Mido - MIDI Objects for Python

Warnings

• breaking The `mode` attribute was removed from `key_signature` messages in Mido 1.1.20. Minor keys are now appended with 'm', e.g., 'Cm'.
  Fix: Adjust code referencing `key_signature.mode` to parse the `key_signature.key` string directly.
• breaking Message comparison (`==`) in Mido 1.1.18 started including the `time` attribute. This might break existing comparisons if time was not previously considered relevant.
  Fix: If `time` should be ignored for comparison, compare `msg1.bytes() == msg2.bytes()` instead of `msg1 == msg2`.
• breaking The `pending()` method was removed from the port API in Mido 1.1.10. Instead, `_receive()` is now allowed to return messages.
  Fix: Refactor code using `port.pending()` to use `port.iter_pending()` for non-blocking iteration, or adapt to the new `_receive()` behavior if implementing custom ports.
• gotcha Mido represents MIDI channels as 0-15, while many MIDI specifications and user interfaces use 1-16. Be mindful of this offset when displaying or receiving channel numbers from users.
  Fix: Add or subtract 1 when converting between Mido's internal channel representation and a user-facing 1-16 range.
• gotcha Directly setting attributes on `mido.Message` objects (e.g., `msg.note = 70`) is possible but discouraged. It's generally better to use `msg.copy()` to create a new message with updated attributes for immutability and validation.
  Fix: Use `new_msg = msg.copy(note=70)` instead of `msg.note = 70` to modify messages.
• gotcha As of Mido 1.1.10, `RtMidi` became the default backend, replacing `PortMidi`. While generally an improvement, this might lead to different port availability or behavior for users who relied on `PortMidi`'s default selection.
  Fix: To explicitly use `PortMidi`, set the environment variable `MIDO_BACKEND=mido.backends.portmidi` or call `mido.set_backend('mido.backends.portmidi')` in your program.

Install

• pip install mido Basic installation
• pip install mido[ports-rtmidi] With default RtMidi backend

Imports

• Message

  from mido import Message

• open_input

  import mido; inport = mido.open_input()

• open_output

  import mido; outport = mido.open_output()

• MidiFile

  from mido import MidiFile

Quickstart

This quickstart demonstrates how to create MIDI messages, list available ports, send a message to an output port, and read/play messages from a MIDI file. It includes a fallback for when no physical MIDI ports are available and creates a dummy MIDI file for demonstration.

import mido

# Create a MIDI message
msg = mido.Message('note_on', note=60, velocity=64, time=0)
print(f"Created message: {msg}")

# List available MIDI ports (example, actual names vary)
print("Available input ports:", mido.get_input_names())
print("Available output ports:", mido.get_output_names())

# Open an output port and send a message (replaces 'Port Name' with an actual port if available)
try:
    outport_name = next(iter(mido.get_output_names()), None)
    if outport_name:
        print(f"Attempting to open output port: {outport_name}")
        with mido.open_output(outport_name) as outport:
            print(f"Sending {msg} to {outport_name}")
            outport.send(msg)
            print("Message sent.")
    else:
        print("No output MIDI ports found to send message.")
except Exception as e:
    print(f"Could not send MIDI message: {e}")

# Read a MIDI file (requires a 'test.mid' file, creating a dummy one)
try:
    mid = mido.MidiFile()
    track = mido.MidiTrack()
    mid.tracks.append(track)
    track.append(mido.Message('note_on', note=60, velocity=100, time=0))
    track.append(mido.Message('note_off', note=60, velocity=100, time=120))
    mid.save('test.mid')
    print("Created dummy 'test.mid'")

    print("Reading messages from 'test.mid':")
    for msg in mido.MidiFile('test.mid').play():
        print(msg)
except Exception as e:
    print(f"Could not read/create MIDI file: {e}")