I ran into this issue last night when I made a matte with a rotobrush. Everything looks perfect when I scrub through and even go frame by frame, but when I export it I get this issue where there seems to be "extra" matte that is cutting off something in the scene by putting the background on top of it (this is what the intentional matte is supposed to do, but not in the frames where it keeps showing up).
I'm using AE CS6 (trial version) with the latest updates. The source footage is h264 (originally AVCHD intelaced, deinterlaced using premiere pro before importing into after effects). The output is h264. Has anyone seen this before? and can you offer any advice on what to check?
Other possibly important info is that there are 3 different rotobrush mattes on 3 different layers. One covers everything, another covers things half way "through" the scene (3D), but gets covered by closer things, and the last one is for when the camera gets to the other side of the subjects.
So far I've checked:
-The matte itself.
-Made sure I drew the matte with the rotobrush at full res.
Any quick help would be greatly appreciated because the deadline for the video I'm working on is tonight. (Sept 12th).