This chapter is from the book
This chapter is from the book
This chapter is from the book
Adding the finishing touches
The layers work pretty well with the underlying video, but they’ll blend more convincingly if you change the blending modes. You’ll also add the audio file.
- Click the Toggle Switches/Modes button at the bottom of the Timeline panel.
Choose Multiply from the Mode menu for all the layers except the Checkerboard layer; choose Overlay for the Checkerboard layer. (You won’t be able to change the mode for the Spiral layer, because Collapse Transformations is selected.)
- Drag the Melody.aif clip from the Project panel to the bottom of the layer stack in the Timeline panel.
- Press the spacebar to enjoy your creation! When you’re done previewing the project, save your work.
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Extra credit
Animating layers to match audio
Currently, the spiral shape turns in a slow circle. The movie will be more compelling if the size of the spiral is animated to match the beat of the music. You can scale the spiral in time with the amplitude of an audio file. First, you need to create keyframes from the audio information.
- Select the Spiral composition in the Timeline panel. Drag the Beat.aif file from the Project panel into the Timeline panel, and place it beneath the Spiral layer.
- Right-click or Control-click the Beat.aif layer, and choose Keyframe Assistant > Convert Audio To Keyframes.
After Effects adds the Audio Amplitude layer. The new layer is a null object layer, meaning it has no size or shape and won’t appear in a final render. Null objects let you parent layers or drive effects.
- Select the Audio Amplitude layer, and press E to display the effects properties for the layer.
Three categories of effects properties are available for the layer: Left Channel, Right Channel, and Both Channels. You’ll work with the Both Channels category.
- Expand the Both Channels category.
When you converted the audio to keyframes, After Effects created keyframes that specify the amplitude of the audio file in each frame of the layer. You’ll sync the scale of the spiral to those values.
- Select the Spiral layer, and press S to reveal the Scale property for the layer.
- Alt-click (Windows) or Option-click (Mac OS) the Scale stopwatch to add an expression. The words transform.scale appear in the time ruler for the layer.
- With the transform.scale expression selected in the time ruler, click the pick whip icon (
) on the Expression:Scale line, and drag it to the Slider property name in the Audio Amplitude layer.
When you release the mouse, the pick whip snaps, and the expression in the shape layer time ruler now reads temp = thisComp.layer(“Audio Amplitude”).effect(“Both Channels”)(“Slider”); [temp, temp, temp]. (You may need to click the expression to see the full thing.) This expression means that the Scale values for the shape layer will depend on the Slider values of the Audio Amplitude layer.
Note: You’ll learn more about expressions in Lesson 6.
- Choose Edit > Deselect All to deselect the layers. Then move the current-time indicator through the time ruler to see the spiral resize with the audio’s amplitude.
The scale definitely changes, but sometimes the spiral disappears. You’ll modify the expression so that the spiral remains visible.
- In the time ruler, click the expression to make it active. Click an insertion point at the end of the first line, between the closing parentheses and the semicolon. Type +90, and then click an empty area of the Timeline panel to accept the change.
- Preview the composition, and watch the spiral pulse to the beat of the audio file.
- Return to the Tracking composition in the Timeline panel. Then press the spacebar, and watch the spiral pulse as the camera moves through the scene. Save your work.