Editing & Post-Production
Time remapping
Also called: retiming, speed change, slow motion in post
Time remapping puts speed on a curve instead of a single percentage, letting a clip start at 20%, ease up to 100% and hold there. Speed ramps in and out of a movement are the most common use, and matching a cut to a beat is a close second. Slow motion only looks right if the footage was captured at a higher frame rate, so a 24fps clip slowed to a quarter speed either judders or gets frames invented for it by optical flow. Shoot at 60 or 120fps when you know a shot is going to be slowed.