iMovie '11: Pin the start of a background music clip to a video frame
After you’ve added a background music clip to your project, you can move it so that it begins playing at whatever point in your video you’d like. This is called “pinning” the music clip to a video frame.
To pin background music to video:
In the Project browser, move the pointer along the upper-left edge of the background music well until it turns into a hand, and then drag the top-left corner of the background music well slowly to the right.
A pin icon appears in the corner of the background music well, and the background color changes from green to purple.
Continue dragging the pin until it’s positioned above the video frame where you want the music to begin playing.
The background music well turns to purple, indicating it’s been pinned to a video frame.
After you pin music to a video frame, unless you “unpin” it, the music stays with that frame even if you rearrange the order of your video clips.
To unpin background music:
If you’ve pinned background music to a video frame and now you want to rearrange the background music clips in your movie, you can unpin it.
In the Project browser, click to select the background music well (it becomes outlined in yellow), and then choose Clip > Unpin Music Track.
The Clip menu appears in a light gray bar across the top of your computer screen.