VU meter.

Hey guys,

I want to build an LED VU meter. I'm talking about an actual VU meter, not just some blinky leds to the music. I'd like adjustable attack and decay. http://en.wikipedia.org/wiki/VU_meter

Is the arduino powerful enough to process audio in software?

Input would be from a 3.5mm headphone jack.

You only need to measure the amplitude of the input audio which would be no problem to the Arduino. The input from the ADC is 10 bits. If that would give sufficient range for your intended application then it should be easy enough to do.

Pete

Anyone have the relevant math equations handy?

Look in this topic: http://arduino.cc/forum/index.php/topic,80070.msg605236.html#msg605236 You can adjust attack/decay time changing averaging constant.

Panici: Anyone have the relevant math equations handy?

No, but keep in mind you have/need three results you are looking for:

Attack time decay time Logarithmic amplitude display value.

A true VU display is a logarithmic scale from 0 amplitude to typical +3db where 0db is some standard reference value as shown here: http://en.wikipedia.org/wiki/VU_meter

If you just display a linear scaled value from the analogRead() value you will find that you will be able to display only a very narrow range of volume and most likely you will be very disappointed with the effect.

Lefty

Try this:
http://telecoreference.wordpress.com/2012/03/20/vu-meter-con-arduino/