EMATech / python-alsa-midi

Python interface for ALSA MIDI sequencer

python-alsa-midi – Python interface to ALSA MIDI Sequencer

This project provides Python interface to ALSA sequencer API.

Features

• Pythonic API to most of the ALSA sequencer functionality
• Access to ALSA sequencer features not available when using other ('portable') Python MIDI libraries:
  • Precise timestamping of messages sent and received
  • Port connection management, including connection between ports on different clients
  • Access to non-MIDI events, like announcements about new clients, ports and connections
• Python 3.7 – 3.11 compatibility
• Both synchronous (blocking) and asynchronous (asyncio) I/O
• Only Python code, no need to compile a binary module. Requires cffi, though.
• MIDO backend provided

Installation

This package requires ALSA library to be installed (libasound.so.2 – 'libasound2' package on Debian-like systems). On a typical Linux system it is probably already installed for some other audio or MIDI software.

python-alsa-midi package may be installed with pip:

python3 -m pip install alsa-midi

This should normally install a binary wheel compiled on a compatible system or pure-python wheel working without compilation.

If no compatible wheel is found build from source package will be triggered, which will also require ALSA library development files (libasound2-dev).

To force installing from source (and compiling the binary extension) use:

python3 -m pip install --no-binary=alsa-midi alsa-midi

To force installing from source without compiling the extension:

PY_ALSA_MIDI_NO_COMPILE=1 python3 -m pip install --no-binary=alsa-midi alsa-midi

Alternatively one can just add the source directory (as checked out from https://github.com/Jajcus/python-alsa-midi.git) to $PYTHONPATH and use the packages directly, with no compilation.

Usage

Detailed documentation is available at https://python-alsa-midi.readthedocs.io/

Simple example:

import time
from alsa_midi import SequencerClient, READ_PORT, NoteOnEvent, NoteOffEvent

client = SequencerClient("my client")
port = client.create_port("output", caps=READ_PORT)
dest_port = client.list_ports(output=True)[0]
port.connect_to(dest_port)
event1 = NoteOnEvent(note=60, velocity=64, channel=0)
client.event_output(event1)
client.drain_output()
time.sleep(1)
event2 = NoteOffEvent(note=60, channel=0)
client.event_output(event2)
client.drain_output()

Using with MIDO

python-alsa-midi can be used as a MIDO back-end too:

export MIDO_BACKEND=alsa_midi.MIDO_BACKEND
mido/examples/midifiles/play_midi_file.py file.mid