Free tools › Audio and video

Change video speed

From half speed to four times, the sound stretched without the chipmunk effect.

This one runs on your credits. From half speed to four times, the sound stretched without the chipmunk effect.

Sign in and get 500 free credits every month — enough for many files — then drop the file in the workbench and run change video speed there.

Pick a file below to see exactly what it would cost.

More free conversions, where you upload. The Fylane extension does the same work inside any upload form, on its own free share every day.Add to Chrome

How to change video speed

Sign in — 500 free credits a month.
Drop the video in the workbench.
Run it and download the MP4.

What happens to your file

The frames are retimed (setpts) and the sound is stretched by the same factor with its pitch preserved (atempo, chained past 2×), then written as H.264 and AAC in a faststart MP4. At 4× a minute becomes fifteen seconds; at 0.5× frames are repeated, so fast motion looks stepped — true slow motion needs a high-frame-rate source.

Media processing costs real compute per minute, so it runs against your own credits, the first 500 each month free.

Questions

Why does 0.5× look jerky?

Frames are shown twice as long, not invented. A clip shot at 60 fps slows smoothly to 30; a 30 fps clip steps.

Do it once, not on every form

Fixing a file here means downloading it and going back to the form. The Fylane extension does this work inside the form instead, on the file you already have.

And it keeps the result. The next application that asks for a résumé, a cover letter and a photo fills all three from one tap, each one refitted to what that site accepts.

Your files stay in the browser, encrypted, on your machine. Nothing is uploaded to keep them and nothing is sent anywhere to fill a form.

Filmed from the extension: three upload fields on a job application, filled from one tap.

Add to Chrome — free What it does

Do this in code

curl -X POST https://api.fylane.dev/v1/jobs \
  -H "Authorization: Bearer $FYLANE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "file_id": "<file id>",
    "operation": "video.convert",
    "options": {
      "speed": 2
    }
  }'

The same operation, video.convert — Anything playable becomes H.264+AAC in a faststart MP4 — or, by `container`, MOV, MKV, VP9+Opus WebM, or Xvid+MP3 AVI for old players. Plus the small edits: mute, rotate, flip, speed (the sound keeps its pitch), reverse (60 s at most), loop. Upload first with the quickstart; every option is on the operations page. 500 free credits a month, then $5 per thousand.