This is WinampVis, a semi-port of RustampVis as a Winamp-compatible plug-in.
To compile on Linux, you'll need the MinGW version of SDL2 and SDL2_ttf installed (as well as the whole MinGW suite), to compile on Windows, you'll need the SDL2 and SDL2_ttf header files, from SDL2-2.30.0\include (and SDL2_ttf-2.22.0\include), which you rename to "SDL2" (so as to keep the naming scheme in the files consistent) as well as placing the "lib" folder from SDL2 and SDL2_ttf into the root of the project folder.