Fast motion
Also known as: sped-up footage, speed up
Playing footage faster than it was recorded, used to compress an approach, a climb or a transit into something watchable.
Updated
What it means
Fast motion discards frames or plays them sooner. Either way the result is movement that reads as urgent or as comic depending on how far it is pushed. Nothing about the choice is neutral.
Moderate speeds are invisible. Doubling the rate of a long traverse looks deliberate; ten times over makes it a joke, and the two serve entirely different purposes in an edit.
A Time-lapse is the extreme version recorded in camera, while fast motion is normally a decision made on the timeline from ordinary footage. One is a capture mode; the other is an edit.
How it works in practice
Approaches are the obvious use. A chairlift ride, a hike to the top or a paddle out are Dead time at normal speed and tolerable at four times it. The journey still gets told.
Smoothness improves with source frame rate. Speeding up a High frame rate (HFR) clip discards frames evenly, where a 24-frame source starts to judder as soon as it is pushed.
Audio usually goes. Sped-up sound is unusable, so the section runs on a music bed and the original track is muted rather than pitched. A rising pitch reads as a mistake.
What to watch out for
Shaky footage gets worse. Speeding up handheld or mounted material multiplies every wobble, and Video stabilization has to run before the speed change rather than after. The order changes the result entirely.
Rolling shutter artefacts amplify too. A Rolling shutter skew that was barely visible at normal speed becomes an obvious warp once the frames arrive faster.
Overuse flattens an edit. A sequence where every transit is sped up turns the device into a tic, and a viewer stops reading it as compression and starts reading it as a style. Once per edit is usually the honest ration.
How RawClip handles it
Approaches and transits are usually dropped rather than sped up, since the goal is a short sequence rather than a complete account of the day. Where a transit matters for context, a brief shot of it carries the same information as a sped-up passage.