4 Replies Latest reply on Sep 14, 2011 7:18 PM by Rick Gerard

# Audio to Keyframes Question?

I want to use the Audio to keyframes assistant to make a Knoll light brighten to the beat of the song, but if i parent the Audio Amplitude Layer to the 'Brightness' on the Knoll light creates, the Knoll light is very dark, because the "both Audio" keyframes are around 20, where as the Knoll light needs to bounce around 100.

So basically im asking if there is a way to have the Knoll light bright enough, while still using the Audio to Keyframes. Thanks!

Specs - After Effects CS5

Win 7 64 Bit

• ###### 1. Re: Audio to Keyframes Question?

You could use the linear expression method to map the range 0-20 from the audio levels to the 0-100 range (or whatever you want) for the brightness property.

• ###### 2. Re: Audio to Keyframes Question?

As Todd said, it's a linear expression. It looks like this:

```linear(value, 0, 20, 10, 100)
```

To understand it start at the first bracket and carefully read this sentence.

(take the value of your first variable, from a low of 0, to a high of 20, and create a new linear range of values from a low of 20, to a high of 100)

You could also write the expression using ease instead of linear. It just changes the graph from a line to a curve.

To make the whole thing work you have to apply expression to the light value of the Knoll light value and define the value as a variable using the Both Channels Slider generated with the Audio to Keyframes assistant.

The finnished expression would look like this:

```val = thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider");
linear(val, 1, 20, 20, 100)

```

Did you follow that? val is the variable for the value of the audio keyframes both channels slider. You can't use value for the variable because it's a reserved word.

• ###### 3. Re: Audio to Keyframes Question?

Thanks! that worked great, but I have one more question, Is there anyway to make the keyframes stronger? Like the brightness doesnt change very much, it just sits around 100.

• ###### 4. Re: Audio to Keyframes Question?

Scroll through the audio keyframes and check the values. If they run from about 4 to about 15 and you want the brightness to vary from say 30 to 200 then change the expression to those values. IOW

liner(val, 4, 15, 30, 200)

Check by moving the CTI to a keyframe with a value of 15. The new brightness value should be 200.

You can see the range of values by exposing the graph editor. Check out this screen shot. My audio values go from 0 to about 21.5.