Section 17.7. Editing Audio Clips | iLife 05: The Missing Manual

17.7. Editing Audio Clips

Fortunately, you can do more with your audio clips than just insert them into the Timeline Viewer. You can lengthen them or shorten them, make them fade in or out, shift them to play earlier or later in time, and even superimpose them. Best of alland here's one of the most useful features in iMovieyou can make their volume rise and fall over the length of the clip.

17.7.1. Making Whole-Clip Volume Adjustments

To make a particular clip louder or quieter relative to the other tracks, click its representation in the Timeline Viewer to select it. The clip darkens to show that it's highlighted.

Having selected an audio (or video) clip in this way, you can affect its overall volume level by using the "Clip:" volume pop-up menu shown in Figure 17-6. You can make it so quiet that it's absolutely silent, or you can actually make it 50 percent louder than the original.

Figure 17-6. If you set the volume pop-up all the way to 0, you mute the sound completelyfor this clip only. If you drag it all the way to the top, you actually boost the volume up to 150%a terrific way to compensate for weak camcorder microphones.
In any case, adjusting the pop-up menu makes the horizontal volume-level line temporarily appear on the selected clips.

Here are some pointers in this regard:

You can also type a percentage number into the "Clip:" text box. This isn't a feature only for the obsessively precise; it's a useful way to make sure that each of several audio clips are boosted to the same degree.
iMovie stores your Volume pop-up menu settings independently for every audio clip. That's why the Volume setting may seem to jump around as you click different audio clips.
If even 150 percent isn't enough of a volume boost, you can always open the audio clip in GarageBand for a quick boost. Drag the clip from the Finder into a waiting Real Instrument (blue) track, bump up the track's volume, export the result to iTunes, and then reimport the newly amplified file into iMovie.

17.7.2. Volume Adjustments Within a Clip

Being able to make the volume of a clip rise and fall along its length, as you can in iMovie, comes in handy in a multitude of ways:

It's a rare documentary or news show that doesn't begin a story with a full-volume, attention-getting shot (protesters shouting, band playing, airplane landing, and so on), whose audio fades to half volume after a few seconds, just in time for the reporter to begin speaking.
Similarly, you can "pull back" the musical soundtrack whenever somebody on camera is speaking, and then bring it back to full volume in between speeches. This technique is incredibly common in movies, TV shows, commercials, and just about every other form of professional video.
Suppose that the last second of a clip caught the unseemly off-camera belch of a relative at the dinner table. In a flash, you can edit it out, simply by silencing the audio just before the belch.
You can compensate for the volume drop that occurs whenever your interview subjects momentarily turn their heads away from the camera.
If you're a parent filming small children, your footage often winds up peppered with parental instructions recorded at a very high volume level, because you're right next to the microphone. ("Honey, stand over there by your brother," or "Watch out for the car!") These parental voice-overs often ruin a clipbut you can rescue them by adjusting the original audio from the camcorder, which you can edit just as easily as imported audio.
You can make create smooth fade-ins or fade-outs of your music (or the sound from the original video).

17.7.3. Volume "Rubber Bands"

The key to this feature is the new Show Clip Volume Levels command ( -Shift-L) in the View menu. (The same command appears in the shortcut menu when you Control-click an audio clip.) When you turn on Show Clip Volume Levels, a horizontal line appears on every audio and video clip, edge to edge. It's an audio-volume graph, which you can manipulate like a rubber band. Here's how it works (consider zooming in for greater control):

Click directly on the line and drag upward or downward (Figure 17-7, top). The original click produces a small spherical handle, and the drag produces a curve in the line from its original volume level. (Actually, you can simultaneously drag left or right to adjust the timing of this volume change.) Each "knot" in the line (the round handle) represents a new volume level that sticks until the end of the clip or the next volume level, whichever comes first.

After you create such a curve, the point where the audio deviated from its original volume is denoted by a tiny square handle (Figure 17-7, third from top). To make the volume increase or decrease more or less gradually, drag that tiny square handle left or right, closer to your round adjustment handle or farther from it.

