Set Scale & Position Keyframes cause animations to happen 1 frame slower than programmed.

I've set some very specific, frame-perfect keyframes for animations in videos. Video elements that scale, rotate, and crop at exact measures. However, the program moniter shows the animations happening exactly 1 frame slower than expected. It doesn't matter if the keyframes are set 5 frames apart or 500, it always adds just 1 frame to the animation. Does anyone else have this problem, and know what I can do to solve it?