Playmo-re is an online MIDI music sequencer that takes a collaborative approach at generating sound from notes on a score.
From the main page, users can record themselves singing a note attached to a selfie. It doesn't even have to be in tune, since our backend will auto-tune it and scale it to different pitches so that we can play a big range of melodies.
From the player page, users can load a MIDI file (we serve a list of default MIDI files from the server), and it will be played back using random notes other people uploaded, together with a synced selfie display.
It's so fun, that we spent half the hackathon just playing with it!
The frontend uses HTML5 Media and Web Audio, and the backend uses Python with a custom phase vocoder-based pitch stretcher. We use the aubio library in the backend to compute the sung note and detect when it starts.