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Drop the camera clip and the recording from your mic or recorder. They’re lined up by their sound, and the camera’s scratch audio is replaced with the clean track.
To sync audio recorded separately, drop the video and the recording together: the two soundtracks are compared, the recording slides into place, and Replace the camera sound puts the clean track under your picture. Press Export video and you have one file with good sound in sync.
This is the everyday version of dual-system sound: a camera or phone films, while a lavalier, a wireless mic kit, a handheld recorder or another phone in a pocket records the voice. The camera still needs its own microphone switched on, because its rough scratch sound is the reference the recording is matched against. Matching is precise to well under a millisecond when both heard the same words.
If there is no second recording and the one file is simply out of step, use fix the audio sync instead. For three or more devices, the multicam hub covers batch syncing and timeline export.
Select the video and the audio file together and drop them on Drop your video and its sound files, or press Choose files. WAV, MP3 and M4A recordings all open; on a phone, pick both from Files.
Look for Sure match next to the recording, then play a few words with Space. If it sounds doubled or echoey, press Try the next match, or nudge the recording with [ and ] (10 ms; Shift for 1 ms).
Replace the camera sound is already selected, with the recording under Use the sound from. Prefer some room tone? Choose Mix them and turn the camera down with its level slider.
Press Export video (Ctrl/Cmd+Enter) and download the result. The picture is copied as it is; a recording in a format the file can hold is copied too.
A second phone in a pocket with a clip-on mic is a surprisingly good recorder. Voice memo apps often save compressed M4A files, which open fine here. Turn off any setting that skips silences or enhances speech, since both change the timing of the recording and make it impossible to line up for the whole length.
| Choice | You hear | Good for |
|---|---|---|
| Replace the camera sound | Only the recording you pick under Use the sound from | Interviews, vlogs and talking heads |
| Mix them | Every file, each at its own level | Adding a little room tone or audience under a lav |
| Keep both | Each sound as its own track | Editing the mix later in another app |
| Keep the camera sound | The camera only | When you only want synced copies or a timeline |
When one recording simply replaces the camera’s, and the recording is in a format the video file can hold (AAC in an MP4, for example), its sound is copied without re-encoding. A mix, a fade or a drift correction means the sound is decoded and encoded once, at 192 kbps AAC for MP4 and MOV files.
A camera and a recorder keep time with separate clocks. Over a short clip that never matters; over forty minutes a difference of a few parts per million can open a gap of a frame or more. When the files overlap by at least 30 seconds, sync.video measures the offset at several points and, if the gap grows steadily, shows the drift next to the recording and stretches that sound in the export to stay in step from start to finish.
If a single video has sound that slips out on its own, with no second recording involved, the cause and the fix are different: see fix audio drift.
Drop the camera clip and the phone’s audio file together. As long as the camera’s microphone also picked up the voice, the two are matched by their sound automatically. Then keep Replace the camera sound and export.
No. Speech alone is usually enough. A clap at the start makes the match quicker to confirm and helps when the room is noisy.
Not automatically, because there is nothing to compare. You can drag the recording into place on the timeline by eye, using a moment you can see and hear, such as a clap.
Yes. Choose Mix them, then lower the camera’s level slider until it adds a little room tone without muddying the voice.
The picture never is: its compressed frames are copied. The sound is copied too when it can be, otherwise encoded once at a high bitrate.
Any device that saves a common sound file: WAV, MP3, M4A, AAC, FLAC or Ogg. That covers clip-on wireless kits, handheld recorders and phone voice memo apps. Unusual formats are converted on your device first.