Classical Convert

Spiral Tonality

Evening all.

One nice feature of having a decent collection of blog posts up and active is that every now and then someone leaves you a nice comment on a piece you had pretty much forgotten about. Today this was a comment from chaika, who commented on this post back from the depths of last year in which I really, really wanted a piece of software which would automatically display the tonality of a piece of music as it progresses.

Miss/Mister commenter provided me an excellent lead on the subject: Elaine Chew at USC has published a bunch of papers which attempt to do exactly that. Not only are her papers relevant, but via her references I can now work out all the other important writings on the subject. Awesome.

So far it seems that her method for determining tonality is based on a spiral:

In which each point on the spiral is a major fifth higher than the last (and so each point vertically above ends up being a third higher, which is why those chords look like triangles, because it’s a point connected to a spiral-neighbor and a vertical-neighbor) That spiral looks kinda complicated, I know, and I’m feeling the pain a bit because I only know the most basic music theory. However, I’m fairly determined to get to grips with the ideas in this paper, and it’s actually a rather interesting (and effective) way to learn the theory for me: backward from the math.

Tags: music, tonality, visualization

Hot Tuesday Linkage

Janacek would be proud. No, wait a sec, Janácek (check out the text decoration on that bad-boy… except the c doesn’t work properly. Darn.) would be proud. Someone (namely a dude called Ranjit) has a proposal for an installation piece which you can see in the following video:

installation proposal for artbots 2008 from ranjit on Vimeo.

It’s a robot which translates vocal patterns into musical sounds which it performs on a modified electric guitar and various pieces of percussion equipment. In the video linked above you can see how it interprets a brief scene from Citizen Kane. This is exactly the kind of thing that Janacek was into, apparently; trying to mimic the cadences of the human voice using instruments. Except without the electric guitar and microchips. Probably.

Additionally, reader Yvonne forwarded me a recent story about an attempt to geometrically visualize the structure of musical works. As regular readers are probably sick to death of hearing, I’m totally in love with the concept of theoretically-well-grounded visualization techniques. It’s a fairly holy grail. This press piece is tantalizingly light on exact details, but one of the most interesting tidbits for me was:

To some extent, we can represent the history of music as a long process of exploring different symmetries and different geometries.

Which I’m a tad suspicious of due to the “certain extent”, and might just mean that they got some pretty pictures which sort of look similar, but could be really neat. If I feel brave enough I’ll try and dig up the actual paper sometime this week and wade through acres of musical and mathematical theory which I do not understand. I can pretend to though. I’m getting really good at that after four years in grad school.

Tags: classical music, janacek, visualization

Visualization Via Video

Yuck, been sick these last few days with not-wanting-to-eat feelings thrusting their unpleasant paths through my abdomen. Bastards. Now it’s magically altered itself (or they … themselves, the plurality of this anthropomorphizing is not well defined) into an annoying pain of a pain in my hip. Clearly I am a wreck and destined to be crumpled into glue ever so soon. Anyway, not to skip around the topic of choice: I’ve updated the previous visualization work into video form. Check this out:

It’s at least passably interesting, isn’t it? Mostly I’m just relishing and wallowing gleefully in a minimal amount of proudness for working out how to animate a bunch of pictures with a line down the middle…

My (less disappointing!) Visualization Efforts

Aha! This round of music visualization is going somewhat better than then last incarnation. Instead of a crappy bunch of graphs I now have a totally official and fancy-pantsy looking spectrogram going on, albeit in a static not-yet-animated form. Here is what the first 120 seconds or so of the second movement Beethoven’s piano sonata op. 111 look like (click for the full version, the image below is a small section at the start):

This shows the dominant sound frequencies present in the music, over a period of time. These frequencies correspond in a not completely linear way to the notes which are being played. This lets you see the shapes of the melodies as the piece progresses (from left to right in the spectrogram). I think with cleverer coloring, and animation, this will become much more apparent. Still, not bad for a first, errr, second try!

The recording I am using is from the wikimedia page on Beethoven. The software I am using to create it is all open-source: sox, python, numpy, pil.

My (somewhat disappointing) Visualization Efforts

Hmmm. Music visualization is a pain in the arse. I’m simultaneously attempting to produce a real-time frequency visualizer type dealie, and learn Python (which is what all the cool kids are using for programming) making it way, way harder than it should be. Since it takes flipping ages to calculate all the necessary Fourier transforms it seems best to produce videos of the visualization, instead of trying to do it in real time. Which is probably impossible. Currently they look pretty, errr, lacking. Prettying things up is probably going to be the largest part of the problem.

At the moment each video frame looks like this:

See what I mean? In the next few days I’ll play around with graphics routines to try and generate a proper spectrogram. Then we’ll be in a bit more business.