Creative Commons License

Editing and Mixing Audio

While not a full-featured audio editing system, Final Cut has a good set of basic tools which allow you to perform most common audio processing functions. There's several ways to work with audio in FCP:

1. Editing individual audio clips in the Viewer window

When you double-click an audio clip in your browser window it opens up in the Viewer just like a video clip - except instead of seeing the video image you see the audio waveform (1). In the viewer window you can set in and out points just like you would with a video clip. You also have sliders at the top of the window (2) which allow you to set the overall level or pan of the clip. When you have the clip set the way you want it you can drag it to the timeline by clicking on the small icon in the upper right hand corner which has a hand on a speaker (3).

In addition to setting the overall level of the clip, you can vary the clip's level or pan settings over time by setting audio keyframes. There are three ways to do this in the viewer window. The first is to use the level/pan sliders and the keyframe buttons next to them to change the level. Set the level or pan setting to what you want to start at and click the keyframe button (4) next to it. This sets a keyframe which records that setting at that time. Now go to a later time in the clip and drag the slider to a different level - a new keyframe will be created automatically at the current time and the audio level will change over time between the two keyframes when you play it back.

When you set level or pan using this method you can see them visually represented by thin lines superimposed over the waveform in the Viewer window (5). The red line represents the audio level while the purple line represents the pan setting. Keyframes appear as small dots on these lines. You can add keyframes to the line right in the window using the pen tool (available in the tool palette) or by holding down the Option key as you hover your cursor over one of the lines (the cursor will turn into the pen tool temporarily when you do this). You can also change the keyframes themselves simply by dragging the dots up or down in the window.

2. Mixing audio levels on the timeline

Once the clip is on the timeline you can change it's levels using the red line/keyframes in much the same way you do in the Viewer window. In the lower left hand corner of the timeline are a few buttons - the third one in from the left shows a line with a couple little dots on it. This is the level overlay button, and when you click it you will see the red lines appear on all audio clips on the timeline. You can change these just as you do in the Viewer window using the pen tool(or holding the option key to temporarily switch to the pen tool). If you want to see the waveforms on the audio tracks as well, you need to change the sequence settings. On the menu bar choose Sequence>Settings... or use the keyboard shortcut Apple-0 to open the settings window. This window allows you to change a lot of aspects of your sequence, but for now we're jsut concerned with the timeline settings. Click on the Timeline Options tab at the top of the window, and from the options which appear click the checkbox next to "show audio waveforms". Click the "OK" button at the bottom of the window and you should see the audio waveforms superimposed on the audio clips themselves.

When working with audio on the timeline it can be useful to have the tracks themselves taller so you can see the waveform more clearly and have greater control over the audio levels. Just to the right of the button we clicked to turn on audio overlays is another button which has what looks like a small bar graph on it. This lets you change the height of the tracks on the timeline, and each of the four bars represents a different track height. Just click on one of the larger bars to increase the size of the tracks as necessary.

You can trim audio clips on the timeline using any of the editing tools described in the timeline editing notes - Roll, Ripple, Slip, Slide and Razor Blade.

3. Audio Transitions

We haven't covered video transitions yet, but starting with audio transitions is nice because there's a lot less to worry about. The basic transition is a cross-fade, which fades one audio clip out as the next one fades in, creating a smooth transition between the two.

Transitions are usually placed between two clips where they meet on the timeline, so you start by selecting a cut between two clips (it will highlight with a thin grey bar which overlaps the ends of the two clips). From the menu bar choose Effects>Audio Transitions>Cross Fade(0db) and a light grey bar will appear on the timeline between the two clips representing the duration of the crossfade. if you play through it now you will hear the first clip fade smoothly into the second. If the crossfade occurs too quickly or slowly you can adjust it's duration by dragging the edge of the crossfade in or out to make it shorter or longer.

Crossfades use some excess media from the two clips affected - taking audio after the out point of the outgoing clip and before the in point of the incoming clip. This means there needs to be audio there for the crossfade to work with. If either of your clips starts or ends at the absolute beginning or ending of the original media the crossfade will not work (it may appear very short when you apply it - this is because there's not enough media to work with). As long as the in and out point of each clip is at least a second or more away from the beginning or ending of the original media you should be fine.

To remove a crossfade, just select it and hit the Delete key.

There are only two audio transitions - Crossfade(0db) and Crossfade(+3db). The difference is in how they sound. The 0db one does a linear fade across the two clips - this can result in the overall sound level dipping slightly right in the middle of the transition. The +3db fades the clips in more of a curve which is a little louder in the middle to compensate for the perceived dip. I use the +3db most of the time but it's really up to your ears to tell you which one is right for your particular project.

+3db is the default audio transition and can be applied by selecting the cut on the timeline and hitting Apple-Option-T. This allows you to quickly add transitions without having to use the menu every time.

That's the basics of mixing and editing audio in Final Cut. We'll cover audio filters later in part 2 of the class, but most of the time you'll be working with the tools described here.