How to sync audio and video in iMovie

Before you start

Use the video and a separate sound recording of the same take. Keep the camera's original sound until you have checked the match: it can help you find the same sound in both recordings. If you filmed a clapperboard, match the first frame where the sticks close (or the first white frame of a flash) with the start of the clap's spike. See how to sync sound with a clapperboard.

Sync footage recorded without a clapperboard

Look for a sharp sound present in both recordings: a hand clap, a door closing or a tap on a table. If the camera recorded sound, compare that moment in its waveform with the separate recording and drag the audio to match. A visible impact can also give you a frame to line up with the sound. Without a shared sound or visible cue, you will need to judge the match by playback, such as a close-up of someone speaking.

Sync in iMovie on iPhone

1. Choose a sync point

   Open your movie project and find a clear clap or another shared sound in the take. For a filmed clapperboard, put the playhead on the frame where the sticks close. If you did not record a clap, use the shared sound you identified before starting.

2. Add the sound file

   Tap Add Media (+), then Files, and choose your recording.

3. Make it movable

   If the clip went in as background music (green, at the start of the project), tap it, tap Actions, then Foreground. Now you can move it freely.

4. Zoom in

   Pinch open on the timeline until the frames around your sync point are easy to see.

5. Drag it into place

   Touch and hold the sound clip until it lifts, then drag it so your chosen sound matches the same moment in the video. For a clap, place the start of its spike under the clap frame.

6. Check the match, then mute

   Play the take and check that the separate recording matches the picture. Keep the camera audio available while comparing. Once the sync is right, tap the video clip, open its audio controls and tap Mute.

Sync in iMovie on Mac

1. Show the waveforms

   Drag the video into the timeline, click Settings at the top right of the timeline and tick Show Waveforms.

2. Attach the sound under the clip

   Drag your sound file from the Finder and drop it just under the video clip, so a small bar connects them. Don't drop it in the background music area: sound there doesn't move with the video.

3. Find your sync point

   Zoom in with Command-plus or a trackpad pinch. Step through the video with the Left and Right arrow keys to the clap or other shared cue. If you filmed a clapperboard, use the first closed-sticks frame.

4. Drag the sound into place

   Drag the attached sound clip until your chosen sound lines up with the same moment in the video. With camera audio, compare the matching spikes in both waveforms.

5. Check the match, then mute

   Check playback before removing the camera sound from the mix. Once the separate recording matches the picture, select the video clip and press Shift-Command-M to mute it. Leave the original audio in place in case you need to compare again.

Check the beginning and end of the take

Play a short section with a visible action or someone speaking. Once the separate recording matches the picture, mute the camera's original sound so you do not hear both tracks. Check again near the end of a long take. If the beginning matches but the end does not, moving the entire audio clip will not fix both points; the recordings may be drifting apart. Keep the originals and investigate their timing before cutting the scene.

What iMovie can't do

• No automatic sync on iPhone, iPad or Mac. Every take is lined up by dragging.
• No way to nudge a sound clip one frame at a time, so zoom in as far as you can before the final drag.
• Check each take on a close-up of someone talking. Two or three frames off is easy to see on lips.

For a whole day of takes, an editor with automatic sync, like DaVinci Resolve (free) or Final Cut Pro, will save time. See how to sync audio in DaVinci Resolve.

For the iMovie controls used here, see Apple's guides to editing audio on iPhone and audio waveforms and volume on Mac. The sync checks above describe how to use those controls with your recordings.

Questions