FCP X: Audio in Compound Clips

Posted on by Larry

logo-FCPX[This article grew from a series of emails from a reader who was confused about how compound clips work.]

One of the benefits to using compound clips in Final Cut Pro X is improved audio handling. For example, the interview guest audio is soft, while sound effects and music are loud.

Since there is no audio mixer or track support in Final Cut, we need to do this another way – compound clips.


A Compound Clip is a container for one or more clips which is stored in the Browser and can be applied to one or more project files.

NOTE: Compound clips are similar to Nests in Final Cut Pro 7 or Adobe Premiere Pro CC.

Compound clips are, essentially, projects – or sub-projects, if that helps you wrap your brain around them. A compound clip does not need to match the settings of the project into which it is inserted; though most of the time it does.

Here’s an example of where a compound clip can be useful. This is a short promo for a documentary on Mars. Dr. Cerf’s audio is about 20 dB too faint, while the sound effects and music are plenty loud.

I have several options to increase the level of Dr. Cerf’s audio:

The first option is, generally, the best one to try initially, because it is simple to understand and easy to do. However, Dr. Cerf’s audio averages -20 dB, and there’s only 12 dB of gain that we can add by increasing the black volume line in each clip. This first option is good, but insufficient.

The second option, adding an audio filter to each clip, is also a good idea, but impractical. The problem is: what happens if I need to make changes to my original settings? Now I’ve got to go through each clip and tweak. This isn’t hard for a 30-second promo, but it would very quickly become unworkable for an hour-long documentary.

NOTE: By the way, the reason I don’t like the Gain filter is that it increases the level of an audio clip, but does not include any distortion protection. The Limiter or Multi-band Compressor are much better – and safer – options.


When we have a lot of audio clips to which we want to apply the same effect, a compound clip is the best of both words: it provides a single point of adjustment, with the ability to add or modify variation between clips.

The easiest way to create a compound clip is to select all the clips you want to put inside it, then select File > New > Compound Clip.

NOTE: If you are creating a compound clip from scratch, as opposed to creating it from existing clips as we will do here, it is essential that the audio output settings of the compound clip match the audio settings for your project. Otherwise, you’ll get strange results, as this article explains.

Give the new clip a name and decide in which Event you want to store it in.

NOTE: Most of the time, I store compound clips into my Projects event. However, for bigger projects, I’ll create a separate event specifically for compound clips.

All selected clips are now bundled into a compound clip in the Timeline, which is also displayed in the Browser. (You can see the new compound clip highlighted in yellow, above.)


Open the Effects Browser and select Levels from the Audio Category on the left. Scroll down to the Logic section, then drag the Limiter filter on top of your compound clip.

NOTE: These effects used to be called “filters.” I use “effects” and “filters” interchangeably.

The filter you just added applies its settings to everything contained by the compound clip. We haven’t adjusted the clips, we’ve adjusted the container that holds the clips.

NOTE: There are two different Limiter filters in Final Cut. Both work the same. The version in the Logic section supports creating presets internally, while the version at the top of the Levels section requires you to create presets using the Save Effects Preset menu.

To adjust an audio filter, select the compound clip (or any clip containing the audio filter), go to Inspector > Audio tab, and click the small icon next to the filter you want to adjust. This opens the audio filter interface.

NOTE: Each audio filter interface looks different. This is what the Limiter filter  looks like.

Adjust the filter as you see fit.

NOTE: Here’s an article that shows how to adjust the Limiter filter.

Adjust the Limiter to get the levels you need, without over-amplifying your audio. As the Limiter article makes clear, the only setting that changes from project to project is the Gain setting on the far left of the filter.


The benefit to a compound clip is that you can easily double-click the clip in the Timeline to “open” it up to make individual adjustments to each clip. These could include:

NOTE: The hash marks at the front and back of the clip indicate that this is a compound clip with a fixed duration, unlike a normal project.

To return to the project timeline, click the small, left-pointing arrow at the top left of the Timeline itself.


Compound clips allow you to quickly apply effects to collections of clips, without having to apply the effect to each clip individually.

I don’t use these all the time, but when you need to apply the same effect to multiple clips at once, a compound clip is a very fast way to get it done.

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