Adjusting Clip Audio Levels and Pan Using Keyframes

Instead of setting the audio level or pan of an entire clip to the same level throughout a clip, you can mix your levels and stereo placement dynamically, raising and lowering the audio level or changing the stereo pan of a clip numerous times within the same clip. To do this, you use keyframes.

Keyframes can be used throughout Final Cut Pro with any feature whose parameters can be changed over time. Keyframes allow you to specify different audio level or pan settings in an audio clip at different points in time. The audio level overlay in your clip automatically adjusts from one keyframed level to another using a smooth curve.

You can also record audio level and pan automation using the Audio Mixer, which creates keyframes. These keyframes can be adjusted by hand, directly in the Viewer or the Timeline.

Note: Unlike the visual keyframes that you can set for motion settings, the shape of audio level and pan level curves can’t be altered.

Tools for Adjusting Keyframes

When you adjust audio levels and pan settings in the Timeline and Viewer, you mainly use the Selection and Pen tools. The Pen tools allow you to add, move, and delete audio level and pan keyframes in the clip overlays in the Timeline as well as in the Viewer.

Figure. Pen tool and Delete Point tool in the Tool palette.
  • Pen tool: The Pen tool allows you to add keyframes to the audio level overlay (press the P key to select the Pen tool).
  • Delete Point tool: The Delete Point tool allows you to remove keyframes from the audio level overlay (press the P key twice or hold down the Option key while you are using the Pen tool to select the Delete Point tool).

Using the Option Key to Temporarily Enable Pen Tools

When using the Selection tool, holding down the Option key and moving the pointer over the audio level overlay in the Timeline makes the Pen tool the active tool. This is a fast and easy way to create keyframes to adjust your levels.

Holding down the Option key and moving the pointer to an existing keyframe temporarily enables the Delete Point tool, so that you can quickly delete keyframes you don’t want.

Using the Command Key to Gear Down Adjustment Speed

In Final Cut Pro, items you drag onscreen normally move at the same speed at which you move your mouse across your work surface. When you’re dragging the audio level overlay, this usually works just fine. However, you can drag even more precisely by holding down the Command key after you start dragging an item.

If you hold down the Command key while dragging the audio level overlay, the overlay moves much more slowly, and its numeric value changes in much smaller increments. This is especially valuable when mixing levels in the Timeline, where the small height of clips can make precise level adjustment difficult.

Note: The Command key works with nearly any dragging operation in Final Cut Pro.

Keyframe Controls in the Viewer

The keyframe controls are located next to the slider controls in the Viewer.

Figure. Level Keyframe button and Pan Keyframe button in the Audio tab of the Viewer.
Figure. Keyframe button and keyframe navigation buttons.
  • Level Keyframe button: The keyframe button to the right of the Level field places a keyframe on the audio level overlay at the current playhead location. You place keyframes on the audio level overlay in preparation for creating a dynamic change in the level when you’re mixing.
  • Level keyframe navigation buttons: These buttons, to the left and right of the Level Keyframe button, allow you to move the playhead forward or backward from one keyframe on the audio level overlay to the next.
  • Pan Keyframe button: This button, to the right of the Pan slider, places a pan keyframe at the current playhead location on the pan overlay. These keyframe markers can be used in preparation for dynamically panning an audio clip’s output from one stereo channel to another.
  • Pan keyframe navigation buttons: These buttons, to the left and right of the Pan Keyframe button, allow you to move the playhead forward or backward from one keyframe on the pan overlay to the next.
  • Reset button: This button deletes all marked keyframes on both the audio level overlay and the pan overlay of the currently selected audio track and resets both to their original values (0 dB for the audio level and –1 for the pan level).

Working with Keyframes

Until you create at least one audio level or pan keyframe in your audio clip, changes you make affect the level or stereo placement of your entire clip. Although you need two keyframes to do anything useful, once you set the first audio level or pan keyframe, any changes you make to the keyframed levels anywhere else in the clip generate additional keyframes.

To set a keyframe
Do one of the following:
  • Move the playhead in the Viewer to the place where you want to set a keyframe, then click the Level Keyframe or Pan Keyframe button.

    Figure. Audio tab showing a keyframe on the pan overlay.
  • Select the Selection tool (or press A), then hold down the Option key and position the pointer over the level overlay. The pointer turns into the Pen tool. Click a level overlay with the Pen tool to add a keyframe at that point.

    Figure. Audio tab showing the Pen tool over the pan overlay.

    The keyframe appears as a small diamond on the overlay.

To set additional keyframes
  1. Move the playhead to another point in the clip where you want to set a keyframe.

