do you know if i could do the same thing --> control led lights using a playlist of say 3 songs in max/msp and then sending it to arduino to change the led colors?
I'm not familiar with max/msp, I just got Arduino 2 weeks ago. Any analog signal will work with this program regardless of the source. To get bass isolated you would still need to create a filter before the signal is put into the Arduino since the code only performs actions based on amplitude and doesn't do any filtering. I looked up max/msp and plan to mess with it in the near future so if you still have trouble I may be of more assistance later.
Unfortunately not actually beat detection, I was kinda hoping for some true 'beat detection' code which is extremely difficult.
Yes, but I couldn't think of any good reason to actually detect the beat pattern of music, if you want to play different songs or very dynamic music a program that detected beats would not be very useful. This program allows for rapid change in music intensity and rhythm and will still perform actions based on the bass hits as long as you have a halfway decent filter.
I can add a few lines of code to estimate BPM if you were looking for something like that. If you have an awesome project idea that requires being able to estimate the upcoming beats in music before they are played then you can let me know and maybe it will inspire me to take up the coding challenge, for the projects I have in mind though this is all I need.