Figure 17-7. Top: The horizontal line represents the audio clip's standard, 100% volume level. Suppose, in this case, that it's drowning out the spoken dialog in the video track above it. (That's a pretty common occurrence when you add, say, a pop song to your movie as a soundtrack.)
Second from top: As you drag the little "knot" vertically, you have two sources of feedback on how much you've increased or decreased the volume at that spot: the height of the line segment itself (in which the purple clip itself is the piece of graph paper, from 0% to 150%), and the number in the "Clip:" percentage box.
In any case, the orange handle tells you how much volume fluctuation you've introduced, but it doesn't let you specify how gradually you want the change to occur.
Third from top: For that purpose, drag the tiny square (indicated by the cursor) in any direction to control where the volume change beginsboth when, and at what level.
Bottom: Repeat the process in reverse when you want to bring the music back up after the dialog portion is over.

To make the volume take another dip or swoop, click elsewhere on the volume line and drag again. You've just created a second round orange handle, which you can position independently (Figure 17-7, bottom).
To remove a volume change, click the orange "knot" to select it, and then press the Delete key. (Or just drag it to the original volume level.) The knot disappears, and the "rubber band" line snaps back to the previous knot, stretched tight.
To make a volume change extremely sudden, click a knot to highlight it, and then drag the tiny square just to its left. You'll find that you can drag this little square until it's directly above or below the knotan instantaneous volume change.
Consider making your volume adjustments while the movie plays back. Each time you make an adjustment, the Playhead jumps to that spot. As you keep clicking and adjusting, clicking and adjusting, the Playhead keeps jumping back to that spot, saving you the trouble of having to rewind and play, rewind and play, as you fine-tune the fluctuation.
To restore the original, straight-line condition of a clip's volume, click each of the orange knots and press Delete until none of them remains.

Tip: When you're finished editing volume fluctuations, you can turn off the View

Show Clip Volume Levels command again. iMovie will remember all of the changes that youve made, and you'll still hear the volume changes on playback. But iMovie hides all of the handles and rubber-band graph lines, making it possible once again to drag clip edges to shorten them (which you can't do while volume graphs are visible).

17.7.4. Adjusting Many Clips at Once

You can adjust the volume levels of more than one clip simultaneouslya technique that comes in handy more often than you might think. For example, you may decide that all of the music excerpts you've grabbed from a CD are too loud compared to the camcorder audio. In one fell swoop, you can make them all softer.

You can select as many as you want, even if they're on different audio tracks. Start by selecting the clips you want to affect:

To select several non-consecutive clips, Shift-click them in any order: clip 1, clip 3, and so on. (Actually, -clicking works, too.)
To select several connecting clips, drag-select. That is, begin dragging in any empty part of a track. As you drag, iMovie selects any audio clip that even partly falls within the light gray rectangle you're creating.
To select all of the clips in both audio tracks, highlight one clip there. Then choose Edit Select All.
To unhighlight a selected clip, Shift-click or -click it.

Now when you adjust the "Clip:" volume pop-up menu, you're affecting all of the highlighted clips at once. (If you've fiddled around with the clips' rubber-band volume lines, adjusting the volume slider scales the volume of the whole thing up or down proportionally, maintaining the relative sizes of the fluctuations.)

Note: When several audio clips are highlighted, the volume pop-up menu reflects whichever clip has the highest volume level.

17.7.5. Locking Audio Clips to Video

Figure 17-8 illustrates a serious problem that results from trying to line up certain video moments (like Bill-Gates-getting-hit-with-a-pie footage) with particular audio moments (like a"Splat!" sound effect). In short, when you insert or delete some video footage after lining up audio clips with specific video moments, you shove everything out of alignment, sometimes without even realizing it. This syndrome can rear its ugly head in many video-editing programs.

Figure 17-8. Top: You've carefully lined up a barking sound effect with the beginning of the dog clip.
Second from top: Uh-oh. You've selected the clip right before the dog, in preparation for deleting it.
Third from top: Now you've done it. You've deleted the clip that was just to the left of the dog. The dog clip slides leftward to close the gapand leaves the barking sound behind, now hopelessly out of alignment with the video above it.
Bottom: If you had remembered to lock the barking clip to the video above it, as indicated by the tiny pushpins, the sound effect would have slid to the left along with the dog clip, remaining perfectly in sync.

You may wind up playing a frustrating game of find-the-frame, over and over again, all the way through the movie, as you try to redo all of your careful audio/video alignments.

