I set out to build a script that takes songs, splits out their bass stem, then analyzes the stem using pitch detection to find the notes being played. While it's not possible to know exactly which strings are being played for each note, a good guess can be made and played along to while I get better at playing and figure it out myself :)

The output scrolls along to the time of the song inside a normal browser window, with a crossfade slider to let you hear more of the original mix or more of the bass while you play along (i almost always have it set to 90% bass since im playing a fretless bass and i really need to hear the stem mix with my bass to make sure im playing the right note).

After I started playing with it for a while I realized I accidentally created a DDR / Guitar Hero clone to trick myself into practicing. Hope you have fun with it too!