In iMovie, there are several ways to adjust the volume of video and audio clips.
Using the Audio inspector, you can increase or decrease the volume of entire audio or video clips in a project or of any video clip in an Event. You can also select several clips at once and change their volume at the same time. If the sound levels of the video clips in your project vary widely, you can also “normalize” their volume.
After clicking the Audio Waveform button in the Project browser or Event browser, you can modify the volume of audio and video clips in a project, or video clips in an Event, and you can also modify the volume of specific portions of clips. This gives you fine-tuned control over audio, letting you add nuance to the sound of your entire project.
Using the Audio inspector:
In the Project browser or Event browser, move the pointer over a video clip whose volume you want to adjust, and then choose Audio Adjustments from the Action pop-up menu (looks like a gear) that appears in the lower-left corner.
In the Project browser, you can also do this with an audio clip. Audio clips are represented by a purple or green bar below a video clip, as shown below. Background music is represented by a purple or green shaded area that appears behind your project clips.
You can select multiple video clips and then choose Audio Adjustments from the Action pop-up menu of just one of the clips to make volume adjustments to all of the clips at once.
In the inspector that opens, do any of the following:
To increase or decrease clip volume, drag the volume slider.
To mute clip volume, move the slider all the way to the left.
Later, to unmute clip volume, select the clip and then choose Clip > Unmute Clip.
The Clip menu appears in a light gray bar across the top of your computer screen.
To give the sound in the selected clip priority over other tracks, such as background music, select the checkbox next to Ducking, and then move the slider to set a volume percentage.
Selecting this checkbox causes the volume in other audio clips to decrease when the clip plays.
To restore all audio to its original levels, click “Revert to Original.”
If you make a change to an Event clip (source video), the change is reflected in any future project to which you add the altered video. This includes ducking. If you duck clip volume in an Event clip, the ducking effect applies in any future project you add that clip to.
You can remove any audio adjustments at any time by double-clicking the clip, clicking Audio in the inspector that opens, and then clicking “Revert to Original.”
In the Project browser or Event browser:
With your project open, click the Audio Waveform button at the bottom of the Project browser, or select an Event and then click the Audio Waveform button at the bottom of the Event browser.
In the Project browser and Event browser, blue waveforms represent the sound that was recorded with your video. In the Project browser, green or purple waveforms represent sounds and music you’ve added to your project. Names appear in the top-left corner of purple or green waveforms to make it easy to identify them.
Move your pointer over any volume bar (a thin black horizontal line) in a clip, and then drag up or down when the pointer changes to a resize pointer, as shown below.
This action changes the volume of the entire clip. To mute a clip, drag the bar all the way to the bottom of the clip.
To play back the selected clip at any time, move the playhead (the red vertical line) before the clip and then press the Space bar; press it again to stop playback.
To preview in an automatic loop as you’re making changes, choose View > Loop Selection. To stop the loop, press the Space bar.
The View menu appears in a light gray bar across the top of your computer screen.
There are several other ways to use audio waveforms to fine-tune the audio in your project. You can:
Modify the volume of just a selected portion of any audio or video clip.
Adjust the rate at which the audio in a clip fades in and fades out.
To learn other ways to use audio waveforms to fine-tune audio, go to this topic: Adjust the volume of a portion of an audio or a video clip.