In iMovie, the solution is especially elegant. Whenever you place an audio clip that you'd like to keep aligned with a video moment, get it into position and then lock it by choosing Advanced Lock Audio Clip at Playhead (or press -L). What happens next depends on how you've set things up:

If you've dragged or nudged the Playhead to the frame you care most about, iMovie locks the audio to the video at that frame, as indicated by the little pushpin (see Figure 17-8). Even if you later trim away some footage from the beginning part of the video clip, the sync moment remains intact.
If the Playhead isn't anywhere near the highlighted audio clip, iMovie simply locks the beginning of the highlighted audio clip to the video frame it's currently aligned with.
If you've highlighted several audio clips, once again, iMovie "pushpins" the beginning of each clip at its present video location.

Once you've locked an audio clip to its video, you no longer have to worry that it might lose sync with its video when you edit your video clips. Nothing you do to the video clips to its left in the Timeline Vieweradd, delete, insert, or trim themwill affect its synchronization.

It's important to understand, however, that locking an audio clip freezes its position only relative to the video clip above it. The audio clip isn't locked into a particular time in the movie (such as 5:23:12). Put another way, "Lock Audio" actually means " Don't Lock Audio (to one spot in the Movie Track); Let It Slide Around as Necessary."

Nor does locking an audio clip prevent you from shifting it. Dragging the audio clip will not drag the "attached" video clip along with it. You're still welcome to slide the audio clip left or right in its track, independent of any other clips. Doing so simply makes iMovie realign the clip with a new video frame, lining up the pushpin accordingly . (If you cut the audio clip and then paste it into a new location, it forgets both its original video-clip spouse and the fact that it was ever "married" to begin with. After pasting, it's pushpin-free.)

To unlock an audio clip, highlight it and then choose Advanced Unlock Audio Clip (or press -L again).

17.7.6. Cropping an Audio Clip

As you may remember from Chapter 14, the ability to crop , or chop the ends off a video clip, is one of the key tools in video editing. As it turns out, you can adjust the beginning or ending points of any audio clip even more conveniently.

Tip: If you use the Extract Audio command described on Section 17.9, you can even crop the original camcorder audio in this way, without cropping the video clip in the process. Doing so is a convenient way to trim out an audio glitch that appears at the beginning or end of a shot without having to crop the video clip.

You can shorten one of your music or narration clips from either the beginning or the end, just by dragging the corresponding end inward, as shown in Figure 17-9.

For finer adjustments, click one of the clip ends, so that the Playhead snaps to your cursor. Then press the right or left arrow key to move the handle in one-frame increments , orif you press Shift as you do soin 10 -frame increments. You might want to zoom in, using the Zoom slider at the left side of the window, if you're finding it hard to see the effects of your cropping maneuvers.

Note: As you drag the audio-clip crop handles inward or outward, any volume fluctuations you've added remain exactly where they werewhich means that they might just wind up in nowhere-land. You might drag the end point of a clip so far to the left that you'll never hear the fluctuations you had programmed for the very end of the clip. If your volume fluctuations seem to be missing, turn on View

Show Clip Volume Levels to make your volume graph reappear. Youll see the problem right away.

Figure 17-9. You can shorten an audio clip without actually deleting any of it, just by dragging the edges inward (shown here before and after). Does this sound familiar? It shouldyou can do the same thing with video clips.
At any time, you can restore the original length, or part of it, by dragging the edge outward again. (Note, though, that edge dragging doesn't work if Show Clip Volume Levels is turned on in the View menu.)

17.7.7. Splitting an Audio Clip

When you drag an audio clip's ends inward, you're not actually trimming the clip. You're simply shortening the audible portion of the full-length clip. At any time in your project's lifetime, if you decide that you've overshot, you can slide the clip ends back outward again.

However, you may have good reason to make the cropped-clip arrangement permanent. First, in complex audio tracks, your clips can become cluttered and difficult to "read," thanks to the duplicate clip ends. Second, dragging the ends of clips inward doesn't reduce the amount of disk space that your audio file uses, since iMovie hangs onto the full original in case you decide to uncrop it.

There is an alternative, however. You may remember reading about the power of the Edit Split Clip at Playhead command, which uses the current Playhead location as a razor blade that chops a video clip in two. In the Timeline Viewer, the equivalent command is called Split Selected Audio Clip at Playhead. As youd expect, it breaks the audio clip beneath the Playhead into two independent clips.

Tip: If your Edit menu doesn't list a command called Split Selected Audio Clip at Playhead, it's because your Playhead isn't in the middle part of a highlighted audio clip. If no audio clip is selected, or if the Playhead's vertical insertion point isn't running through it, the command says Split Video Clip instead (and has a very different effect).

