I have some video of testimonials where I have several seconds of the backdrop before the subject enters the view. When I use Adobe Audition for cleaning up audio, I can select a few seconds and treat that as "Background Noise Print" and remove that from the audio, is there a way to do something similar with After Effects? I would love to set those first few seconds as the "Background" and then anything that changes is automatically the foreground.
IF (big if) there is absolutely no noise or compression artifacts in the video and no camera movement you can sometimes use Effects>Keying>Difference Matte to remove elements added to the shot by using a freeze frame or looped section of the "background" as the Difference Layer. Difference matte will remove all pixels that are the same in the difference layer and the source layer. If the camera moves or the wind is blowing things around or the light changes then you are out of luck.
Other than that you have to roto by hand or try Rotobrush.
Thank you so much, I will give that a try. I was shooting indoor with no camera movement while filming and lighting should have been stable as well.