  2. Do one of the following:

    • Drag the Level or Pan slider to set a new keyframe at that level or value.

    • Type a number in the appropriate field to set a new keyframe at that level or value.

    • Click a keyframe button to add a keyframe to the audio level or pan overlay at the overlay’s current level.

    • Hold down the Option key and click an overlay with the Pen tool to add a keyframe at that point without changing the level of the overlay. You can add as many keyframes as you want by clicking repeatedly with the Option key held down.

The keyframe appears as a small diamond on the overlay you added it to.

To move the Viewer playhead from one keyframe to another
Do one of the following:
  • Click the left or right Level or Pan keyframe navigation button to move the playhead to the next keyframe to the left or right of the playhead.

  • Press Option-K to move the playhead to the next keyframe to the left of the playhead.

  • Press Shift-K to move the playhead to the next keyframe to the right of the playhead.

To adjust the level or pan value of a single keyframe
Do one of the following:
  • Move the playhead to the keyframe you want to adjust, then drag the appropriate slider to a new value.

  • Move the playhead to the keyframe you want to adjust, type a new value in the appropriate field, and press the Return key.

  • Move the pointer over the keyframe you want to modify. When the pointer becomes a crosshair pointer, drag the keyframe you want to modify.

    • Dragging an audio level keyframe up raises the audio level; dragging down lowers it. As you drag, a box shows you the current level of the keyframe.

    • Dragging a pan keyframe up moves the audio toward the left stereo output channel; dragging down moves it to the right stereo output channel. As you drag, a box shows you the pan setting of the keyframe.

    • Dragging a pan keyframe for a stereo pair vertically in the waveform display area transposes the left and right channels of a stereo pair.

To adjust a section of an overlay in the middle of four keyframes
  • Move the pointer over the section you want to adjust. When the pointer turns into the Adjust Line Segment pointer, drag the section up or down to modify it. The rest of the overlay before and after the four keyframes remains untouched.

    Figure. Audio tab showing a section of the audio level overlay being dragged with the Adjust Line Segment pointer.
To move a keyframe forward or backward in time
  • Place the pointer over the keyframe you want to modify. When the pointer becomes a crosshair pointer, drag the keyframe forward or backward along the overlay.

    Figure. Audio tab showing the crosshair pointer over a keyframe on the audio level overlay.

    As you drag, a box displays the timecode duration of the change you’re making.

    Figure. Audio tab showing a keyframe being dragged and box displaying the timecode duration of the change.
To delete a keyframe
Do one of the following:
  • Control-click the keyframe you want to delete, then choose Clear from the shortcut menu.

    Figure. Shortcut menu showing the Clear command.
  • Move the playhead to the position of the keyframe you want to delete, then click the Level Keyframe or Pan Keyframe button to delete the keyframe.

  • Place the pointer over the keyframe you want to delete. When it becomes a crosshair pointer, drag the keyframe up or down out of the waveform display area. When the pointer turns into a small trash can, release the mouse button.

    Figure. Trash can pointer.
  • Hold down the Option key and position the pointer over an existing keyframe. The pointer turns into the Delete Point tool. Click an existing keyframe with the Delete Point tool to delete that keyframe.

    Figure. Audio tab showing the Delete Point tool positioned over a keyframe on the audio level overlay.
To delete all keyframes
  • Click the Reset button.

    Figure. Reset button in the Audio tab of the Viewer.

    All keyframes (both audio level and pan) are deleted, and the audio level of your clip is reset to 0 dB.

Using Keyframes to Adjust Audio Levels

You need at least two keyframes to make any dynamic change from one audio level to another in a clip.

Figure. Audio tab showing a waveform and an audio level overlay with two keyframes.

In the example above, the section of the clip to the left of the keyframes has a level of –30 dB, and the rest of the clip to the right of the keyframes has a level of 0 dB. This is the simplest type of level change you can make.

A more sophisticated change in levels—for example, introducing a slight boost in the level of a few notes in a music track—requires three keyframes.

Figure. Audio tab showing three audio level keyframes, with the middle keyframe being dragged to change the audio level.

In the example above, the audio level of the clip starts at –3 dB and then rises along a curve, peaking at +6 dB on the note that’s playing at that point. The audio level then lowers along another curve, ending back at –3 dB.

Three keyframes allow you to boost or attenuate (lower) a section of audio along a curve, but to make less gradual changes to longer sections of audio, you’ll need to use four.

Figure. Audio tab showing four audio level keyframes.

In the example above, the audio level, instead of rising or lowering constantly, changes from –3 dB to -26 dB during the first two keyframes and then remains constant. The final two keyframes boost the level back to –3 dB, where it remains for the duration of the clip.

