Converting Audio Into Keyframes

For any of the following work flow, you first need to create your keyframes. Import the Audio track you wish to use and place within a composition. Right click the audio track in the timeline and choose Keyframe Assistant/Convert Audio to Keyframes. This creates a Dummy object in the center of your Comp with 3 sets of Slider data (Left, Right, and Stereo channels) in the timeline. Unless you need to separate the signal left from right, you can delete all but the Stereo slider.

Pumping and Shaking the Background

First we will animate the scale of the background. Import a background image that is at least as big as your Comp. Solo its Scale property. Alt-click on its stopwatch. Use the Pickwhip that appears as part of the expression track by clicking and dragging to the slider track in the audio. You will see this expression:

temp = thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider");
[temp, temp]

The results will scale that background image between 0 and 100% which is way too extreme for this effect. You can divide the power of this expression by adding a / and a value. let's divide by 5 by adding /5 immediately after ("Slider") and before the ; Now we can add the starting value (scale) of the image by typing value+ before [temp, temp]. The expression now reads:

temp = thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider")/5;
value+[temp, temp]

If you need to smooth out the pumping, you can add an Expression onto the Stereo Slider. Alt-click on the Slider Stopwatch and in the Expression line type: smooth(.1,21) -in this example, the .1 refers to the time (.1 seconds) with smaller values getting too accurate and reintroducing jerkiness. The 21 refers to samples of audio, with larger amounts being more smooth.

To amplify this effect we can also animate the position of the background. Make a note of the Position values for X and Y. Alt-click on the background's Position stopwatch and connect the Pickwhip to the Stereo Slider track. You will see this expression:

temp = thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider");
[temp, temp]

Replace [Temp, Temp] with the X, Y values you noted above. Add a Wiggle expression by typing: ;wiggle(temp, temp) The 2nd line of the Expression should read (with X and Y replaced by position values):

[X, Y};wiggle(temp, temp)

You should now have a rockin background. These techniques can be used to animate the Scale and Position - virtually any property that can be animated - of any footage file, but the tweaks will be specific to the audio file used, the size of the footage, and the intensity of the effect desired.

Next