Submissions to SHA2017 are out

Allthough SHA 2017 is too expensive for what it is (OHM 2013 was not particularly well organized), I decided that if they pay my entrance ticket I will still participate. I proposed two/three events.

First a talk on Zathras titled: “Time Stretching BpmDj – 8 Secrets the Audio Industry does not want you to know. Nr 5 will shock you.”

Time stretching of audio tracks can be easily done by either interpolating missing samples (slowing down the track), or by throwing away samples (speeding up the track). A drawback is that this results a pitch change. In order to overcome these issues, we created a time stretcher that would not alter the pitch when the playback speed changed.

In this talk we discuss how we created a fast, high quality time stretcher, which is now an integral part of BpmDj. We explain how a sinusoidal model is extracted from the input track, its envelope modeled and then used to synthesize a new audio track. The synthesis timestretches the envelope of all participating sines, yet retains the original pitch. The resulting time stretcher uses only a frame overlap of 4, which reduces the amount of memory access and computation compared to other techniques.

Demos of the time stretcher can be heard at
The paper that accompanies this talk is at

We assume the listener will have a notion about Fourier analysis. We do however approach the topic equally from an educational as well as from a research perspective.

Then I proposed to play 2 DJ-sets with BpmDj. In itself interesting because I did not play anything the past 10 years. So I had to sell myself somehow.

Dr. Dj. Van Belle, a psyparty DJ who has his roots in the BSG Party Hall (Brussels/Belgium, 1998). After playing popular tunes for them students, he decided to throw in some psytrance… And absolutely no new style was born. He started his trend to be as inconspicuous as possible. In October 2006 he surfaced at the northern Norwegian Insomnia Festival. As an experiment, he played all songs at 85% of their normal speed. Every time he saw a camera, he inconspicuously hid behind the mixing desk. Since then he has done absolutely nothing. His career is as much a standstill as psytrance was between 2000 and 2016. And this makes him the perfect DJ. Bring in some of them good old beats. Some nostalgia for y’all. An academic approach to the real challenge on how to entertain them phone junkies.

Nowadays he plays anything he can get his hands on, mainly to test the DJ software he made. Some of his mixes can be found at

I’m curious what they will accept (if anything).

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