I exported a clip from FCP (ntsc, 720X780, 29,97fps) to AE because I needed to do some time remapping. The trouble is, after I slow down a segment of a shot, the image is unstable (it keeps on jumping faintly but rapidly). It's obvious on the top and bottom edges of the image (it was shot squeezed to be letterbox). In fact, I don't know if the image jumps or just the letterbox bars. Any clues?