After Effects what does this script do?

[MurmilePie]

After Effects Tutorial: Audio Spectrum Effect [Trap Nation] - YouTube

I'm doing a couple of intros on After Effects and I'm pretty new to it. In the video above, this script, value + (comp("Music").layer("Audio Amplitude").effect("Both Channels")("Slider"))/10 is used along with value + (comp("Music").layer("Audio Amplitude").effect("Both Channels")("Slider"))/30 and value + (comp("Music").layer("Audio Amplitude").effect("Both Channels")("Slider"))/5 .

Times they are mentioned:

11:08

Why? I've made another video without using those scripts and it turned out fine for the particles and such. What do they do?

[Nexahs1138]

Expressions just make things easier to do, instead of you having to keyframe these things it does it for you.

Go to videocopilot.net and look in their early tutorials for a list of expressions and helpful tips

[MurmilePie]

Thanks for the reply but I'm still a bit confused.

Because after I input the script the tutorial video just has us save it then we render.

What exactly is the script/expression doing to the particles? Telling them when to bounce at a specific time?

Also thank you for the tutorial site!

[Horshack · Accepted solution]

That specific expression is taking the initial value of that property ("value") and then adding to it the value defined by the Expression Control slider (with some scaling/arithmetic applied to the slider's value, ie the "/10" and "/30")

[Horshack]

Start here:

Dan Ebbert's intro to AE scripting