MIDI Piano visualiser

As used on ostilton's Twitch stream:

Uses the Web MIDI API to visualise keypresses on a connected MIDI piano. Code for subscribing to Web MIDI events is adapted from omi-yusuke's visualiser.

Usage

• Connect your MIDI device before loading index.html;
• In OBS, add your browser as a Window Capture source;
• Add a Chroma Key filter to the new source, type Green, and adjust the similarity until the green surround is keyed out;
• Ensure that keys appear in the OBS overlay when pressed on the piano.