Well it is pretty much 2 sin waves added up ..

If you can look past my horrible coding you can find it in index.html in the block from 762 and 775 ( includes comments of another animation ) .

Note:
- Do copy the code to your own projects folder to avoid any translation updates from overwriting your own code.
- Audio data goes from low to high frequency in 64 values, total is 128 values. So 0-63 is left channel i believe, and array indexes 64 - 127 the right. When you are showing more bars then other values are automatically determined using cosine interpolation.
- I believe in this wallpaper I split the normal audio from the idle one so normalization should not affect it.
- The code is really really sloppy, almost no comments, and commented bits that don't even belong in there :)

thanks for the prompt reply, and thanks for making such a cool wallpaper in the first place!

if anyone wants to try what I came up with, just replace the section of code Squee mentioned with this:

var p = performance.now()/(7000);
var p2 = performance.now()/(10000);
var v = 0.1*((((Math.PI*Math.cos(p))-(2*Math.PI))*Math.cos(((Math.PI*Math.cos(p2))+(2*Math.PI))*(i+50)/3))+(((Math.PI*Math.cos(p2))+(2*Math.PI))*Math.sin(((Math.PI*Math.cos(p))-(2*Math.PI))*(i+50)/3)));
data = v+0.2;
data[i+64]= -v+0.2;