Return type: Number or Array.
Argument type: t, tMin, and tMax are Numbers, and value1 and value2 are Numbers or Arrays.
In context, say you have the audio keyframe effect that goes from 0-100 and you want it to control the rotation of an object from -360 to 360.
in the rotation parameter of the object you would enable expressions first. Then pickwhip to the audio keyframe effect to get something like this
thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider")
Now you need to assign this to a variable, let's say x, so it becomes
x = thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider")
This will give you simple rotation between 0 and 100 degrees, not the full range of movement. So then you add the linear expression underneath like so:
linear(x, 0, 100, -360, 360)
The coolest thing about this is that it is basically a built-in falloff / threshold control. So say you don't want to trigger rotation until the audio comes up to a certain level, say 15 dB, and then cut off at a max of 80 dB because the audio never gets above that, you would write instead:
linear(x, 15, 80, -360, 360)
So this squashes the input range to 15-80 while still outputting the full range of rotation
You can also use ease(x, n, n1, n2, n3) for a smoother output, but I'd start with linear() first
You can easily do this with any variable, even array variables like color or 3D coords...
