I am trying to do the same for my app using qt and pulseaudio.

You can find the audio devices from the command line:
[You can modify a sample application http://0pointer.de/lennart/projects/...c-example.html

I believe there is some kind of policy in pulseaudio:
Have a look on
We need to find a way to mimic the configuration for skype or telepathy. But I am not sure what is the proper configuration?