[jitter] mixing 3 live video sources and a movie?

Hi Everyone,

Apologies for another newbie question, but I'm abit stuck. I'm trying to write a simple patch that will allow me to mix three live video feeds  (using 2 unibrain firewire cams and one built-in webcam) with one or two movie files, also allowing me to apply various fades between them, effects, math operations etc.

What I'm unclear about is what is the difference between using the jit.lcd-layer vs using multiple jit.gl.videoplanes? And if I want to use the jit.op object to use different math operations for mixing, is there a way to combine these (ie. it's only got 2 inputs...so how would I apply this for each video source?)

Sorry if these are painfully obvious. I've searched the forum but that's where I ended up with the above questions.

Thanks in advance,

Bill