adafruit_support wrote:2 - No quick answers for that one. It really depends on what you want to do with the audio.
since the computing power of your computer is pretty near infinite compared to that of the arduino, it might be best to analyze the audio on the computer and pass data over usb to the arduino telling what to do with the lights.
davnirvana wrote:1a. What is the maximum amount of LED's that can be connected to an Arduino UNO? [I've been getting varied answers all over the internet]
what sort of control do you need over the leds. just on/off, variable brightness, rgb? and how many might you conceivably want? you've got 20 i/o pins on the arduino. let's say you want the uart and one analog pi left available. i've managed to get 8 bit pwm on 18 arduino pins to get 24 bit control of 6 rgb leds. you could multiplex a 9x8 array and get on/off control of 72 leds. you could charlieplex a 17x16 array of, (er, excuse me a moment), 272 leds. problem is the multiplexed solution gives you a 12.5% duty cycle and the charlieplexed one gives you 6.25%. you might want things a little brighter than that.
you can introduce shift registers to multiplex larger numbers of leds at higher duty cycles.
you can use specialized led drivers like the one used on the pwm/servo driver mentioned above.
reading further down this list there is a correlation to higher costs, which brings us to...
the digital rgb pixels or strands. these are really cool and easy to use, but the cost is close to $1/led. i love my lpd8806 strand, but i don't see getting it a brother or sister any time soon.
davnirvana wrote:3. What kind of code is available to have the LED's react to frequency, volume?
still think you ought to do the grunt work on the host and let the arduino stick to driving leds.
"If I had known it was harmless, I would have killed it myself." - Phillip K. Dick, A Scanner Darkly