Here's something to get you started on that. Haven't tested it myself yet, though 
There's also this, but I never managed to get it working.
There's also this, but I never managed to get it working.I tried that audio stuff. Didn't work out for me.
So I went back to QR codes.
QtQR doesn't work because there's too much information in a QR code with a whole Armory transaction and the webcams couldn't focus well enough on it. Dividing the transaction data up manually to multiple QR code would have been very tedious.
Instead, I found and used this software which automates the process: https://github.com/anderson-/Eye-Fi It actually worked! I'm going to write a tutorial on it soon.
Neither of those systems worked for you? Newar said the audio system he recommended still works for him...
I have exactly the same issue as you with webcam focusing and reception of the whole QR code. I'm not sure what webcam do you use, but I'm using an old PS2 Eye Toy webcan I had around. It's actually the only "webcam" I've ever had
it only has 1mpx, I think, so I usually divide the transaction info over several QR codes... I guess I'll just have to get an official Raspberry Pi camera sooner or later, 5mpx will definitely improve things.The software you linked seems quite nice... Things to consider when I finally decide to improve my offline system.
