Video Speed Changer
Pick a playback speed from 0.25x to 16x to turn your video into slow motion or fast-forward, with unchanged audio pitch, exported as MP4.
Drop a video file here, or click to choose
MP4, MOV, M4V, MKV, AVI, WebM, OGV, TS, FLV, WMV, 3GP · up to 300 MB
Video Speed Changer
Video Speed Changer is a free online tool with 13 playback speeds — 0.25x, 0.5x, and 0.75x slow motion, plus 1.25x to 16x fast-forward — that turns any video into a slow-motion or time-lapse style clip, exported as a universally compatible MP4.
The audio speeds up or slows down with the picture, but the pitch stays natural — no chipmunk or booming voice effects. Everything runs locally in your browser with FFmpeg.wasm, so your videos are never uploaded to any server.
How to Use
- Upload a video file, up to 300 MB
- Pick a target speed from the list (0.25x–16x)
- Check the estimated output length, then start
- Wait while your browser processes the video locally
- Preview the result and download the MP4
FAQ
Are my videos uploaded to a server?
No. Reading, speed processing, and result generation all happen locally in your browser via FFmpeg.wasm — nothing is sent over the network.
Will the audio sound squeaky or deep after changing speed?
No. The tool uses the atempo filter, which changes audio tempo without shifting pitch, so voices still sound natural even at 0.25x slow motion.
Why does the frame rate look lower after fast-forwarding?
Fast-forward compresses timestamps into extremely high frame rates, so the output is sampled down to a compatible 30fps. When slowing down, frames are duplicated to keep a smooth 30fps with an accurate duration.
What is the 1x option for?
1x keeps the original speed but re-encodes the video into a standard MP4 (H.264 + AAC) — useful for unifying formats or fixing videos that some platforms refuse to play.
What format is the output?
Always MP4 (H.264 video + AAC audio), which plays on virtually any phone, computer, or platform.