(maintained) Midi addon for openFrameworks
C++ Objective-C++ Objective-C C Makefile Pure Data Shell
Latest commit 6f8f12b Dec 31, 2016 @danomatika tiny whitespace fixes



Midi input and output addon for openFrameworks

Copyright (c) Dan Wilcox 2011-2013
(original implementation by Chris O'Shea, Arturo Castro, Kyle McDonald)

BSD Simplified License.

For information on usage and redistribution, and for a DISCLAIMER OF ALL WARRANTIES, see the file, "LICENSE.txt," in this distribution.

See Documentation on Github and the OpenFrameworks Forum post.

OpenFrameworks is a cross platform open source toolkit for creative coding in C++.



ofxMidi provides Music Instrument Digital Interface IO capability to an OpenFrameworks app

  • ofxMidiIn: a single midi input port, derive from the ofxMidiListener class to receive messages
  • ofxMidiMessage: a received midi message
  • ofxMidiOut: a single midi output port, includes a stream << interface

This project utilizes RtMidi for Mac, Windows, & Linux and PGMidi on iOS.


To use ofxMidi, first you need to download and install OpenFrameworks. ofxMidi is currently developed against the current stable version of Open Frameworks on github.

To get a copy of the repository you can download the source from http://github.com/danomatika/ofxMidi/zipball/master or, alternatively, you can use git clone:

git clone git://github.com/danomatika/ofxMidi.git

The addon should sit in openFrameworks/addons/ofxMidi/.

Which version to use?

If you are using a stable version (007, ...) of OpenFrameworks then you want to use a git tag of ofxMidi for that version. You can select the tag in the Github "Current Branch" menu or clone and check it out using git.

For example, the following commands will clone ofxMidi and switch to the OF 007 tagged version:

git clone git://github.com/danomatika/ofxMidi.git
cd ofxMidi
git checkout 007

Midi Routing


Checkout a useful app for midi port routing called MIDI Patchbay.


Check out the Alsa utility apps aconnect & aconnectgui as well as the qjackctl gui for midi port routing control.


Windows does not come with a virtual MIDI routing system like Linux (ALSA) and OSX (CoreMIDI).

If you want to connect your ofxMidi app to other software (synths, DAWs, etc) check out loopMIDI. Run the app and create a few virtual ports which you can then connect to within your software.

Running an Example Projects

The example projects are in the ofxMidi/midiInputExample, ofxMidi/midiOutputExample, & ofxMidi/midiExampleIOS folders.

Project files for the examples are not included so you will need to generate the project files for your operating system and development environment using the OF ProjectGenerator which is included with the OpenFrameworks distribution.

To (re)generate project files for an existing project:

  • click the "Import" button in the ProjectGenerator
  • navigate the to base folder for the project ie. "midiInputExample"
  • click the "Update" button

If everything went ok, you should now be able to open the generated project and build/run the example.


Open the Xcode project, select the project scheme, and hit "Run".


Open the Code::Blocks .workspace and hit F9 to build. Optionally, you can build the example with the Makefile.

To built and run it on the terminal:

make run


An example Visual Studio solution as well as a Codeblocks workspace are included.

Creating a New ofxMidi Project

Note: These instructions are for manually creating a new project. You do not need to follow these steps if you use the ProjecGenerator app.

To develop your own project based on ofxMidi, simply copy an example project and rename it. You probably want to put it in your apps folder, for example, after copying:

openFrameworks/addons/ofxPd/midiExampleInput/ => openFrameworks/apps/myApps/midiExampleInput/

It must be 3 levels down in the OpenFrameworks folder structure.

Then rename the folder:



Rename the project in Xcode (do not rename the .xcodeproj file in Finder!):

  • Xcode Menu->Project->Rename

Codeblocks (Win & Linux)

  • rename the *.cbp and *.workspace files
  • open the workspace and readd the renamed project file by dragging it onto the project tree (it will complain about the missing project you renamed)
  • if you renamed the project folder make sure to set the project name to this folder name or C::B will not be able to run the binary:
    • right click on project in the tree (not the workspace)
    • Properties...->Title

Visual Studio

  • rename the *.sln, *.vcxproj, & *.vcxproj.filters files
  • open the solution and delete the old project from the projects tree
  • go to File->Add->Existing Projects/Solutions and select the *.vcxproj file
  • right click on the project in the projects tree and rename it

Adding ofxMidi to an Existing Project

Note: These instructions are for manually adding ofxMidi to a project. You do not need to follow these steps if you use the ProjecGenerator app to regenerate your project files.


