PRIVATE BROWSER PROCESSING
Add a new audio track to video without opening a full editor
Use a music bed, voiceover, corrected recording or replacement soundtrack. Choose video and audio separately, then replace the original sound or mix both tracks.
Add audio to video
Replacing a track should not require a twenty-button timeline
Mix mode expects the source video to have audio. If it does not, the tool falls back to using the new audio as the replacement. Added audio is padded or trimmed to the video duration.
Privacy and limitations
Processing uses FFmpeg WebAssembly locally. The video is not uploaded by this tool. Closing or refreshing the page clears the working file. Speed depends on the browser, device memory, source codec, duration, and resolution, and tools that re-encode are not lossless.
Common questions
Which video formats are supported?
The FFmpeg core handles common formats such as MP4, MOV, WebM, MKV, AVI, MPEG, M4V, 3GP, TS and WMV, though the browser may not preview every format.
Is my video uploaded to DJAI?
No. The source file is read and processed in your browser on your device.
Why can the first run take longer?
The browser downloads an FFmpeg WebAssembly core of roughly 31 MB the first time processing is needed; caching can help later runs.
BUILD WITH DJAI
Want to build a tool like this one?
This tool runs entirely in the browser. Explore DJAI Academy’s practical building courses.