cycle-midi

Cycle.js drivers to send and receive notes using Web MIDI.

Drivers

• connectionDriver
• instrumentDriver

connectionDriver

connectionDriver accepts a stream. Whenever that stream dispatches, it tries to connect to the instrument over Web MIDI. It returns a stream that dispatches true when the connection attempt succeeds and false when it fails.

instrumentDriver

instrumentDriver accepts a stream of notes to send to the instrument. It may eventually return a stream of notes played on the instrument, but it doesn't do that yet.

Example

function Background({ messages: message$, instrumentConnection: instrumentAvailability$ }) {
  const connectionRequest$ = message$.filter(
    message => message.type === 'connect_to_instrument'
  );

  const playRandomNote$ = message$.filter(
    message => message.type === 'play_random_note'
  );

  return {
    instrumentConnection: connectionRequest$,
    instrument: playRandomNote$.map(
      () => (
        {
          // the MIDI ID of the note, from 21 for A0 to 108 for C8
          note,

          // number of milliseconds to play a note for
          duration: 150,

          // 1 is very soft; 128 is very hard
          velocity: Math.random() * 128,

          // number of milliseconds since the instrument connection to wait
          // before playing this note
          time: 0,
        }
      )
    ),
    messages: instrumentAvailability$.map(
      isAvailable => (
        {
          type: 'instrument_availability_changed',
          payload: true,
        }
      )
    ),
  }
}

To see an real extension written with these drivers, check out the midicast source code.

Installation

yarn add cycle-midi

Usage

Because the two drivers share a single connection to the instrument, you must instantiate them together with makeInstrumentAndConnectionDriver():

import {
  makeInstrumentAndConnectionDriver,
} from 'cycle-midi';

const {
  instrumentDriver,
  connectionDriver,
} = makeInstrumentAndConnectionDriver();

run(
  Background,
  {
    instrument: instrumentDriver,
    instrumentConnection: connectionDriver,
  }
);

License

Apache 2.0