This is Stardew Symphony
What this is is a music expansion API that allows users to add in music packs into Stardew Valley and play them without editing the game's default soundtrack. Music can be player per location and season, with additional options to play specific music depending on the time of day and the weather. More options such as muting the default rain soundtrack exist within the config file. This will not mute the music for in-game events or festivals.
Installing music packs is simple as dragging and dropping a music pack into Stardew Valley/Mods/Stardew_Symphony/Music_Files/
Only music names included into the files located at
Stardew Valley/Mods/Stardew_Symphony/Music_Files/(music_pack_name)/Locations
and
Stardew Valley/Mods/Stardew_Symphony/Music_Files/(music_pack_name)/Seasons
will play according to the name of the file.txt