I wonder how much Markov-chain modeling would be appropriate for this. I mean, if music is a language, then why not analyse it using Natural Language Processing (NLP) techniques like Markov's... :-)
I'm not familiar with Markov-chain modeling, but it might be an interesting endeavor to try to describe genres of music using first order logic ;). I suppose any of these methods could work, it's just a matter of which is easiest, and describing musical genres using logical assertions sounds even more difficult than trying to do it in natural language, which has already proven almost impossible, esp. with 20th century music.
A lot of people say that music is a mathemetical language so a more mathematical approach may tend to be more efficient. Then you can leave the details up to the algorithm, once you've given it the tools to analyze the music and a thousand pre-defined songs as guidelines. But I guess that's exaclty what looking at it as natural language, and analyzing it with Markov chain modeling would be. Once you've defined your language of notes, measures, tempos etc (a much smaller vocabulary than traditional natural language) you could let the modeling search go at it. Or something. I only have a cursory understanding of AI, and all my practical knowledge is limited to search techniques and propositional logic. I'm just musing at this point. Now, we just need to do this all on the fly with my new extern [genrefi~] :) It takes a signal input and outputs the song's genre and aesthetic quality on a scale of 1-10. You can watch your quality rating go up and down as the song progresses. I'll never write a bad song again.
Actually, when I have some time I was thinking of sitting down and writing an algorithm that chops up sound files and reasembles them. It would base its 'choices' on some desired attributes (bpm, climactic placement, choppiness/smoothness (1-10) etc.) and on some vague definitions of what is 'good' and 'bad' music. The idea is that I could feed in any sound file, eg. birds chirping, or some abstract ambient improv and it would cut it in such a way that it becomes a structered, rhythmic song of some sort. Really more of an excercise in genetic algorithms than anything practical.
-i