Free tools › Audio and video

Add audio to video

The picture from one file, the sound from another. The clip’s length wins.

This one runs on your credits. The picture from one file, the sound from another. The clip’s length wins.

Sign in and get 500 free credits every month — enough for many files — then drop the file in the workbench and run add audio to video 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 convert Add audio to video

Sign in — 500 free credits a month.
Drop the video and the audio file, in either order.
Choose replace or mix; run and download the MP4.

What happens to your file

Fylane tells the two files apart by what they are, not their order. The video is re-encoded as H.264 with the new sound as AAC; with "mix", the clip’s own sound and the new one are laid together at their own levels. The result is exactly the clip’s length: a longer soundtrack is cut at the end, a shorter one leaves silence — the report says which happened.

Questions

Can I start the music at a certain second?

Not yet — trim the audio first (Trim audio) so it begins where you want. An offset is a later feature.

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.add-audio",
    "options": {
      "mode": "replace",
      "file_ids": [
        "<second file id>"
      ]
    }
  }'

The same operation, video.add-audio — A soundtrack put on a video — the picture from one file, the sound from another; replace what it had, or mix over it. The video’s length wins. Upload first with the quickstart; every option is on the operations page. 500 free credits a month, then $5 per thousand.