Possible duplicate Decoding of the AirPlay Mirroring protocol .
As explained here , the stream is basically encrypted using FairPlay ™, the same technology that encrypts applications and movies purchased through iTunes.
To do what you want, you'll need a FairPlay reverse engineer. This is the only way I can think that the existing applications you mentioned do this, but I'm not sure ... It would be interesting if someone could figure it out more. Despite this, it is not trivial.
Here is the protocol: http://nto.github.com/AirPlay.html
source share