Final Cut Pro HD | H•O•T Hands-On Training [Electronic resources] نسخه متنی

NOTE | Stereo vs. Dual-Mono Audio files

In Chapter 3, "Gather Your Media," you learned about the different audio capture settings. There are really only two that are important: stereo and dual-mono.

A stereo file has both channels linked for sync (their clip name is underlined) and with a little green bow tie between the clips. Channel 1 is panned all the way to the left, and Channel 2 is panned all the way to the right. Stereo is the correct file choice when you care about the spatial relationship of the sound, that is, whether it is on the left, right, or center.

You can easily convert between a stereo file and dual-mono by selecting the audio clip and choosing Modify > Stereo Pair, or pressing Option+L. There is no loss in quality by turning stereo linking on or off.

A dual-mono file has both channels linked for sync, but without the green bow tie. This means that both channels are panned to the center. Dual-mono is the default setting for audio capture and is used when the spatial relationship of the sound is not important, for example, in an interview.

1.

Open Hurricane, if it isn't already open. Then, double-click Seq B-roll added to load it into the Timeline.

2.

Play the sequence and watch the Audio Meter. Notice that the audio levels bounce between 6 and 12 dB, with a little yellow bar floating over the top of the green meters. The yellow bar is called the peak indicator. This shows you the level of your loudest sound over the last 3 seconds. The green bars indicate the sound level of your left and right audio channels.

The peak indicator is handy because it is often hard to see the levels of the green bars since they are bouncing so much.

By default, all odd-numbered channels are assigned to the left channel, and all even-numbered channels are assigned to the right channel.

As the audio gets louder, the green bars get taller. When the audio is too loud, even for an instant, the red clip lights light. It is critical that you adjust your audio levels so that the clip lights never light.

Generally, for dialogue, you want your meters to bounce between 6 and 12. They can go higher than this occasionally, but this is a good range for average levels. Running your audio at this level allows you plenty of headroom for loud sounds and sudden changes in volume. Set your volume (called "audio gain") much lower than this and it is hard to hear what is being said.

There are at least four ways to set audio levels for a clip, plus two more when you learn about the Audio Mixer. Which one is best? Whichever one helps you get your work done.

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3.

Double-click the Devanas clip to load it into the Viewer. Play the clip. Notice how the audio levels are low, between 12 and 18? These levels need to be increased so the speaker's audio is between 6 and 12.

4.

One way to change the level of a clip in the Viewer is to slide the audio level slider left and right until the audio level is where you want it. In this case, drag the Level slider to the right until the audio level is bouncing between 6 and 12.

5.

Another way to change the level in the Viewer is to click in the Level box to the right of the Level slider and type a number. In this case, increasing the level to 5 brings the volume up appropriately. Every clip is different; the key is to make decisions by watching the meters.

6.

A third way to change the level of a clip in the Viewer is to grab the red horizontal lines running through the middle of each waveform and drag them up (to increase the audio level) or down (to decrease the level). (These horizontal lines are also affectionately called rubber bands.)

Try this and see how, as you move these rubber bands, the Level slider moves, and the number inside the level box changes.

These are all great tips to know. However, I don't use any of them, because there is an easier way.

7.

Click the button at the bottom left of the Timeline that looks like a mountain range. This toggles on (or off) clip overlays. See the red rubber bands in the audio clips? You can easily set audio levels of clips directly in the Timeline by adjusting these bands. (These lines get their name, rubber bands, for their flexibility, which you'll understand better as you start to set keyframes a little later in this chapter.)

These volume rubber bands exist in both the Timeline and the Viewer. They work the same way. You can use whichever is the easiest for your method of working.

8.

Play each of the clips in the Timeline and set the levels so that the meters are bouncing between 6 and 12. When you play the sequence now, all the voices should sound about the same, in terms of volume.

What do you mean, you can't hear the voices because the B-roll audio is too loud? Oh, yeah. You should probably fix that.

9.

On the extreme left side of the Timeline are green visibility indicators. When these lights are lit, you can see the contents of a video track, or hear the contents of an audio track. Turn the visibility indicator off for audio tracks a3 and a4, and you'll be able to hear the voices a lot better.

10.

Turn the visibility indicators on for A3 and A4 and off for A1 and A2, because you now need to adjust the audio levels of the B-roll. Better yet, turn on all visibility indicators and turn on the Solo buttons for A3 and A4.

The Solo button automatically mutes A1 and A2 and allows A3 and A4 to play.

11.

Go to the last B-roll clip, B storm flood, and play it. First, bring the audio level up a bit so you can hear it better.

Hmmm…the truck is going from the left to the right, but the audio stays center. Panning the audio from left to right as the truck moves would improve this effect.

12.

Double-click the clip to load it into the Viewer. Click the audio tab (Mono a1) to display the waveform. In case you raised the audio all the way up, as I did, bring the audio level down to, say, 2. (Note, this is a positive 2, not a negative 2.)

Now, this truck clip, unlike the other clips, has only one audio track: a mono track which is panned to the center. And the audio waveform is so small as to be almost invisible. Sigh. Not all audio is great quality.

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13.

Drag the Pan slider up and down and watch the dark-purple line in the center of the waveform window move. This purple line indicates the pan of this clip from left to right.

Simply dragging the pan to a new position doesn't give you the effect you want, because dragging the line moves the sound to the left, or right, and parks it there. You want it to change over time. Change requires keyframes.

14.

Drag the Pan slider until you can see the purple line clearly, somewhere in the middle of the window. Select the Arrow tool and hold down the Option key so that it turns into the Pen tool (or just select the Pen tool) and click near the end of the line to set a keyframe. Drag this keyframe up near the top of the waveform window.

To repeat, you create keyframes by Option+clicking with the Arrow tool or clicking with the Pen tool.

Final Cut, unlike virtually every audio program I've ever used, puts the left pan on the bottom and the right pan on the top.

15.

Next, drag the Pan slider down to 1 (the default setting) and watch the angle of the line change.

What you've done is set two keyframesone at the beginning of the clip, using the Pan slider, that puts the sound on the extreme left, and one at the end of the clip, using the Pen tool, that puts the sound on the extreme right.

Because the two locations are different, the sound moves from side to side during the playing of the clip.

16.

Increase the volume level of the clip to 12 (all the way up) and play the clip. (The technical term for volume level is "gain.")

Hear how the truck now sounds like it's moving from left to right? Final Cut automatically calculated all the intermediate steps so that the sound moves smoothly from one side of the screen to the other. This technique is used all the time to have sound effects reinforce movement on the screen.

Every audio clip, both mono and stereo, has pan controls. Feel free to experiment with other clips.

17.

You'll be working a lot with keyframes for the rest of this book. However, for now, take a break. Save your work. Next you'll be working with music and effects.