For more information about the examples, such as how the Python and Mojo files interact with each other, see the Examples Overview

MidiKeyboard

A polyphonic synthesizer controlled via a MIDI keyboard.

This example demonstrates a couple differnt concepts: - How to connect to a MIDI keyboard using the mido library - How to use a MIDI keyboard to send note and control change messages to MMMAudio. - How to use Pseq from mmm_python.Patterns to cycle through voices for polyphonic note allocation. - How to create a thread to handle incoming MIDI messages in the background.

This example is able to run by pressing the "play" button in VSCode or compiling and running the whole file on the command line.

This uses the same MidiSequencer.mojo graph as the MidiSequencer example, but instead of using a sequencer to trigger notes, it uses a MIDI keyboard.

Python Code

import sys
from pathlib import Path

# In order to do this, it needs to add the parent directory to the path
# (the next line here) so that it can find the mmm_src and mmm_utils packages.
# If you want to run it line by line in a REPL, skip this line!
sys.path.insert(0, str(Path(__file__).parent.parent))

if True:
    from mmm_python.MMMAudio import MMMAudio

    # instantiate and load the graph - notice we are using the MidiSequencer graph here (the same as in the MidiSequencer example)
    mmm_audio = MMMAudio(128, graph_name="MidiSequencer", package_name="examples")
    mmm_audio.start_audio()

# this next chunk of code is all about using a midi keyboard to control the synth---------------

import threading
import mido
import time
from mmm_python.python_utils import linexp, linlin, midicps, cpsmidi
from mmm_python.Patterns import Pseq, Pxrand

# find your midi devices
mido.get_input_names()

# open your midi device - you may need to change the device name
in_port = mido.open_input('Oxygen Pro Mini USB MIDI')


voice_seq = Pseq(list(range(8)))

# Create stop event
global stop_event
stop_event = threading.Event()
def start_midi():
    while not stop_event.is_set():
        for msg in in_port.iter_pending():
            if stop_event.is_set():  # Check if we should stop
                return
            if msg.type in ["note_on", "control_change", "pitchwheel"]:
                if msg.type == "note_on":
                    voice = "voice_" + str(voice_seq.next())
                    mmm_audio.send_floats(voice+".note", [midicps(msg.note), msg.velocity / 127.0])  # note freq and velocity scaled 0 to 1
                elif msg.type == "control_change":
                    if msg.control == 34:  # Mod wheel
                        # on the desired cc, scale the value exponentially from 100 to 4000
                        # it is best practice to scale midi cc values in the host, rather than in the audio engine
                        mmm_audio.send_float("filt_freq", linexp(msg.value, 0, 127, 100, 4000))
                elif msg.type == "pitchwheel":
                    mmm_audio.send_float("bend_mul", linlin(msg.pitch, -8192, 8191, 0.9375, 1.0625))
        time.sleep(0.01)
# Start the thread
midi_thread = threading.Thread(target=start_midi, daemon=True)
midi_thread.start()


# To stop the midi thread defined above:
# stop_event.set()

Mojo Code