Not sure where to ask this as it could possibly be a number of things, but since I'm doing all keying in AE...
Gh2 (AVCHD) footage (.mts files)
Transcoded via 5dtoRGB into ProRes 4:2:2 with 709 / progressive / broadcast range / 1.0 gamma settings
Keyed in AE cc2014 using either keylight or Primatte. Same problem with both.
Basically, the footage looks fine before keying, but after keying, no matter what I do, the foreground is ridiculously grainy. No matter how much I zero in on the combined matte to make sure it's pure opaque in foreground, I get this same drastic grain.
My first thought is the footage. It's a bit confusing with gh2 since it doesn't do 1080p without being hacked, hack allows it, but it doesn't show you anywhere that it is in fact doing progressive. After being transcoded in 5dtoRGB, though, I'm setting it to progressive output and it looks fine before keying, so that seems like a dead end.
I've tried a dozen settings, but no matter how opaque I make the foreground, the issue persists. I know there is a known iso bug with this camera, but what's confusing me is that the footage looks smooth and noise-free prior to keying.