Video

Replace Video Audio

Swap a video’s soundtrack for another audio file, without re-encoding the picture.

Video and audio
Video
Audio

Settings

Output

Result appears here after you select

{ } How to use

  1. Choose the video first, then the audio file — the order is what decides which is which.
  2. Pick what should happen when the two are different lengths.
  3. Select Process and download the result.

{ } How it works

Replace Video Audio works on the files you upload. Adjust the options, then select Process ▸ and it runs entirely in your browser — nothing is uploaded to a server — then shows the result in the Output panel.

Inputs

  • Video and audio — add the files to process (video/*,audio/*); they are read locally in your browser
  • When the lengths differ — choose one — Stop at the shorter one, Run to the longer one (default: Stop at the shorter one)
  • Bitrate — choose one — 128 kbps, 192 kbps, 320 kbps (default: 192 kbps)

Output

A downloadable MP4 file — use the Download button in the Output panel.

{ } Common uses

  • Put a music bed under a clip that was recorded with unusable sound.
  • Replace a noisy camera microphone track with a separate recording.
  • Dub a clip with a voiceover recorded afterwards.

{ } Limitations

  • The two are aligned from the start. There is no offset control, so audio that needs to begin part-way through has to be trimmed first.
  • The picture is copied rather than re-encoded, which keeps its quality — but it also means the video track has to be one MP4 can carry. Convert it first if it is not.

{ } FAQ

Is my data uploaded to a server?

No. Everything runs locally in your browser — your files never leave your device.

Can I process more than one file at once?

Yes — add several files and they’re all processed and downloaded together as a ZIP.

Is this tool free?

Yes — it’s completely free and needs no sign-up.

Does the picture lose quality?

No. Only the audio is encoded; the video stream is copied across byte for byte. That is also why it is fast compared with the tools that touch every frame.

What happens if the audio is longer than the video?

By default the result stops when the video does, which is almost always what is wanted — the alternative leaves the last frame frozen on screen while the music plays on. Switch to "run to the longer one" if that is deliberate.

Can I keep the original audio as well?

Not here — this replaces it. Mixing two tracks together is a different job with its own balance decisions.