Color comes from the notes actually present in the audio: each detected pitch maps to a hue around a 12-tone color wheel, and note strength sets brightness across the full 0–255 range, so shading is continuous rather than a fixed palette, with an added chance of near-black tones for contrast, more likely in quiet passages. A small mark lands on every detected beat, using both a bass check and a broadband transient check, so it keeps time even before the fuller paint budget opens up; full coverage is still paced to arrive only near the end of the song. Lyric objects appear once, softly, at their first mention. Sensitivity, saturation, contrast, and palette mood below are yours to tune per song.
Off by default, this reproduces exactly what you have now. Switch on for long pieces: the painting fills up within the chosen window, then keeps a slow trickle of new strokes going for whatever time remains, instead of being paced against the full runtime.
A slow swirling turbulence drawn over the growing painting, on its own clock, so the piece stays visibly moving for video even between strokes. Off turns it back into a plain static canvas.