  • create a new group "ofxMidi" in the "addons" group
  • drag these directories from ofxMidi into this new group: ofxMidi/src & ofxMidi/libs
    • in the Add dialog: add to your current project target, uncheck "Copy items if needed" & select "Create groups"
    • if building for OSX, remove the src/ios & libs/pgmidi folder references
    • if building for iOS, remove the src/desktop & libs/rtmidi folder references
  • add the CoreMIDI framework to your project
    • click on your project in the sidebar
    • select the Summary tab
    • click the + under Linked Frameworks & Libraries
    • search for and select the CoreMIDI.framework from the list
  • add the following directories to your search path in your project's Project.xconfig file (See the Project.xconfig of the example project.):

Linux Makefiles/CodeBlocks

  • edit addons.make in your project folder and add the following line to the end of the file:

Win Codeblocks & Visual Studio

  • add the ofxMidi sources to the project tree ofxMidi/src ofxMidi/libs/rtmidi
    • Codeblocks: right click on the project in the project tree and select Add Files Recursively...
    • Visual Studio: drag the ofxMidi/src & ofxMidi/libs/rtmidi folder onto the project tree
  • add the following search paths:
  • Codeblocks
    • right click on the project in the project tree and select Build Options...
    • select the project name in the tree, not release or debug
    • Search directories tab->Add
  • Visual Studio
    • right click on the project in the project tree and select Properties
    • set the Configuration to All Configurations
    • Configuration Properties->C/C++->General->Additional Directories


Using static ofxMidi objects on Linux causes seg faults

Avoid creating static ofxMidiIn / ofxMidiOut objects on Linux as the compiler seems to set creation order so they are created before ALSA is ready. This leads to a confirmed seg fault on Ubuntu and probably all other flavors of Linux using ALSA. The midi apis on Windows and OSX do not share this problem.

Instead create a static ofPtr and initialize it later:

// in .h:

class MyClass {


    static ofPtr<ofxMidiOut> s_midiOut;



// in .cpp:

ofPtr<ofxMidiOut> MyClass::s_midiOut;


// initialize somewhere else
void MyClass::setup() {
    if(s_midiOut == NULL) {
        s_midiOut = ofPtr<ofxMidiOut>(new ofxMidiOut("ofxMidi Client"));

ofxMidi classes created in constructors don't seem to work

This is related to the issue above, in that the ofxMidi classes are being created too early in the app startup process and the back end MIDI library is not being set up correctly. The easiest & best solution is to call the ofxMidi class setup code as part of you ofApp's setup() function, whether there directly or within a subclass. This way you have direct control over when things are happening as opposed to within a constructor which may be called at an arbitrarily early point.


You can help develop ofxMidi on GitHub: https://github.com/danomatika/ofxMidi

Create an account, clone or fork the repo, then request a push/merge. Please use the develop branch of updates and pull requests.

If you find any bugs or suggestions please log them to GitHub as well.

Adding a Midi Back End

If you want to add a new midi back end (Android, Jack, etc), you'll need two classes derived from ofxBaseMidiIn & ofxBaseMidiOut.

Place your source files in a new folder named after your platform/library and add new include #ifdef flags to ofxMidiIn.h & ofxMidiIn.cpp.

Last, you'll need to add specific #ifdef flags to the static port info ofxMidiIn/Out functions (listPorts, getPortName, etc).

Updating Midi Libraries

RtMidi & PGMidi can be updated by running the update_rtmidi.sh or update_pgmidi.sh shell scripts in the scripts folder.

For RtMidi, edit the version setting in the script header and run the script to download and place the RtMidi sources into libs/rtmidi.

PGMidi sources are placed in libs/pgmidi.

RtMidi.cpp include

Next, make sure to add the following include to RtMidi.cpp at around line 38 or there will be link errors:

#include "ofxConstants.h"