Video speed changer
Choose a video, pick a speed between 0.25x and 4x and record a new file at that speed. The length changes by the inverse of the speed. Sound can be kept or dropped.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose a video file.
- Set the Speed with the slider, the number box or a preset button.
- Check the new length, then press Change speed.
- Preview the result and download it.
How it works
The video is played at the chosen playback rate into a canvas while the canvas, and optionally the sound, are recorded. Recording at 2x therefore takes half the original time, and at 0.5x twice as long. The speed is limited to 0.25x to 4x.
Worked example
A 90 s clip at 1.5x lasts 60 s. A 30 s clip at 0.5x lasts 60 s.
Tips
- Very slow speeds repeat frames, so motion looks less smooth than the original.
- Cut the clip down first with the video trimmer if you only need part of it.
Frequently asked questions
How is the new length calculated?
The original length divided by the speed: 60 s at 2x becomes 30 s, and at 0.5x it becomes 120 s.
Does the sound pitch change?
The browser normally keeps the pitch of speech and music when playback speed changes, so voices do not turn into chipmunks. At extreme speeds the sound can be rough or choppy; untick Keep the sound if you do not need it.
Why does it take as long as the video?
The browser has no built-in way to convert a video file, so the tool plays the clip into a canvas and records the canvas with MediaRecorder. That happens at playing speed: a 1-minute clip takes about a minute (half that at 2x speed). Keep the tab open and visible, because browsers slow down background tabs.
Which file format do I get?
WebM in Chrome, Edge and Firefox, which can be played by those browsers and most players. Safari records MP4 instead. The original format is not kept, because the clip is recorded again from the picture the browser shows.