With Phonon the audio/video capture/output devices will be handled completely
transparent for the applications:

Applications can get a listing of available devices, show that to the user and
use the selected device on either AvCapture, VideoOutput or AudioOutput. On the
other hand the applications should use "the right defaults", so a central KCM
defines the defaults:

For every category a list of preference is created for devices. Devices that are
not available anymore (external USB headset that got unplugged) are still
displayed (with the name and description saved from the last time it was
announced by the backend) but marked as "currently not available" with an option
to remove the device permanently.

Use cases:
A)
- plug new audio device (headset)
- dialog asking the user whether he wants to configure KDE to use the new device
yes -> show audio device selection dialog
- user changes the device preference for the Communication category to prefer
  the new headset
- Kopete now uses the headset for voice-chat

B)
- headset got broken
- user looks at audio device selection dialog
- headset is shown as not connected
- user selects to remove the device

C)
- plug new webcam
- dialog asking the user whether he wants to configure KDE to use the new device
yes -> show video device selection dialog
- user changes the device preference for the Communication category to prefer
  the new webcam
- Kopete now uses the webcam for voice-chat