Well, there is so-called "HD Radio" (https://en.wikipedia.org/wiki/HD_Radio) which is digital, the only problem there is that I know of no software-operated digital tuners that will bring it into a PC (something like a HDHomeRun, but for HD Radio). In fact, it looks like this technology never really caught on for anything other than automotive radio receivers.
I'm never quite sure how the pipe:// support works. I would really like to see an example of taking an audio or video stream from the Internet and using pipe:// to bring it into TVHeadend so it would be seen as a channel. Obviously it would need to be a streaming source for this to work, but the goal would be to be able to use the PVR functionality of TVHeadend to record certain types of scheduled programming, so that it can be played back later. I believe Kodi can support playing of certain types of streaming material natively, as can VLC, but neither has the ability to select and record a stream on a schedule. An example would be recording a particular program from a local NPR station for playback later in the day.
Another reason for this would be if you wanted to have multiple computers or devices playing the same stream (live or recorded), in which case TVHeadend could access the stream once and distribute it to all the other devices, in order to save bandwidth.
