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Replace audio in a video

Choose a video and its new audio, preview the timing, then create the result.

How it works

ImportChoose source
EditSet the change
PreviewReview result
ExportCreate file

InputMP4, WebM, MOV and M4V videoOutputMP4 or WebM video

MP4 · WebM · MOV · M4VChoose a videoDrop it here or click to choose a file.

When the original sound has to go entirely — a dubbed voiceover, a properly recorded audio track from a separate device, licensed music over unusable location sound — replacing is cleaner than mixing. This tool swaps the soundtrack for a new file, lets you align it against the picture, handles a length mismatch, and exports the result.

Aligning the new track

A soundtrack recorded on a separate device never starts at the same instant as the camera, which is exactly why film sets clap a slate. Find the equivalent moment in your material — a clap, a door, a hand on a table, a visible plosive — and align it in both. Once that single point matches, check a second point near the end of the clip: if the two recordings agree at the start and disagree later, you are looking at a sample rate mismatch causing drift, which alignment alone will not fix.

When the lengths do not match

New audio is almost never exactly as long as the video. Audio that runs longer can be trimmed at the head or tail, or faded out under the closing frames. Audio that runs short leaves silence at the end, which is usually fine for narration and awkward for music — fade the track rather than letting it stop dead. Resist the temptation to stretch audio to fit the picture: even small speed changes shift pitch and make speech sound subtly wrong, and viewers notice without knowing why.

Questions, answered

Is the original audio kept at all?

No. Replacing discards the existing soundtrack completely. Use the add-audio tool if you want the original to remain in the mix.

How do I line up separately recorded audio?

Align a sharp shared event — a clap, a door, a tap — visible in the picture and audible in the new track. Then verify a second point near the end to rule out drift.

What if the new audio is a different length?

Trim or fade a longer track under the closing frames; let a shorter one end early, with a fade if it is music. Avoid stretching audio to fit, since it shifts pitch.

Can I use this to dub a video into another language?

Yes, that is a standard use. Record or generate the new voice track, align it to the picture, and replace the original soundtrack.

Will the picture quality change?

The video is written as a new file, so it is re-encoded, but the framing, resolution and timing are unchanged. At a high quality setting the difference is not visible.

Replace audio in a video

Aligning the new track

When the lengths do not match

Questions, answered

Useful next steps