Chroma Key Live is a free tool to generate a live green-screen composite (AKA "chroma key") during a video shoot. In the days of analog video, the camera’s live signal was routed through a keyer in the control room and delivered back to an on-set monitor. This way, the production team could see exactly how the actor looked when composited over the background image. Modern digital video is shot without the support of an analog studio, so the chroma key is created afterwards inside the computer.