I watched the demo video, and couldn't convince myself that the images had anything to do with the accompanying music. Cool animations, but not a "music visualizer."
Almost all of the visualizations are responsive to the bass/mid/treb amplitudes and detected beat, but the problem on the SDL version on macOS is latency, which is unfortunately present in the demo video you are likely referring to.
SDL doesn't currently allow for requesting low-latency audio capture so we're looking at PortAudio instead.
