Change playback speed
Half-speed slow-mo to 4× fast-forward. Audio pitch is preserved.
drop a video here
or click to choose
About speed changes
This tool stretches or compresses the video time. The audio gets time-stretched the same way, so a 2× speed-up still has audible voices — just faster — rather than chipmunk pitch.
Extreme speeds (under 0.25× or over 4×) can produce audio artifacts. We chain multiple atempo filters internally to extend the range, but really slow / really fast speeds work better with no audio.
FAQ
Does the file get uploaded anywhere?
No. Open this page, turn off your wifi, then try a file — it still works. That's the test.
What's the maximum file size?
Browser memory is the limit. WebAssembly caps at 2–4 GB per file. Most laptops handle 1080p videos under a gigabyte comfortably.
Why is it slow on my phone?
FFmpeg-WASM runs on your CPU, not hardware video encoders. Phones have less CPU, so encoding takes longer.
Can I cancel mid-encode?
Yes. The Cancel button terminates the worker immediately. You'll wait a few seconds the next time you start.