Being able to split an audio clip is useful in a number of ways. For example, suppose that you've got a voice recording of a guy recounting his days at the beginning of Apple Computer. One line goes, "We lived in a rundown tenement on the Lower East Side of Cupertino, but nobody cared. We loved what we were doing."

Now suppose you've also got a couple of terrific still photos of the original Apple building, plus a photo of the original Apple team, grinning like fools in their grungy T-shirts and beards. After using the Split Audio Clip command, you can place the first part of the recording ("We lived in a rundown tenement on the Lower East Side of Cupertino") beneath the campus photos, and then delay the second utterance ("But nobody cared. We loved what we were doing") until you're ready to introduce the group photo.

Tip: You can't split a clip and then immediately move one of the halves . After the Split command, both clips remain in position, side by side, both highlighted. Whatever you do will affect both pieces, as though you'd never split them at all. Shift-click the piece you don't want before trying to drag or cut anything.

17.7.8. Moving an Audio Clip

You can drag audio clips around in their tracks just as you would video clips, or even back and forth between the two audio tracks.

In fact, because precision is often so important in positioning audio relative to the video, iMovie harbors a few useful shortcuts.

For example, whenever you drag an audio clip, the Playhead magnetically attaches itself to the beginning of the clip. As you drag, therefore, you get to watch the video in the Monitor window, corresponding to the precise moment where the sound begins.

GEM IN THE ROUGH
The Invisible Audio "Shelf"

When you're editing video, the Clips pane provides a handy temporary working space where you can set aside clips that you haven't yet placed into the movie. If you've ever worked with a page-layout program like InDesign, you're already familiar with this " pasteboard " effect.

Unfortunately, iMovie doesn't come with any pane or pasteboard where you can temporarily park audio clips.

If you think it might be handy to have such a workspace as you manipulate your audio clips, the solution is simple: Drag them, or paste them, far off to the right of the Timeline Viewer, beyond the right edge of your video. Then, just drag them back into place when you're ready for them. (Just don't leave any stray audio clips there by accident . You'll look pretty silly when your movie premieres at Cannes.)

Once the clip is highlighted, don't forget that you can press the left and right arrow keys to move it one frame at a time, or Shift-arrow keys to slide it 10 frames at a time. Even then, you'll see your exact position in the video by watching the Monitor window.

As a matter of fact, you can combine these two tricks. Once the Playhead is aligned with either end of a clip, you can press the arrow keys, or Shift-arrow, to move the Playhead and drag the audio clip along with it. You'll feel like the audio is somehow Velcroed to the Playhead.

17.7.9. Superimposing Audio Clips

iMovie may seem to offer only two parallel audio tracks, but that doesn't mean you can't have more layers of simultaneous sound. There may be only two horizontal strips on the screen, but there's nothing to stop you from putting audio clips on top of each other . By all means, drag a sound effect onto your already-recorded narration clip, or superimpose two or more different CD music recordings, if that's the cacophonous effect you want. When playing back your project, iMovie plays all of the sound simultaneously, mixing them automatically (Figure 17-10).

Figure 17-10. The first time you drag or paste a new audio clip onto an existing one, the situation is fairly clear, thanks to iMovie's tendency to put shorter clips on top of longer ones. It's impossible for a clip to become covered up entirely.

If you're having trouble sorting out several overlapping sound clips, consider selecting one and then choosing Edit Cut. Often, just getting one clip out of the way is enough for you to understand whats going on in its original location. Once you've got your bearings, you can choose Edit Undo to put it right back where it was.

Another tactic: When you click a clip, iMovie always selects the shortest one in the stack. If you have two overlapping audio clips, therefore, and you intend to select the longer one, click one of its visible ends.

Remember, too, to glance at the top of the Timeline Viewer as you click each audio clip. You'll see its name (if you've turned off the soundwaves, that is), which is another helpful clue when clips collide.

17.7.10. Scrubbing Audio Clips

Scrubbing once meant rotating reel-to-reel tapes back and forth manually, in an effort to find a precise spot in the audio (to make a clean splice, for example). In iMovie HD, you can scrub by Option-dragging your mouse back and forth across an audio clip. iMovie plays the sound under your cursor.

(This technique is extremely useful, but it works best when you're zoomed in and dragging very slowly. Note that Option is called Alt on some nonU.S. keyboards.)