PRIVATE BROWSER PROCESSING
Speed a video up or slow it down without losing sync
Choose 0.5×, 0.75×, 1.25×, 1.5× or 2×. The tool changes video timing and adjusts audio timing too when an audio track is present.
Video speed changer
Changing speed is really two timing problems: picture and sound
Audio tempo correction is applied between 0.5× and 2× so speech stays closer to its original pitch. If a file has no usable audio stream, the tool still creates changed-speed video without audio.
Privacy and limitations
Processing uses FFmpeg WebAssembly locally. The video is not uploaded by this tool. Closing or refreshing the page clears the working file. Speed depends on the browser, device memory, source codec, duration, and resolution, and tools that re-encode are not lossless.
Common questions
Which video formats are supported?
The FFmpeg core handles common formats such as MP4, MOV, WebM, MKV, AVI, MPEG, M4V, 3GP, TS and WMV, though the browser may not preview every format.
Is my video uploaded to DJAI?
No. The source file is read and processed in your browser on your device.
Why can the first run take longer?
The browser downloads an FFmpeg WebAssembly core of roughly 31 MB the first time processing is needed; caching can help later runs.
BUILD WITH DJAI
Want to build a tool like this one?
This tool runs entirely in the browser. Explore DJAI Academy’s practical building courses.