Microphone menu should not show virtual sources
Submitted by Arun Raghavan
The empathy-call mic menu currently enumerates all sources (except monitor sources). We should also filter out virtual sources (that is, things that don't have the PA_SOURCE_HARDWARE flag). The rationale here is that, IMO, users should not be aware of these sources.
This raises the question of how we should handle the fact that when moving a stream to a sources that causes the echo-canceller to be loaded, the stream will automatically get moved to a virtual source.
The echo canceller virtual source has a property called "device.master_device" which can be used to find the device being echo-cancelled. Ideally, this should be traversed till we find a source without this property and this is the real master source.