I've seen a few audio visual equipments that can be controlled with both wired (3.5mm stereo jack) and wireless (infrared). On the equipments, there are IR receiver port and also a port that resemble audio in port used for wired remote control.
On the remote control side, it also has both IR transmitter and 3.5mm port.
I have no problem deciphering and emulating the infrared code that the infrared remote generates but I am wondering how does the 3.5mm jack control works. Is there any standard or protocol for this or does each manufacturer creates their own?
How do I capture the stuff sent from 3.5mm port of the remote control to the equients? Any idea?