I would like to be able to do a down and dirty live chroma key while on set to check angles against a background plate on my computer. any suggestions on software only or software/hardware packages that can do this and not cost a fortune? I really don't care if it's a clean key or not. as long as I can see the bg plate through it to verify the camera angle and lighting. I don't want to have to grab a still, take it into another program, etc. I just want to look at my laptop screen and verify that the shot matches the BG Plate.