And what if there is not a constant tempo?
If you know the score, you can more easily find beats and tempo (and do score following). For instance: http://repmus.ircam.fr/antescofo
If you know the score, you can more easily find beats and tempo (and do score following). For instance: http://repmus.ircam.fr/antescofo
The IRCAM research you link to looks really interesting, and I think it would be useful for other purposes, like real-time performance with automatic accompaniment.
You can assume that the most prevalent duration is a quarter note, but it is not always what would be on the score.
But it's more a problem related to transcription than to DJing (where the representation of the beat as a whole note, a quarter note, or anything else is eventually not important, I think).