These are types of music files (not libraries used to load them)
Defined in SDL_mixer.h
typedef enum Mix_MusicType {
MUS_NONE,
MUS_CMD,
MUS_WAV,
MUS_MOD,
MUS_MID,
MUS_OGG,
MUS_MP3,
MUS_MP3_MAD_UNUSED,
MUS_FLAC,
MUS_MODPLUG_UNUSED,
MUS_OPUS,
MUS_WAVPACK,
MUS_GME
} Mix_MusicType;