ICMC 2008 Belfast

I spent last week in Belfast attending the 2008 ICMC. Here's the view from the flat in which we stayed...



There was a very full concert schedule as well as a really diverse and well-paced academic program. There are of course a few papers that seemed to really standout. Maybe I'm falling for a bit of a gimmic, but I was really impressed with Nick Collin's generative music system Infno. The system basically generates electronic dance music automatically. The few examples Nick generated live during his talk were actually really impressive - strong in melody and rhythm but very much lacking in sound design. Nick suggested that his generative electronic dance music algorithms could be used to create "ground truth" data for MIR classification tasks - a very interesting idea but there be dragons.

George Tzanetakis gave a nice demo of Marsyas-0.2. I briefly looked at Marsyas a long time back but never really used the stuff. Now that George has created some really nice Python bindings, I think Marsyas is going to become a big part of my work. George demonstrated the bindings by doing some live coding in Python - haha, take that you mother Chuckers!!!

Bob Sturm from UC Santa Barbra quite deservingly won the best paper award (sorry can't find the PDF online). Unfortunately, I missed the talk (@9am) but there seems to be a lot of buzz around the "atomic decomposition" method he uses for analysis and synthesis of audio. I reckon this will become a hot topic in the MIR community.

Also, the SoundSpots installations by Rob van Rijswijk and Jeroen Strijbos was my favorite artistic piece of the conference. A series of parabolic speakers are hanging from the ceiling such that you can only really hear the spearkers' output when standing directly below them. Additional loud speakers around the room are playing one of several brilliant compositions artfully crafted specifically for the installation - truly a top-notch sound installation.



And finally a big-up to Henry Penttinen, Nick Bryan, and the rest of the CCRMA kids for the Mobile Phone Orchestra. Brilliant.

Piano Lab - andrew robertson

Mr. Robertson jams on piano guts
Piano Lab 01

the piano lab
Posted via Pixelpipe.

A strange and wonderful flower

Can anybody help me identify this lovely flower that just bloomed a few weeks ago in my garden? I've recently moved to a new flat and the previous tenant was obviously an avid gardener. I feel obligated to do my part to maintain where I can...




I feel like maybe this is a plant that is not really at home in the London climate. Will it die in the winter? I can't bring it inside as it is definitely planted directly in the garden...

Periodic spectral re-ordering of genre tags based on network structure

Phew!!! that title is a mouth-full. But basically all we're doing here is re-ordering the list of genre tags found on myspace based on ''top friends'' connections. If people who tag themselves as ''Death Metal'' tend to have friends who tag themselves as "Grindcore" then these genres will appear close to each other in the list. Follow the link for an interactive scroll through the genre list (sorry couldn't sort out embedding the processing applet in blogger :/)



- scrolling list from 'friendship' network structure
- scrolling list from co-occurrence network

We use the same methods that are sometimes used to organize nodes in a graph for visualization. Here are nodes are musical genres and our weighted edges are defined by the number of myspace artist friendships span any pair of genres. Alternatively we can use ge In the first step, we build an adjacency matrix of genres A. If artist i and artist j are ''friends'' in our myspace sample, we add one count to A(i,j) and repeat for every artist in our sample space. Once we've completed our adjacency matrix we perform a spectral re-ordering. Conceptually, we want to move the non-zero values in our matrix to the diagonal. Viewing this directly as an optimization problem is intractable for very large matrices, but we can use an eigenvector approach to make things faster.

Turns out we can be even a bit more clever and try to move non-zeros to either the diagonal or the off-diagonal corners. This is periodic spectral re-ordering and requires us to calculate a normalized Laplacian as well as a subdominant eigenvector pair. The 'friendship-based' genre list above is generated using this method. Below you can see the original and periodically re-ordered adjacency matrix:



After the adjacency matrix is re-ordered, we actually have a re-ordered list of genre tags. The tags that have more 'friendship' connections in the network get moved closer together in the list. You may notice the results aren't perfect. Keep in mind we have a small sparse sample and the distribution of genre labels follows nearly a power law - ''Hip Hop'' and ''Rap'' are much much more common than ''Chinese traditional'' or ''Showtunes'' for example. With a larger dataset (we're using about 19k artists here) the genre listing might improve - moving conceptually similar genres closer and dissimilar ones further apart. As it stands we have some interesting combinations - ''Southern Rock'' and ''Chinese Pop'' can be found directly adjacent to each other in the list. Note, however, that these genre tags appear 113 and 39 times respectively while the ''Hip Hop'' tag occurs 25,536 times.

Note we also construct the genre tag adjacency matrix based on co-occurrence - if an artist is tagged as ''Tango'' and ''Salsa'' put a count in the corresponding row/column of the adjacency matrix. Then we have a genre list based on genre tag co-occurrence. Although it is difficult to quantify, this seems to provide a slightly better listing. Perhaps this is a more coherent list than the one created using the friendship network - not as many unusual pairings in the order. What do you think?

Special thanks to Gabriella Kalna from the University of Strathclyde for the periodic spectral re-ordering Matlab code.

Happy Flu

I'm breaking my non-blogging streak with the Happy Flu. Add this to your own blog and become part of the epidemic ;)

NetSci 2008

Oh boy have I been busy. Last weekend I was at the Mashed hackfest with Yves and Ben. We did a nice little hack to link personal audio collections to BBC radio shows (see Yves' blog post and Ben's) . Not so sexy compared to some of the other hacks but we did get some blog nods.

Then on Tuesday, I took the train to the lovely and charming East Anglican city of Norwich for the NetSci 2008 conference. It was a really great cross-discipline meeting of minds - people working on problems in molecular biology, physics, sociology, politics, (ehm) music, and probably others I'm forgetting. And guess what - everybody is using network science to tackle all these diverse problems.

I gave a talk about the topology of the Myspace artist network (pdf slides). In the same session there was a nice talk from Anmol Madan (MIT Media Lab) about the Mob Media system which uses hacked iphones to track face-to-face interactions and music sharing habits in a real-world social network. Really interesting work. Also in the same session a nice talk from Annelies Kamran on Networks in Global Politics and a talk from Mason Porter on Communities in the US Congress.

I was also really excited by the periodic spectral re-ordering (pdf) methods presented by the lovely and brilliant Gabriella Kalna from the University of Strathclyde. I have some nice plans to apply these methods to social tags and genre labels (stay tuned for the exciting conclusion;)

The Giant Instrument

This week C4DM Presents completed work on our sound installation for Shunt Lounge called the Giant Instrument. The concept is you play the instrument by moving in and out of these spotlights. I wanted to give the users a really fun interactive experience and sort-of recreate the feeling you get when you first learn to play a musical instrument. The work was a collaboration between Andrew Robertson, Adam Stark, Jean-Baptise Theibault, Steve Welbourn, and myself. The team really came together and pulled off something great in a short time - exceeding all expectations. Chris Frauenberger and Stuart Battersby took some really great pics of the installation.