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.
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.
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.