There are a wide variety of radio interfaces available for PC's, and these are generally very simple to program. The biggest problem with supporting such devices is normally extracting documentation from the vendor.

The radio interface supports a simple set of control ioctls standardised across all radio and tv interfaces. It does not support read or write, which are used for video streams. The reason radio cards do not allow you to read the audio stream into an application is that without exception they provide a connection on to a soundcard. Soundcards can be used to read the radio data just fine.