iMovie ’09 is ideally suited for creating short movies, but Apple included a feature that appeals specifically to people who want to make music videos: beat markers.
Here’s how it works: whenever iMovie encounters a beat marker in your movie, it creates an automatic edit point. After setting several beat markers, you can quickly add video clips and photos which are cut to fit between each marker.
To begin, drag the song you want to use from the Music and Sound Effects browser to a new project in the Project Editor. At first, it will appear as a small green box, because no video is available.
Click the Action button on the song’s icon and choose Clip Trimmer; the Clip Trimmer interface appears over the top of the Event Browser, revealing the full song with its audio waveforms.
You have two options for adding beat markers. Drag the Beat Marker icon (a song note within the Clip Trimmer interface) to the clip, dropping it where you want to create an edit point. For less tedium and more fun, start playing the clip and press the M key anywhere you want a cut to appear.
Drag individual markers to fine-tune their position within the song, or drag them out of the song’s filmstrip to remove them. Click Done when you’re finished.
Drag your video and photos to the project. The clips conform to the edit points created by the markers. So, if you add a four-second clip to a two-second gap between beat markers, for example, iMovie trims the clip to two seconds. Even when you insert new clips between existing clips, the durations are adjusted to stay within the beat markers.
However, that slick auto-trimming does not apply when rearranging clips you’ve already placed within the movie. Those clips’ durations remain fixed once they’re added. If you move or edit them individually, the rest of the movie’s clips won’t adhere to the beat markers. The markers remain visible, though, so you can still cut to them manually.
If you do want to rearrange clips but don’t want to get out of sync, I recommend dragging new copies out of the Event Browser, dropping them onto existing clips, and choosing Replace from the pop-up menu that appears.
You can then fine-tune the portion of the clip that appears by “slipping” the clip, which changes the portion of the original clip that appears without affecting the clip’s length. Choose Clip Trimmer from a clip’s Action menu and, in the Clip Trimmer, click the top or bottom edge of the yellow selection box and drag it left or right.
If your clips contain sound you do not want in your composition, you'll have to adjust the volume for the video clips separately in the Events Browser before bringing them into the project. Select multiple video clips and choose Edit->Mute Clips to silence several at once.
If the Snap to Beats feature is enabled (under the View menu), you can reposition a beat marker in the Clip Trimmer, and the video that's cut to that marker will be recut to match the change. So, suppose you move a beat marker one second to the right: with Snap to Beats on, the video clip to the left of the marker becomes one second longer, and the clip to the right becomes one second shorter. With Snap to Beats turned off, moving the beat marker has no effect on the video clips.
In very little time, you’ll have a movie that’s edited to the beat—everybody get on your feet! Here's the final edited version of the movie I created for this example.
Jeff Carlson is the author of iMovie '09 & iDVD for Mac OS X: Visual QuickStart Guide (Peachpit Press; 2009) and the managing editor of TidBits.