The most advanced open-source music visualizer.
projectM is an open-source project that reimplements the esteemed Winamp Milkdrop by Geiss in a more modern, cross-platform reusable library.
Its purpose in life is to read an audio input and to produce mesmerizing visuals, detecting tempo, and rendering advanced equations into a limitless array of user-contributed visualizations.
The preset files define the visualizations via pixel shaders and Milkdrop-style equations and parameters. Included with projectM are the bltc201, Milkdrop 1 and 2, projectM, tryptonaut and yin collections. You can grab these presets here.