I want to make a speaker graphic 'wobble' to different frequencies..
Here's what I've done so far

I made a speaker graphic in a comp And I parented the scale to a null in the main comp

enter image description here

And I isolated the kick drum with a combo of a band pass filter and a bass-treble. Then I converted that audio into keyframes and pick whipped that null with that speaker's scale parented to it.

enter image description here

So here's where I'm stuck at:
I want to limit the speaker's scale within some values. Like the speaker should not exceed 75.8% and 76% of scale.

So what I tried so far is something like this ↓
temp = thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider"); [temp, temp] +[Math.min(73.8-2), Math.min(73.8-2)] [Math.max(23), Math.max(23)]

1 Answer 1


You need to do a linear map as an Expression. So the example below would take any value between 0-100 and map it between -100 to 100.

input = effect("Slider Control")("Slider");
inputLow = 0;
inputHigh = 100;
outputLow = -100;
outputHigh = 100;

  • Sorry I'm totally new to expressions, can you please show me how I put that into my rest of the expression?
    – user152435
    Aug 26, 2020 at 8:09
  • Edit - Thanks man, after you gave me a primer, I was able to find it on Google...
    – user152435
    Aug 26, 2020 at 8:39

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