Every piece of audio you add to your project can live in two places in the timeline: the foreground or the background. It might seem like a strange distinction at first (why not just have all the audio in the foreground?), but there’s a reason:

In summary, foreground audio is for sounds you need to position in a particular spot in your movie. Background audio is the kind you want to set and forget, allowing iMovie to manage when it starts and ends so you don’t have to.

All the audio you add to a project comes from the same location in iMovie: the Media screen, which you get to by tapping the Add Media button (on an iPad held on its side instead of upright, the media screen sits in the top-right corner). You used this same button when you added video clips to your project.

Tap Add Media and then choose Audio. iMovie shows you a list of sound types (Figure 21-2). Theme Music lists all the little, minute-long jingles Apple recorded to go along with your movie’s theme. Sound Effects offers dozens of cool and useful sounds that augment a movie, like footsteps or a ticking clock. (Foley artists create sound effects to round out a movie’s audio after the film has been shot. Quite a bit of the audio you hear in movies isn’t recorded by the camera; it’s recorded and added later, by foley artists.)

The remaining four choices—Playlists, Albums, Artists, and Songs—are just four ways to get at the music library on your device. Whether you buy your music straight from iTunes or sync it to your iDevice using iTunes on your computer, you can import any of your music into your movie (except copy-protected music you bought before 2009, when Apple still used copy protection on songs you bought; iMovie marks those songs as “unavailable.”)

Use the handy search box at the top of your Songs list to find a tune quickly.

Once you have the clip you want, tap it and two buttons appear (Figure 21-3). The first one, an arrow pointing down, adds the audio to your project. The second one, , previews it for you.

Figure 21-2. Tap Add Media followed by Audio to see all the sound clips you can use to enhance your movie. While Theme Music and Sound Effects offer unique audio clips, the remaining four choices (Playlists, Albums, Artists, and Songs) are just four ways to tap your device’s music library.

Figure 21-3. When you select a song, you see two buttons. The button previews the song so you know what you’re adding, while the down arrow button adds it. Also, notice the search field at the top of the list. You can use it to find the song you want quickly.

Adjust Timing

Once you add an audio clip to your project, you may want to change either its length or even its speed. In iMovie, you can do both.

Tip

Before you make any audio adjustments in iMovie on the iPad, tap the squiggly button shown in Figure 21-4 to display the clip’s waveform.

Figure 21-4. The iPad’s waveforms button (highlighted in blue) shows you patterns in your audio, making it easier to pinpoint important moments in a clip.

Trim Audio

To change the length of an audio clip, tap it once so the yellow border appears. Now you can drag either end to trim away the beginning or end of the audio. Once you let go, the clip is shorter.

Some useful advice for trimming audio:

• Spread two fingers outward in the timeline to zoom in on the clip (Split Clips) so you can fine-tune the trim.

• Keep the Undo button handy. Because iMovie on the iPhone doesn’t display a clip’s waveform (Adjust Timing), there’s a fair amount of guesswork required to trim a clip to the right spot. (The iPad version shows you the waveform when you tap the waveform button shown in Figure 21-4.)

• If you trim to the wrong place, never fear. You can use the same yellow handles to add audio back in. You can’t add more audio than was there originally, but you can add back anything you trimmed off.

Speed Changes

To speed up or slow down an audio clip, tap the clip and then choose Speed from the toolbar. iMovie shows you a speed slider (Figure 21-5). Drag it left to slow down the audio, and right to speed it up. When you change the speed of a clip, a little tortoise or hare icon appears next to it.

Figure 21-5. Top: Use the speed slider to make an audio clip faster or slower. (Notice the hare icon on the chosen clip—that means you sped it up. A tortoise icon means you slowed it down.) Bottom: Be sure to turn off the “Speed changes pitch” setting so the audio will keep its pitch when you change the clip’s speed.

Also, iMovie has a really cool ability to change the speed of a clip without changing its pitch. Normally, when you speed up audio, its pitch goes up, too, and when you slow it down, the pitch goes down. You can tell iMovie to preserve the pitch from the Project Settings menu—hit and then tap off the “Speed changes pitch” switch.

It probably won’t be long before we see an Oscar-nominated documentary that was shot and edited almost entirely on an iPhone. When that happens, the filmmaker may end up using iMovie’s built-in narration tool. Maybe that’ll be you.

What makes this tool so handy is that you can film a shot and then narrate it later with as many takes as you need to get it right. Each time you record a narration, iMovie adds it as a foreground audio clip, which you can always delete to try again.

To continue your documentary training, you need to learn how to do cutaways, where you switch from an interviewee’s headshot to a shot of what she’s describing, all while her voice keeps narrating.

To do a cutaway, you need to detach the audio from the video you recorded. Then you keep the audio track in place while you replace the video track.

iMovie offers two ways to detach audio from a video clip:

Figure 21-7. To add just the audio portion of a video clip to your timeline, tap the “Add audio” button.

The resulting audio stripe in your timeline is vibrant blue (see Figure 21-8). Trim the clip, move it, and adjust its speed or volume to your heart’s content.

Figure 21-8. iMovie marks these three kinds of foreground audio in different colors. The vibrant blue stripe (top) is detached audio, the lavender stripe (middle) is narrated audio, and the light-blue stripe (bottom) is a sound effect.

You might have a background song in your movie that’s so loud that there’s nothing background about it. Or there may be a moment when your annoying brother was yelling at your sister, and you’d rather not draw attention to it. In this and other cases, you need to adjust the audio volume levels.

Volume

To change the volume of a clip, select it and, if it’s a video clip, choose Audio from the toolbar. iMovie shows you a volume slider (Figure 21-9). Drag it to the left for a quieter clip and to the right for a louder one.

Tip

You can’t change the volume of just part of a clip, like you can on the Mac. In iMovie for iOS, you have to split the clip and then change the volume of the split part.

Unfortunately, there’s no ducking feature in iMovie for iOS (Ducking), so you need to be vigilant about adjusting the volume levels for different parts of your project.

Figure 21-9. iMovie’s audio toolbar houses a volume slider that makes the selected clip quieter or louder.

Just as breaking up a video clip can help with various editing tricks, so can splitting an audio clip. For example, you might want to pause a song for dramatic effect. When the song starts playing again, you want it to pick up where it left off. In a case like that, you want to split the clip.

Figure 21-10. When you use the Fade tool, yellow arrows mark the duration of the volume change. Drag them around to retime a fade.

Choose the audio clip and position the playhead where you want the split to occur. Choose Split from the toolbar and iMovie chops the clip in two. Now you can reposition the second part so that it picks up at the right moment in your movie.

If you need to repeat the same audio clip, don’t bother adding a second version of it to the timeline. Select the clip and choose Duplicate from the toolbar. iMovie creates a copy in the timeline.