesn't suspend when using full duplex. Turn full duplex off from the KDE Control Center and it will suspend. Disabling full duplex is generally a good idea anyway if you only use aRts for playing audio and not recording.
Run them using the artsdsp. For instance, if you normally would run:
% mpg123 foo.mp3
% artsdsp mpg123 foo.mp3
This will redirect the sound output to aRts. This method doesn't require changes to the applications. It is something of an ugly hack however, and does not yet fully support all features of the sound card device, so some applications may not work.
You need a recent version of the glibc library; artsdsp will not work reliably on some older Linux® distributions. For instance, on Debian 2.1 (which is glibc 2.0 based) it doesn't work, while on Debian 2.2 (which is glibc 2.1.3 based), it does.
No. Using artsdsp can result in slightly more latency and CPU usage that using the aRts APIs directly. Other than that, any application that doesn't work should be considered a bug in artsdsp. The technique used by artsdsp should, if implemented properly, allow every application to work with it (including large applications like Quake 3).
You can wait for artsd to suspend or use the command artsshell suspend to ask the server to suspend itself. You will only be able to suspend the server if no aRts applications are currently using it, and no aRts applications will be able to run when the server is suspended.
If the server is busy, a crude but effective way to get rid of it is:
% killall artsd ; killall artswrapper Now start your own application. % kcminit arts
Any currently running aRts applications may crash, however, once you kill the server.
If you are running KDE1 applications, which output sound via the KDE1 audio server, you will need to run kaudioserver to make it work. You can start kaudioserver in the same way than other non-aRts-applications:
% artsdsp kaudioserver