Drop a file here or click to choose
Your file stays on your device. Processing happens locally in your browser.
What is Replace Audio in Video?
Replace Audio in Video removes a video's original sound and puts a new audio file in its place — a cleaner voice recording, a dubbed track or a different song. The original sound starts at 0% and the new audio at 100%; set where it starts and add fades. The picture is kept as it is. It uses the same in-browser engine as Add Audio to Video, so neither file is uploaded.
Replace the soundtrack of a video with a new audio file while keeping the picture untouched. Runs locally in your browser with WebAssembly.
Key features
- Original sound removed, new audio at 100% by default
- Audio start time and fade in / out
- Long audio cut at the end of the video; short audio stops or loops
- Picture copied without re-encoding when possible
- Runs in your browser — nothing is uploaded
Popular uses
- Replace a noisy camera recording with a clean microphone track
- Put a dubbed language track on a video
- Swap a copyrighted song for royalty-free music
Supported formats
Video: MP4, M4V, MOV, WebM, MKV, AVI. Audio: MP3, WAV, M4A, AAC, OGG, Opus, FLAC. Output keeps the video's format (AVI becomes MP4).
Troubleshooting
- The new audio is out of sync Change Audio starts at, or trim the beginning of the audio file first with Trim Audio.
Also known as: Change Audio of Video, Swap Video Soundtrack, Dub Video.
How it works
- Choose a video, then the new audio file. Both stay on your device.
- Replace mode is preselected (original 0%, new audio 100%). Adjust the start, volume and fades.
- Click Run and download the video with its new soundtrack.
FAQ
Replace or Add Audio — what's the difference?
Replace removes the original sound completely. Add Audio to Video mixes the new audio with it. Both pages use the same engine; you can switch modes on either.
Is my video uploaded?
No. Replace Audio runs entirely in your browser with WebAssembly. Your files never leave your device and are never sent to Fah Swe servers.
How do I keep the audio in sync with lips?
Use Audio starts at to shift the new track in steps of 0.1 seconds until it matches.
Can I keep a little of the original sound?
Yes — switch the mode to Mix and raise Original sound volume.