Video Speed Changer re-times a clip anywhere between a tenth of normal speed and twenty times it. The video stream's presentation timestamps are rewritten and the audio is resampled to match, so a sped-up voice stays at a natural pitch rather than turning into a chipmunk. The audio filter only accepts a factor between 0.5 and 2.0, so extreme speeds are expressed as a chain of stacked filters — 4× becomes two 2× filters in sequence — which is handled automatically. Presets cover the common cases from quarter-speed slow motion to a 4× timelapse, and the new clip length is shown before you start. Everything runs on your device.
Features
Any speed from 0.1× to 20×, with presets for the common ones
Audio re-timed to match, preserving natural pitch
Automatic filter chaining for speeds beyond the audio filter's range
Option to drop the audio track entirely
Shows the resulting clip length before processing
Live progress with the option to cancel mid-run
Preview the result in the page before downloading
The video never leaves your device
How to use the Video Speed Changer
Drop a video file onto the box
Pick a speed preset, or type an exact multiplier
Decide whether to keep or drop the audio track
Press Change speed, then preview and download the result
Example
Input
A 2:00 clip at 4× speed
Output
0:30 clip, audio re-timed with two stacked filters
Beyond 2x the audio filter has to be chained, which the tool works out for you.
Common errors & troubleshooting
The audio sounds strange at very high speeds. — Time-stretching introduces artefacts as the factor grows, and chaining several filters compounds them. Above about 4× on speech, dropping the audio usually sounds better than keeping it.
Processing takes a long time on a long clip. — Changing speed rewrites timestamps, so the video has to be re-encoded rather than copied. Trim the clip to the section you need first if you only want part of it.
The output is larger than the source file. — The source may have used a more efficient codec or a lower bitrate than the H.264 encoding produced here. Run the result through the video compressor if size matters.
Entering 1x does nothing. — A speed of 1 leaves the clip unchanged, so it is rejected rather than spending time producing an identical file.
Frequently asked questions
Does speeding up a video change the audio pitch?
Not here. The audio is time-stretched rather than simply played faster, which keeps voices at their natural pitch. Playing a file faster without that step is what produces the chipmunk effect.
What speed makes a good timelapse?
It depends on the subject. 4× to 8× suits walking or traffic; clouds and construction want far more, often 30× or beyond, which is usually better achieved by shooting fewer frames than by re-timing an existing clip.
Can I create slow motion from a normal video?
You can stretch it, but you cannot invent frames that were never captured, so a 0.25× clip shows each original frame four times and looks stuttery. True slow motion needs footage shot at a high frame rate.
Why does the video have to be re-encoded to change speed?
Because every frame's presentation timestamp changes. A stream copy preserves the original timing data by definition, so re-encoding is unavoidable — which is why the process takes real time rather than being instant.
Is my video uploaded to change its speed?
No. The clip is processed by a video engine running inside your browser tab, so the file stays on your device throughout.
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