For this year's DebConf, we (the video team) want to be able to use multiple cameras like at DebConf 5, where we had one for the projection screen and one for the presenter fed to an analogue mixer and a digitiser. At DC6 we had no mixer and no budget for one. Same at DC7 - unless we can do it with software. Toresbe had a go at writing one but didn't finish. I want to give it a go. So: