From the Linux Audio development List.

Does PD plan to support Paul Davis's JACK? reply: linux-audio-dev@music.columbia.edu

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Perhaps I should have said "complex". GL, GLU, GLUT and GLE have 321 externally callable functions between them. I hope Ardour, or anything, will have as many callable sonic routines one of these days.

Try:

Miller Puckette's, Pure Data or 'PD' - modular environment and scripting language for audio http://www-crca.ucsd.edu/~msp/software.html has a good list also..

and please note: once we get JACK in place, and PD has support for JACK, you'll be able to use such environments as inserts and/or sends from an Ardour mixer strip.

--p