Change the speed of a video
Make a video or a recording faster or slower, preview the result right away, and keep voices sounding natural.
Sealed on this device
Runs in your browser. Nothing is uploaded.
Sealed
Your video or audio
Your browser can’t play this format, but the file can still be processed.
Result
- Original
- New file
- Saved
How it works
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Add your file
Drop a video or an audio file, or choose one from your device. It stays in your browser.
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Choose the speed
Move the slider or tap a common speed. The player plays at that speed so you can check it before saving.
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Save the result
Start the processing, follow the progress, then download the new file.
Frequently asked questions
Is my file uploaded to a server?
No. Everything runs in your browser with a WebAssembly version of FFmpeg. Your video or recording never leaves your device.
Will voices sound high-pitched when sped up?
No. The sound is stretched or squeezed in time without changing its pitch, so voices keep their natural tone, even at 2× or 0.5×.
Which speeds can I choose?
Anything from 0.25× (four times slower) to 4× (four times faster), to the hundredth. 1.25× to 2× is popular for lessons and talks, 0.5× for slow motion.
Does slow motion look smooth?
The tool slows down the frames that exist; it doesn’t invent new ones. A video filmed at a high frame rate, such as 60 or 120 frames per second, gives the smoothest slow motion.
What format do I get?
Videos are saved as MP4 (H.264 and AAC), which plays everywhere. Audio files keep their format when it’s MP3, WAV, FLAC or OGG, and are saved as M4A otherwise.
Which open-source software does this tool use?
It uses FFmpeg compiled to WebAssembly by the ffmpeg.wasm project. Its core is licensed under the GPL, and its full source code is available from that project.