Why pitch correction matters
The naive way to speed up a video is to play frames faster, which also pitches the audio up — that is the chipmunk effect. Naive slow-motion has the opposite problem: the audio drops into a Darth-Vader register. We use FFmpeg's atempo filter, which decouples speed from pitch. Voices stay at the same frequency, words just arrive sooner or later. The result sounds like a normal podcast running at 1.5×, not a cartoon.
When you would actually use this
Three common cases: trimming a long meeting recording down to half-length so a teammate can speed-watch the highlights; compressing a 5-minute walkthrough into 2 minutes for a tighter doc embed; or slowing a UI demo to 0.5× so a viewer can see exactly which button you clicked. Speed-up is the more common request — most screen recordings are over-padded and a 1.5× export is more watchable than the original.
Speed in the player vs speed in the file
Most video players let viewers change playback speed on the fly. If you control the playback surface, that is almost always the right answer — the file stays small and viewers pick their own pace. You only need this tool when the destination does not have a speed control: a Slack inline player, a CMS embed without UI, an email attachment, or a file someone will scrub through frame-by-frame.
Recording at the right pace from the start
If you record on Clipy, the player has built-in speed controls (0.5×, 1×, 1.25×, 1.5×, 2×). Viewers can pick their own pace and the original file stays compact. This tool is for the cases where you need a permanent change baked into the file itself.