I must say that there are some examples in Google, but most of them won't work with current GStreamer/Farstream releases (0.10 at the time I'm writing this, 1.0 is about to be release) as they're too old. There is some documentation, but I'd say some descriptions, explanations and how-to's are missing. (inline edit: I started writing this post in September 2012, we're in April 2013, 1.0 was released and docs have been improved a lot, last statement is not valid anymore).
Anyways, after a few days I managed to get all the demos that I wanted to do before the actual VoIP software. Those are the typical one-liners for:
- send the microphone signal to the speakers
- send the build-in camera signal to the frame-buffer
- send both the microphone signal and the built-in camera signal to the speakers and the frame-buffer
- play audio from a file to the speakers
- play video from a file to the frame-buffer
- play both audio and video from a file to the speakers and the frame-buffer
- record from the microphone to a file
- record from the build-in camera to a file
- record from both the microphone and the build-in camera to a file
I uploaded the code to GitHub, you can get it from here, just keep in mind that this is a work in progress. I'll try to develop as many examples as possible and support both 0.10 and 1.0 versions of GStreamer.