I got some footage that was in a codex that after effects didn't accept so when I converted it to a useable format it came out as 1440X1800 (1.33) I'm very much a noob at converting and compression type of stuff so this already might be the problem I donno though. But I put that footage into AE and when i use key light my subject becomes terrible noisey/grainy so much that it looks like he has static just running through him. My question is did I mess it up in converting. Also how would I fix the noisey ness in AE
We don't know what codecs you are using, that might change the answer.
That being said even with good footage I will get grainy footage when apply keys in AE. What I do get the best key I can without worrying about grain(garbage mattes, multiple keys-if necessary). Then I place that keyed footage over the original footage and just change it's track matte to alpha matte.
Johnny Cuevas, Editor
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.