Is it possible to render out keyed green screen footage and still use the transparency? I feel like it takes up so much ram to put your background behind your subject WHILE your keying effect is active. It would be great to separate the two tasks and render out a pre-keyed version of your forground footage first, before messing with the bg.
Maybe I am doing something wrong in terms of keeping ram usage to a minimum when it comes to green screening.
This is indeed possible. You must solo the keyed layer(s) and choose an export codec that supports transparency, such as PNG, Animation, or ProRes 444 (hopefully you are using the Render Cue). And then be sure to choose "RGB+alpha" in the "Channels" dropdown in your Output Module Settings. I tend to use PNG since it is a lossless codec with a much smaller file size. However, it really depends on the project and quality of source footage. PNG doesn't support 10 bit color, for instance, but may be perfect for a DSLR project.
Definitely look into optimizing your RAM settings. Unless the comp is fairly complex, I don't see why a key would slow you down too too much.
As it was mentioned you could render out a matte sequence or the footage with an alpha, however that will not eliminate the tweaking you will need to apply for the compositing process. Unless you have a really old machine, you should be able to handle two layers. If you have multiple objects/actors that need to be composited in the same shot, do one at a time and render lossless in between.
[jeremy freeds]" I feel like it takes up so much ram to put your background behind your subject WHILE your keying effect is active. It would be great to separate the two tasks and render out a pre-keyed version of your forground footage first, before messing with the bg. "
Why do you think this? Generally speaking, Ae can easily handle hundreds of layers. Are you having some kind of problem? What are your system specs and memory & multiprocessing settings?
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