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Add audio is a Professional feature. Upgrade your plan to access it.
The Video Downloader Plus add audio tool lets you replace a video’s existing audio track or mix in a new one — background music, narration, or any audio file. All processing runs locally in your browser.

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How to add audio to a video

1

Open the tool

Go to vidow.io/tools/add-audio.
2

Upload your video

Click Upload video or drag a video file onto the page.
3

Upload your audio file

Click Upload audio and select the audio file you want to add.
4

Choose a mode

Select Replace to swap out the existing audio track, or Overlay to mix the new audio with the original.
5

Adjust timing

Set the offset for when the audio should start relative to the beginning of the video.
6

Export

Click Export. The output file is saved to your downloads folder.

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Supported formats

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Audio modes

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How it works

Audio processing runs locally in your browser using a WebAssembly build of FFmpeg. The tool muxes your audio file into the video container without re-encoding the video stream, keeping processing fast and preserving video quality. No data is uploaded to any server.

Merge Videos

Join multiple clips before adding audio.

Video Trimmer

Trim your video to the right length first.

Video Compressor

Reduce file size after adding the audio track.