Example: Using Keyframes in the Timeline to Automate Audio Levels

Suppose you’ve edited a music clip and a clip with voiceover narration together in your sequence.

Figure. Timeline window showing a music clip and a voiceover narration clip in the audio tracks.

There are long pauses between the narrator’s lines, during which you want the music to be the dominant audio track. So you set the overall level of your music to -4 dB, because that’s the level at which the audio sounds best between the narrator’s lines. When the narrator speaks, however, you want the level of the music to drop so it doesn’t compete with the narrator for attention.

If you hold down the Option key (while the Selection tool is selected) and click the audio level overlay of the music clip with the Pen tool, you can place groups of four keyframes at each place where a line is spoken by the narrator.

Figure. Timeline window showing four keyframes set on the audio level overlay of an audio clip.

Then, releasing the Option key, you can drag the area in the middle of each group of four keyframes down, to lower the level of the music while the narrator speaks.

Figure. Timeline window showing sections of the audio level overlays in audio tracks being adjusted between keyframes.

Finally, you’ll want to move the outside pair of each group of four keyframes outward a bit, so the volume of the music doesn’t change too abruptly and startle the audience. Less-steep slopes between keyframes result in more gradual fades from one audio level to the next.

Figure. Timeline window showing a keyframe being moved to adjust the slope of the audio level overlay between two keyframes.

Example: Setting Subframe Audio Keyframes to Eliminate Clicks

Sometimes, when you find the perfect edit point for cutting a clip into your sequence, you’ll notice a pop or click in the audio. This happens when you make a cut on an awkward sample that just happens to occur at a frame boundary.

You can eliminate pops and clicks by setting keyframes for your audio levels to within 1/100 of a frame. Usually, changing an audio edit point by just a few hundredths of a frame eliminates the clicking.

To set and adjust subframe audio level keyframes
  1. Open the clip in the Viewer and click the Audio tab.

  2. Move the playhead to the edit point that’s causing the click by pressing Shift-I or Shift-O, or by using the Up Arrow and Down Arrow keys to move from one sequence edit point to the next.

  3. Zoom in to the clip as far as possible.

    Figure. Audio tab showing the clip zoomed in as far as possible, so that the playhead is the width of one video frame.
  4. Hold down the Shift key as you drag the playhead to the exact place where the click occurs.

    Figure. Audio tab showing the playhead moved to the location of the click.
  5. Click the Level Keyframe button and reposition the playhead to place two keyframes at the beginning of the click and two keyframes at the end of the click.

    The two inner keyframes surround the problem samples, and the two outer keyframes are placed a few hundredths of a frame outside of these.

    Figure. Audio tab showing keyframes surrounding the problem samples.
  6. Drag the part of the audio level overlay between the two inner keyframes down until the box indicates –60 dB.

    Figure. Audio tab showing the section of the audio level overlay between the two inner keyframes dragged to the bottom of the waveform.

    The unwanted noise should be gone, and the rest of your clip’s audio is not affected.

Example: Using Keyframes to Control Pan

Setting keyframes to change pan dynamically works the same way as setting keyframes to change levels dynamically. You need to set at least two keyframes to effect a change over time.

Changing pan over time is often done to achieve stereo effects such as making a car sound zoom from left to right, or putting a particular sound effect on one side or the other of a stereo image. If you want the car sound effect in your edited sequence to zoom from the left to the right to match the movement of an onscreen car, here are the steps you would take.

To set up a dynamic stereo pan using keyframes
  1. Open the car sound effect in the Viewer so you can see it in more detail.

    Figure. Audio tab showing the waveform of the car sound effect.
  2. Move the Viewer playhead to the beginning of the car sound effect’s waveform, right before the car sound starts playing, and click the Pan Keyframe button to set a keyframe.

    Figure. Audio tab showing the playhead moved to the beginning of the car sound effect so a pan keyframe can be set.
  3. Drag the Pan slider all the way to the left, so that the sound starts playing out of the left speaker.

    Figure. Audio tab showing the Pan slider dragged all the way to the left.
  4. Now, move the playhead to a position after the car sound effect has finished playing.

    Figure. Audio tab showing the playhead positioned at the end of the car sound effect.
  5. Drag the Pan slider all the way to the right, so that the sound ends playing out of the right speaker. Because you’ve already set a keyframe for this clip, dragging the Pan slider at another point in the clip automatically produces a new keyframe.

    Figure. Audio tab showing the Pan slider dragged all the way to the right and the pan overlay sloped to show a change in pan from left to right.

    When you play back the clip, you’ll hear the car sound move from left to right.