Live MIDI input and output
==========================

*Example script* (scamp): `examples/Tutorial/25_MIDI_in_out.py <https://github.com/MarcTheSpark/scamp/blob/main/examples/Tutorial/25_MIDI_in_out.py>`__

*Download:* :download:`25_MIDI_in_out.py <downloads/tutorial_25_midi_in_out/25_MIDI_in_out.py>`

Demonstration of receiving and sending live midi input to and from a midi keyboard. Every note received by the keyboard is echoed back to the midi device half a second later at 75% volume.

*Topics:* :doc:`Interactivity & visualization › MIDI input <interactivity_visualization>`

.. raw:: html

   <iframe src="https://www.youtube-nocookie.com/embed/yXCvrcxzEs8" style="width:100%;max-width:640px;aspect-ratio:16/9;border:0;display:block;margin:0.6em 0" allowfullscreen></iframe>

.. code-block:: python

   from scamp import *

   s = Session()

   s.print_available_midi_output_devices()

   # This assumes we want the first listed MIDI device.
   # To use a different device, give the number or name that
   # you get from printing available devices above.
   piano = s.new_midi_part("piano", midi_output_device=0,
                           num_channels=15)


   # dictionary mapping keys that are down to the NoteHandles used to manipulate them.
   notes_started = {}


   def start_note(pitch, volume):
       # start the copy-cat note and store the handle to it to end it later
       notes_started[pitch] = piano.start_note(pitch, volume)


   def end_note(pitch):
       # end the copy-cat note (if one has started)
       if pitch in notes_started:
           notes_started[pitch].end()
           del notes_started[pitch]


   def midi_callback(midi_message):
       code, pitch, volume = midi_message
       # note on event in any channel
       if volume > 0 and 144 <= code <= 159:
           # fork a copy-cat note to start a 5th higher at 75% volume after 0.5 seconds
           normalized_volume = (volume / 127)
           s.fork(start_note, args=(pitch + 7, normalized_volume * 0.75), when=Moment.after_time(0.5))
       # note off (or note on with velocity 0) event in any channel
       elif (volume == 0 and 144 <= code <= 159 or 128 <= code <= 143):
           # fork the copy-cat note a 5th higher to end after 0.5 seconds
           s.fork(end_note, args=(pitch + 7, ), when=Moment.after_time(0.5))


   s.register_midi_listener(0, midi_callback)
   s.wait_forever()