Library or method to obtain audio playback data? Hz, Amp, etc

I’m looking to create a project to visual audio. I obviously need audio to do that.
I’d prefer to have it work with the system audio. But being able to input a mp3 or even a YT link.
Any starting points?

check on MINIM lib
and its FFT examples.

example how my current projects looks like

  • signal graph
  • FFT graph (with mouse over bar / frequency show )
  • mixing and volume sliders ( handmade )