Change Video Speed
Choose a video and a speed from 0.25× (slow motion) to 2× (fast); the audio keeps its pitch and the result is re-encoded in the original format.
- Runs in your browser
- Free to use
About this tool
Change Video Speed re-times a clip from 0.25× to 2× in your browser: slow motion for analysis, fast forward for long recordings. FFmpeg adjusts the frame timing and stretches the audio while keeping its pitch, then re-encodes to the original container.
Related: Video Cutter, Loop Video.
How to use it — quick steps
- 01
Add the video
Drop an MP4, WebM or MOV file on the dashed area or choose it; a preview player appears below it.
- 02
Pick the speed
0.25× and 0.5× for slow motion, 1.25× to 2× to shorten lectures, tutorials and screen recordings.
- 03
Press "Change speed"
FFmpeg re-times the frames and stretches the audio in your browser; play the result and download it.
Key features of this tool
Pitch preserved
The audio is stretched with the atempo filter, so voices stay natural instead of becoming chipmunks or growls.
Original format kept
Re-encoded to H.264/AAC (VP8/Opus for WebM) in the same container as the source.
FFmpeg in your browser
The real FFmpeg, compiled to WebAssembly and loaded on first use (about 30 MB, then cached); files are processed locally and never uploaded.
Frequently asked questions
Does 0.25× look smooth?
Frames are shown longer rather than interpolated, so very slow speeds look stepped on fast motion; 0.5× is usually smooth enough.
How long does the output last?
Duration divided by the speed: a 10-minute video at 2× becomes 5 minutes.
Why is the first use slow?
FFmpeg (about 30 MB) is downloaded the first time and cached; after that it starts in a second or two. Encoding itself runs on one CPU core, so long videos take a while.
Are my files or data uploaded?
No. The tool is plain JavaScript that runs in your browser; the files or data you provide here are never uploaded to our servers.