Could I create a video of exactly what I would like to do and email it to you John?
It is kinda hard to explain via messages as interpretation can be mixed..

Very very cool what you are doin with the daisy chain LEDs by the way

An interesting trick would be extracting both a color and an intensity value from each MIDI note message.

Of course, intensity may not matter that much. We could just map the note velocity to a specific color palate (warm, cool, ‘bone,’ rainbow, etc), similar to how old-school video games graphics were done.

And if so, could MIDI messages also dim each individual node colour?

It seems that your MIDI messages are only triggering the LEDs to put out maximum brightness on each RGB of an individual node producing only white in the video above.

put the piezo triggers in your 8′ mock-keyboard – and then you can “play it” too

you could even make a massive, plywood keyboard and put the piezo’s embedded in it per key and you can stamp-to-play (ah-la tom hanks in the movie “big”)

take it a whole other way and “Decorate” a drum kit with your pixels – and put the triggers on the body/head(somehow) – and make your lights dance based on your midi-trigger.
Would have been a hit in the 1980′s!

Just an idea or two to expand on
Mike

It’d be possible but computationally expensive.

In the 70s, they did it using a handful of analogue filters; the resulting creature was called a ‘Color Organ,’ which would flash different bulbs in sync with low, middle and high components of the music.

http://en.wikipedia.org/wiki/Light_organ

Today I’d attack it using an 80- or 100-bin fast Fourier transform,

http://en.wikipedia.org/wiki/Fast_Fourier_transform

reducing the audio input into groups of frequency bands, each with varying intensity.

There’s a good chance that these folks

http://www.intelliscore.net/

are doing something similar with their .wav to .MIDI conversion utility.

Doing this sort of math ‘live’ is a non-trivial exercise in signal processing.

That being said, the Madrix software used in the above clip does include some nifty music-to-DMX effects. None are so sophisticated as to chop an audio input into 88+ frequency bands, but there’s a lot that can be done to existing graphics routines if they are ‘kicked’ from time to time by a bass drum.