How to speed up a video
- Add one or more videos; each clip starts at 2x speed.
- Select a clip and change Speed if you want another value.
- Trim or split the clips on the timeline if needed.
- Choose MP4 or WebM and select Export video.
Worked example
A 10-second clip at 2x lasts 5 seconds on the timeline, and at 0.25x it lasts 40 seconds; these lengths are checked in the editor's unit tests.
Formats and limits
| Input | MP4, MOV, WebM, MKV |
|---|---|
| Output | MP4, WebM |
| Limits | The export is built in memory, so very long or high-resolution projects may fail on devices with little RAM. Needs a browser with WebCodecs (current Chrome, Edge, Safari 17+ or Firefox 130+). Other browsers are told so before any work starts. |
| Engine | Mediabunny decoding → canvas compositor (crop, rotation, letterboxing, fades, text) → WebCodecs encoding; audio decoded, retimed and faded in a Web Worker |
Limitations
- The pitch of the sound rises with the speed; there is no pitch-keeping option.
- Speeds are fixed steps, so values such as 2.5x are not available.
- The export is built in memory, so very long or high-resolution projects may fail on devices with little RAM.
- Needs a browser with WebCodecs: current Chrome or Edge, Safari 17 or later, or Firefox 130 or later. Other browsers are told so before any work starts.
Questions
Does speeding up a video change the sound?
Yes. The sound speeds up with the picture and its pitch rises, like a tape played faster. Mute the clip if you prefer silence.
How long will the sped-up video be?
The clip's length divided by the speed: a 60-second clip lasts 30 seconds at 2x and 15 seconds at 4x.
Can I slow a video down instead?
Yes. The Speed list also has 0.75x, 0.5x and 0.25x.
Privacy
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