Reading the RC input values to control the Raspberry Pi

And another question.
Is there a way to read the RC input values, while APM is running?
I would like to start/stop recording of the raspicam via a switch on my Taranis and do other things perhaps

I’m not sure of the exact way to do this, but probably it is possible to read RC input value using mavproxy. GCS is able to receive those values, so there’s got to be a message that carries that information. --master tcp:
port 5770 seems to be the comms port to connect to

I may have been wrong, 19550 seems more common