Change video speed
Speed it up or slow it down, anywhere from a quarter of the pace to four times it. The sound follows.
- Free
- Runs on your device
- No account
- No limits
One file at a time. The video is edited on your own device, so nothing is uploaded and there's no size limit beyond what your browser can hold.
How to change video speed
- Drop a video in the box above.
- Pick a speed. Above one is faster and shorter, below one is slower and longer.
- Download. The file keeps its name and its format, with -speed added.
- The first video also fetches the video engine, about 7MB, which your browser then keeps. After that it starts straight away.
About changing video speed here
The picture and the sound are moved together, so a clip at double speed is half as long and still in sync. The sound is stretched rather than resampled, which keeps voices recognisable instead of turning them into chipmunks, though a large change is always going to be audible.
The filter that stretches audio only accepts a change between half and double, so anything beyond that is applied more than once. Quarter speed is two halvings and quadruple is two doublings. Without that the sound silently comes out wrong, which is the kind of bug that gets shipped because the picture looked fine.
This edit changes the picture, so every frame has to be decoded and encoded again. Your own machine does that work, which is what keeps the file off anybody's server, and it's why a long clip takes longer than a short one. Trimming and removing the sound are the two things here that skip it entirely.
Common questions
Is the change video speed free?
Yes, properly free. No paid tier, no trial, no watermark on the result and nothing to sign up for. Put as many files through it as you like, as often as you like.
Are my files uploaded to a server?
No. The change video speed runs inside your browser, on your own machine, so your files never go anywhere. Big ones are fine too, up to whatever your browser can hold.
Does changing the speed make the audio sound wrong?
Less than you would expect. The sound is time stretched rather than simply played faster, so the pitch stays where it was and a voice still sounds like that person. A small change is close to unnoticeable. A big one, like quarter speed or four times, does leave an audible artefact, which is why a lot of slow motion clips drop the sound entirely.
Can I make a timelapse from a normal video?
Yes, by speeding it up. Four times is the fastest single pass here, so an hour of footage comes down to fifteen minutes. For a stronger effect, run the result through again. Pairing it with a lower frame rate helps as well, since a timelapse doesn't need sixty frames a second and dropping them makes the file considerably smaller.