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I have to do a 2 minute piece putting audio to a constant evolving particle swarm that moves from small to large and rotates. I believe the best way forward is to perform this via some form of synth/sampler i.e. Kontakt/Alchemy
Firstly, I would suggest giving a more detailed explanation as to your needs. Will you be performing this yourself or is this more along the lines of installation art? Will it be interactive and thus, non-linear or will it be a linear piece? What is your time-scale / deadline?
Max MSP is a tool often used by sonic artists that offers enormous flexibility. However, it takes quite an effort to learn how to use it. That said, it is fully supported by an almost infinite number of tutorials and downloadable patches. If I correctly understood your description, you might want to look into granular synthesis.
For an idea of what can be done in Max MSP, check out Andrew Spitz's Sound Doodle.
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I agree, check out sound doodle, very cool granular synth. Also maybe for another layer check out the synth called the swarm. It's a replica stand alone instrument based off the swarmatron, which gave the social network it's tone and made you feel on edge. It has a bank of 8 sawtooth oscillators, which the first oscillator is controlled by a base pitch slider and then the span knob controls the relationship of the other oscillators to the first one to give you some really cool tones. It's free on a few sites.
Thanks your thoughts Colin and Sonic. Its for a video clip on language and how words and how there context change. I don't have the timeframe to learn Max but have downloaded Doodle and will have a play with that.