It is a Max/MSP patch, running in a Max runtime instance(free version designed to be uneditable). The full version of Max/MSP is capable of editing the player, or creating a similar one.
Many people use Max/MSP to perform electronic pieces. It's essentially a program that is based around code rather than an easy GUI. Incredibly flexible, but pretty hard to learn.
L
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said
over 13 years ago
Max/MSP has some great tutorials and manual though. I was able to hack my way through it pretty quickly. The tutorials and manual are interactive as well.
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