Free Change Speed

Change Speed accelerates or slows video playback—time-lapse effects, fitting long demos into social limits, or slowing sports footage for technique review. Educators speed through silent setup steps, musicians practice along with slowed performances, and meme creators produce fast-motion clips.

Speed change alters duration without re-shooting, but audio pitch shifts unless corrected. The tool is popular for b-roll where sound is replaced anyway and for visual study where pitch-preserved speech matters less.

FFmpeg.wasm applies setpts filters for video and atempo or rubberband chains for audio to match the speed factor, re-encoding the result locally. Extreme slow motion may interpolate frames poorly compared to dedicated optical-flow tools.

Factors like 0.5× double duration; 2× halves it. Quality loss depends on re-encode settings chosen after speed adjustment.

Import the clip, choose a speed multiplier or preset such as 1.5× or 0.75×, and preview if available. Process and download the retimed video, checking whether audio sounds natural or should be muted and replaced.

Mute and add music for fast montages to avoid chipmunk vocals.

For instructional content above 1.25×, add captions because comprehension drops.