DBTune blog

I was at Mashed (the former Hack Day) this week-end - a really good and geeky event, organised by the BBC at Alexandra Palace. We arrived on the Saturday morning for some talks, detailing the different things we'd be able to play with over the week-end. Amongst these, a full DVB-T multiplex (apparently, it was the first time since 1956 that a TV signal was broadcasted from Alexandra Palace), lots of data from the BBC Programmes team and a box full of recorded radio content over the last year.

After these presentations, the 24 hours hacking session began. We sat down with Kurt and Ben and wrote a small hack which basically starts from a personal music collection and creates you a playlist of recorded BBC programmes. I will write a bit more about this later today

During the 24 hours hack, we had a Rock Band session on big screen, a real-world Tron game (basically, two guys running with GPS phones, guided by two persons watching their trail on a google satellite map :-) ), a rocket launching...

Finally, at 2pm on the Sunday, people presented their hacks. Almost 50 hacks were presented, all extremely interesting. Take a look at the complete list of hacks! On the music side, Patrick's recommender was particularly interesting. It used Latent Semantic Analysis on playcount data for artists in BBC brands and episodes to recommend brands from artists or artists from artists. It gave some surprising results :-) Jamie Munroe resurrected the FPFF Musicbrainz fingerprinting algorithm (which was apparently due to replace the old TRM one before MusicIP offered their services to Musicbrainz) to identify tracks played several times in BBC programmes. The WeDoID3 team talked about creating RSS feeds from embedded metadata in audio and video, but the demo didn't work.

My personal highlight was the hack (which actually won a prize) from Team Bob. Here is a screencast of it:

I just got back from Beijing (I did a two weeks trip around China after the actual conference), where I attended the Linked Data on the Web workshop and the WWW conference.

The workshop was really good, gathering lots of people from the Linking Open Data community (it was the first time I met most of these people, after more than one year working with them :-) ).

The attendance was much higher than expected, with around 100 people registered for the workshop.

It started well with this sentence by Tim Berners-Lee in the workshop introduction:

Linked Data is the Semantic Web done right, and the Web done right.

That's a pretty good way to start a day :-) Then, Chris Bizer did a good overview of what the community has achieved in one year, illustrated by the different versions of Richard's diagram:

All the talks and papers were extremely high quality. I got particularly interested by some of them, including Tim's presentation on the new SPARQL/Update capabilities of the Tabulator data browser. This allows easy interaction with data wikis, where everyone can add or correct information.

I really liked Alexandre Passant's presentation on the Flickr exporter, which is highlighting a mechanism that I used for the Last.fm linked data exporter: linking several identities on several web-sites is just a owl:sameAs link away. Alexandre also did another presentation on MOAT (Meaning of a Tag), a really interesting project allowing to relate tags to Semantic Web URIs. For example, it allows to easily draw a link between my tag "paris texas" to the movie Paris, Texas in DBpedia.

I got a bit confused by Paul Miller's presentation about licensing open data. I have been aware of these efforts mainly by the work of the Open Knowledge Foundation and the Open Data Commons project, and I think these are truly crucial issues: we need open data, and explicit licensing. But perhaps the audience was not so well chosen: most (if not all) of us in the Linking Open Data community do not own the data they publish as RDF and interlink. DBpedia exports data extracted from Wikipedia, DBTune exports data from different music-related sources such as Jamendo or Last.fm, etc. The only data that we can possibly explicitly license are links (the only thing we actually own), and it does not have any values without any data :-) So I guess the outreach should mainly be done to raw data publishers rather than Semantic Web translators? But hopefully, in a near future, the two communities will be the same!

One of my personal highlights was also Christian Becker's presentation about DBpedia mobile: a location-enabled linked data browser for mobile devices., giving you nearby sights and detailed descriptions, restaurants, hotels, etc. We chatted a bit after the workshop with Alexandre and Christian about adding Last.fm events to the DBtune exporter to also display nearby gigs (with optional filtering based on your foaf:interests, of course :-) ).

Jun Zhao's presentation about linked data and provenance for biological resources was extremely interesting: they are dealing with problems strongly similar to ours in a Music Information Retrieval context. How to trust a particular statement (for example, a structural segmentation of a particular track) found on the web? We need to know whether it was written by a human, or derived through a set of algorithms, and in this case, we might want to choose timbre-based instead of chroma-based workflows in the case of Rock music, for example. This is the sort of things we implemented within our Henry software (more to come on that later, including online demo as soon as I put it on better hardware, and (hopefully) a PhD :-D ).

Wolfgang Halb did a presentation about our Riese project, but more on that later as I wrote the back-end software powering it and I'd like to give it a full blog entry soon.

I did a presentation about automatic interlinking algorithms on the data web, with a focus on music-related datasets. I detailed an algorithm we developed for this purpose, propagating similarity measures around web data as long as we can't take an interlinking (creating a bunch of owl:sameAs links) decision. This algorithm is good in the sense that it gives a really low rate of false-positives. On the test-set detailed in the paper, it made no wrong decisions. I blogged about this algorithm earlier.

Some people expressed concerns about the proliferation of owl:sameAs links (highlighted in this presentation by Paolo Bouquet). But I truly think it is a necessary thing, as long as web identifiers are tied to their actual representation. I need to be able to have a web identifier for a song in Jamendo and a web identifier for the same song in Musicbrainz, and I need a way to link these together: owl:sameAs is perfect for that. I wouldn't trust a centralised "identity" system (what actually is identity anyway? :-) ), as it would break the nice decentralised information paradigm we're implementing within the Linking Open Data project.

Anyway, lots of great people, a great time, lots of interesting discussions and new ideas... I am really looking forward for WWW 2009 in Madrid and the next workshop!!!

It has been a long time since my last post, but I was busy traveling (ISMIR 2007, ACM Multimedia, and AES), and also took some holidays afterwards (first ones since last Xmas... it was great :-) ).

Anyway, in my slow process of getting back to work, I finally wrote specification documents for the Timeline ontology and the Event ontology, that Samer Abdallah and I worked on three years ago. These are really early documentation draft though, and might be a bit unclear, don't hesitate to send me comments about them!

The Timeline ontology, extending some OWL-Time concepts, allows to address time points and intervals on multiple timelines, backing signals, video, performances, works, scores, etc. For example, using this ontology, you can express "from 1 minute and 21 seconds to 1 minutes and 55 seconds on this signal".

The Event ontology allows to deal with, well, events. In it, events are seen as arbitrary classification of space/time regions. This definition makes it extremely flexible: it covers everything from music festivals to conferences, meeting notes or even annotations of a signal. It is extremely simple, and defines one single concept (event), and five properties (agent, factor, product, place and time).

The following representations are available for these ontology resources:

• RDF/XML

$ curl -L -H "Accept: application/rdf+xml" http://purl.org/NET/c4dm/event.owl

• RDF/Turtle

$ curl -L -H "Accept: text/rdf+n3" http://purl.org/NET/c4dm/event.owl

• Default (XHTML)

curl -L http://purl.org/NET/c4dm/event.owl

And also, make sure you check out the Chord ontology designed by Chris Sutton, and the associated URI service (eg. A major with an added 7th). All the code (RDF, specification, specification generations cripts, URI parsing, 303 stuff, etc.) is available in the motools sourceforge project.