Add Audio to Video
Put background music or a voice-over on a video. The new audio replaces the original sound, and the result is trimmed to the shorter of the two.
Free · No sign-up · Files stay on your device
How to use Add Audio to Video
- 1Choose your video.
- 2Choose an audio file (MP3, WAV, M4A…).
- 3Click "Add audio" and download.
Features
- Replace a video's soundtrack
- MP3, WAV, M4A, OGG and more
- Video copied without re-encoding when possible
- MP4 output
- No upload
Length of the result
The finished video ends when either the video or the audio ends, whichever is shorter. Trim the audio first if you want it to start at a particular point.
Private, in-browser processing
This tool uses FFmpeg, the open-source engine behind most professional video software, running inside your browser. The first time you use it, the engine (about 30 MB) is downloaded once and then cached, so later conversions start straight away.
Frequently asked questions
Are my files uploaded?
No. Processing happens on your device with FFmpeg compiled to WebAssembly, so your video and audio never leave your computer or phone.
Why does it take a while?
Video processing is demanding, and your browser does it on your own device instead of a big server. Short clips take seconds; long or 4K videos can take several minutes. Keep the tab open until it finishes.
Can I keep the original sound and add music under it?
Not yet. The new audio replaces the original soundtrack.