OneTaskBy Tim King · Updated
Video Speed Changer
Play a Video From 0.25x to 4x Speed, Keeping Pitch or Letting It Shift
OneTask is free, with no sign-up, and built by one person.
If this tool saved you time, a coffee helps keep new ones coming.
How the Video Speed Changer works
This video speed changer makes a clip play faster or slower and saves the result as a new file. Pick a speed from 0.25× to 4×, decide what the sound should do, press Render and download. The whole video is re-timed in your browser, so nothing is uploaded.
Speed is one of the simplest edits with the biggest effect. A 6-minute screen recording at 2× becomes a brisk 3-minute walkthrough. A cooking clip at 4× turns into a satisfying time-lapse. A goal, a trick or a pet's leap slowed to 0.5× becomes something people watch twice.
How the video speed changer works
The tool plays your video through the browser's own player at the chosen rate, draws each frame onto a canvas and records it with MediaRecorder. The recording runs on a normal clock, so a clip played at 2× produces a file half as long, and one played at 0.5× a file twice as long. The browser's audio engine changes the sound's speed at the same time, so lips and voices stay in sync.
Natural pitch or chipmunk?
Speeding up a tape raises every voice; slowing it down drops them into a growl. Browsers can undo that with time-stretching, which changes the tempo while holding the pitch steady.
- Keep natural pitch is right for talks, tutorials and anything with speech. At 1.25× to 2× voices stay clear and recognisable.
- Change with speed gives the classic effect: high, fast voices for comedy, or deep, slowed sound for drama.
At extreme rates, time-stretching starts to sound watery. Below 0.5× or above 2×, many editors remove the sound and add music instead.
What each speed does to length
| Speed | 1 minute becomes | Good for |
|---|---|---|
| 0.25× | 4 min | Sports technique, splashes, fast action |
| 0.5× | 2 min | Dramatic moments, dance breakdowns |
| 0.75× | 1 min 20 s | Following a fast tutorial |
| 1.25× | 48 s | Tightening talking-head videos |
| 1.5× | 40 s | Lectures and long demos |
| 2× | 30 s | Screen recordings, unboxing |
| 3× | 20 s | Process videos, crafts |
| 4× | 15 s | Time-lapse feel, setup and clean-up |
Slow motion and frame rate
Slowing a video down does not invent new frames. A 30 fps phone clip at 0.25× shows each frame for four times as long, so motion steps rather than glides. For smooth slow motion, film at 120 or 240 fps; the phone's slow-mo mode does this. Then slowing the clip spreads real frames out.
Tips and pitfalls
The render takes as long as the output. Slowing a 1-minute clip to 0.25× means a 4-minute render, because recording runs in real time. Trim first if you only need part of it.
Fast speeds can drop frames. At 3× and 4× the browser must decode three or four times the normal frame rate, and a weak laptop may skip some. That reads as natural time-lapse.
For playback only, you may not need a file. If you just want to watch slowly, the slow motion player changes the speed without rendering anything.
How to read the result
The stats show the speed used, the length before and after, what happened to the sound, and the new file size.
FAQ
How do I speed up a video without the voices sounding like chipmunks?
Choose "Keep natural pitch". The browser time-stretches the sound so it plays faster at the same pitch. Speech stays clear up to about 2×; beyond that, consider removing the sound.
Will slowing down a video make it smooth slow motion?
Only if it was filmed at a high frame rate. A normal 30 fps clip slowed to 0.25× will look jerky, because each frame is simply held longer. Clips filmed in a phone's slow-mo mode slow down smoothly.
Is my video uploaded?
No. The speed change is done by your browser's video player and recorder on your own device. Nothing is sent to a server, and the page keeps working offline once loaded.
Why does slowing down take so long?
The output is recorded in real time, so the render takes as long as the finished video. Halving the speed of a 2-minute clip produces a 4-minute file and takes about 4 minutes.
See also: all Video & Screen tools, Images, Audio, PDF, SVG, Simulations & Screensavers, Generative Art, Chart Makers, 3D Model Viewers, Drawing Pads, Mockups & 3D Making, Diagram Makers, 3D Science, Tracker Music.
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