Determining the key of BWV1001 - 1st Movement, Adagio

Let's get weird with Bach: find the key of BWV10001 just by loading and parsing the MIDI file.

https://s3-us-west-2.amazonaws.com/secure.notion-static.com/b5f34163-aa04-4c9a-af5c-ebd68fd25d91/1650fd57388f8c60c592727a076ad22bffc6e534cb3ff2e3c3387da7f2e902560a81750c910d57b76d3328ce1a1158a8b3ddff303558bac8555b09983dd3b992

I’m loading these MIDI files, from a separate server because the Internet Archive doesn't do CORS requests.

We’re looking at BWV1001 - 1st Movement, Adagio, by Johann Sebastian Bach.

Load a MIDI file and convert it using MIDIConvert to get a nice JSON representation. MIDI is both a real-time protocol, a physical connector, and a file format: this is the file format, a format that contains musical information.

Unlike MP3 and its descendents, MIDI stores individual notes and instruments that your computer recreates when it plays the file - it does not store the sound waves. Which is bad for the texture of the music - MIDI files have a characteristic cheesiness - but great for doing quick music analysis.

Chart all the notes. I’ll use vega-lite for this. MIDI has a 'note' representation that’s just a number, because computers store everything as numbers, at the lowest level.

First, combine all notes from all instruments. We don’t particularly care which instrument makes which tone in this case.

Now I want to get a feeling for the key: the notes in this piece, by number of appearances, irregardless of octave, translated from their MIDI numbers into note names.