A simple synthesizer in GDScript for Godot 4.
It exists as a demonstration of how to generate sound in realtime in Godot.
Based on the Godot 3.5 Audio Generator Demo.
Add synth.gd to your scene. Call start() and tweak the synth parameters.
If the dsp cannot keep up and the audio streams stops, you can improve performance by increasing
the buffer_size or buffer_sizes_in_advance values, or decreasing the sample_rate.
Performance is an issue, and the Godot docs also mention that GDScrpit isn't ideal for this type of work. Compiled languages might work better.
Run the demo/gui.tscn scene.