Program notes for:
"Jours heureux à l'atelier"

a short algorithmic composition by Stéphane Rollandin (hepta@infonie.fr)


	This is a MIDI piece for piano and drums, composed with GeoMaestro, a KeyKit plug-in that I developped over the last year. The basic principle of GeoMaestro is to represent sounds or notes as static events in a plane, which can be projected onto a segment or a circle drawn on that plane. Moving along the segment or circle at a given speed thus plays the projected notes in a time order decided by the geometry of the projection.

	Composing with GeoMaestro happens at different levels: choosing and positioning notes or sound events; choosing and articulating the different projection supports (segments and circles); defining distortion procedures, so that the actual sound or pitch of an event, when projected, does also depend on its relative position with respect to the support.

	In "Jours heureux à l'atelier", the musical events are three piano 'a' notes (midi 69) and four "drums" notes, actually basement noises from an excellent SF2 soundfont by Erik Hermansen: only seven events all together. The projection is done on a rectangular area analog to a billiard table: given two points inside the rectangle, GeoMaestro generate a trajectory by assembling segments so that they bounce at the borders of the table. In this composition, a regular shift in the bouncing angle is programmed, so that the trajectory is not actually a pure billiard table one. It is made out of 214 segments whose musical lengths range from 0 to 2.125 seconds. The distortion procedure is as follows: events volume decreases exponentially with the distance; piano notes obey a pitch shift proportional to their distance and depending on their relative side: an event located at the left of the segment has a decreased pitch, while an event at the right has an increased pitch. 

	

	Details and images are available on the web at this address:
	 http://perso.infonie.fr/hepta/GM/compos/GMmusic.html  

	GeoMaestro is released under the GPL and can be downloaded at this address:
	 http://perso.infonie.fr/hepta/GM/eGM0.html  




	Stef

	(February 19, 2001)