How to use the Replace Audio in Video
- Choose the video.
- Choose the new audio file.
- Set the start time if the audio should begin later.
- Click Add audio and download.
Typical uses
- Put back audio that you cleaned up in an audio editor.
- Add a voice-over or a dubbed language.
- Replace noisy phone audio with a separate mic recording.
Syncing a separate recording
If the new audio is slightly early or late, set the start time, or use the Audio–Video Sync Fixer afterwards for millisecond-level adjustments.
Good to know
The video is copied without re-encoding. The new audio is converted to AAC, optionally delayed, looped and mixed with the original sound, and the result is exactly as long as the video.
Supported files
MP4, MOV, MKV, WEBM, AVI, WMV, FLV, M4V, 3GP, 3G2, MPEG, MPG, TS, MTS, M2TS, VOB, OGV, MXF, ASF, DIVX, F4V, SWF, DV, MOD, TOD, WTV, RM and RMVB video, with H.264, HEVC, VP8, VP9, MPEG-4, MPEG-2, WMV, Theora and other codecs. AV1 videos cannot be read in the browser yet. Files up to 1 GB each.
Frequently asked questions
What if the audio is longer than the video?
It is cut at the end of the video. If shorter, the rest is silent unless Loop is ticked.
Do I have to pay or sign up to use the Replace Audio in Video?
No. There is no account, no payment and no watermark. The only limit is 1 GB per file, set by what browsers can handle.
Are my files safe?
Yes. Files are converted locally in your browser and are never uploaded. When you close the page, nothing is left behind.
Can I use it on my phone?
Yes. Open the page in your phone's browser and choose a file. Phones have less memory than computers, so very large files are better converted on a laptop or desktop.