Stella's code is licensed under the GNU General Public License, and can be accessed at https://github.com/dbaylies/Stella. All are free to use, modify, and sell it, as long as it maintains the same license conditions.

Code Structure

The code is well commented and somewhat simply structured. A general breakdown is outlined below.

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• The valve state is continuously read.

• FFT results are continuously analyzed.

  • The frequency peak is determined, though not precisely​

• The valve position and FFT results are combined to determine the note being played.

• Corresponding MIDI data is sent via USB, consisting of:

  • note on signals​

  • note off signals

  • note velocity signals

  • volume signals

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That's about it. There's certainly complexity buried in each segment, and quite a few challenges had to be overcome to generate the code, but it's fundamental principles are simple.