A Python wrapper for the RtMidi C++ library written with Cython.
RtMidi is a set of C++ classes which provides a concise and simple, cross-platform API (Application Programming Interface) for realtime MIDI input/output across Linux (ALSA & JACK), Macintosh OS X (CoreMidi & JACK), and Windows (Multimedia Library & Kernel Streaming) operating systems.
python-rtmidi is a Python binding for RtMidi implemented with Cython and provides a thin wrapper around the RtMidi C++ interface. The API is basically the same as the C++ one but with the naming scheme of classes, methods and parameters adapted to the Python PEP-8 conventions and requirements of the Python package naming structure. python-rtmidi supports Python 2 (tested with Python 2.7) and Python 3 (3.2).
python-rtmidi is currently in alpha-stage, which means is is published in the hope that other developers try it out and help finding bugs, and that its API is not yet finalised. What is there should work but is currently only tested thoroughly under Linux/ALSA and less regulary under Linux/JACK and OS X/CoreMIDI. Windows support is still untested but will be reviewed soon.
Here’s a quick example of how to use python-rtmidi to open the first available MIDI output port and send a middle C note on MIDI channel 10:
import time import rtmidi midiout = rtmidi.MidiOut() available_ports = midiout.get_ports() if available_ports: midiout.open_port(0) else: midiout.open_virtual_port("My virtual output") note_on = [0x99, 60, 112] # channel 10, middle C, velocity 112 note_off = [0x89, 60, 0] midiout.send_message(note_on) time.sleep(0.5) midiout.send_message(note_off) del midiout
More usage examples can be found in the tests directory of the source distribution. API documentation is available by looking at the docstrings in the Cython source code or using tools like pydoc or IPython or by reading the RtMidi documentation.
python-rtmidi is a Python C(++)-extension and therefore a C++ compiler and a build environment as well as some system-dependant libraries are needed. See “Requirements” below for details.
If you have all the dependencies, you should be able to install the package with pip or easy_install:
$ pip install python-rtmidi
or, if you prefer setuptools:
$ easy_install python-rtmidi
This will download the source distribution, compile the extension and install it in your active Python installation. Unless you want to change the Cython source file rtmidi.pyx, there is no need to have Cython installed.
$ mkvirtualenv rtmidi (rtmidi)$ pip install python-rtmidi
From the Source Distribution
Of course, you can also download the source distribution package as a Zip archive or tarball, extract it and install using the common distutils commands, e.g.:
$ wget http://chrisarndt.de/projects/python-rtmidi/download/python-rtmidi-0.1a.tar.gz $ tar xzf python-rtmidi-0.1a.tar.gz $ cd python-rtmidi-0.1a $ python setup.py install
Lastly, you can check out the python-rtmidi source code from the Subversion repository and then install it from your working copy. Since the repository does not include the C++ module source code pre-compiled from the Cython source, you’ll also need to install Cython from its Git repository. Using virtualenv/virtualenvwrapper is strongly recommended in this scenario:
$ mkvirtualenv rtmidi (rtmidi)$ cdvirtualenv (rtmidi)$ git clone https://github.com/cython/cython.git (rtmidi)$ svn co svn://svn.chrisarndt.de/projects/python-rtmidi/trunk python-rtmidi (rtmidi)$ cd cython (rtmidi)$ python setup.py install (rtmidi)$ cd ../python-rtmidi (rtmidi)$ python setup.py install
Naturally, you’ll need a C++ compiler and a build environment. On debian-based Linux systems, installing the build-essential package should get you this, on Mac OS X install the latest Xcode or g++ from MacPorts or homebrew. On Windows you can use MinGW.
Then you’ll need Python development headers and libraries. On Linux, install the python-dev package. If you use the official installers from python.org you should already have these.
Only if you want to change the Cython source file rtmidi.pyx or want to recompile rtmidi.cpp with a newer Cython version, you’ll need to install Cython >= 0.17. Currently this version is only available via the Git respository (see Cython web site) as version 0.17pre. The rtmidi.cpp file in the source distribution was compiled with Cython 0.17pre as of 2012-07-13.
RtMidi (and therefore python-rtmidi) supports several low-level MIDI libraries on different operating systems. Only one of the available options needs to present on the target system, but support for more than one can be compiled in.
- Linux: ALSA, JACK
- OS X: CoreMIDI, JACK
- Windows: MultiMedia (MM), Windows Kernel Streaming
On Linux, to get ALSA support, you must install development files for the libasound library (debian package: libasound.dev). For JACK support, install the libjack development files (libjack-dev or libjack-jackd2-dev).
On OS X, CoreMIDI support comes with installing Xcode. For JACK support, install JACK for OS X from http://www.jackosx.com/ with the full installer.
On Windows, you’ll need winmm.dll for Windows MultiMedia System support and you’ll need to edit the WINLIB_DIR variable in the setup.py file to point to the location of this DLL. Support for compiling python-rtmidi with Windows Kernel Streaming is currently not provided by the setup file. Patches are welcome.
Copyright & License
python-rtmidi was written by Christopher Arndt, 2012.
The author can be reached at email@example.com.
The software is released unter the MIT License:
Copyright (c) 2012 Christopher Arndt
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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