a Pure Data addon for OpenFrameworks
C Pure Data C++
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Copyright (c) Dan Wilcox 2011

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 https://github.com/danomatika/ofxPd for documentation as well as the OF forum post on ofxPd


ofxPd is an Open Frameworks addon for running an instance of the Pure Data audio environment within an OpenFrameworks application. Audio, messages, and MIDI events can be passed to and from pure data patches and the library is thread safe.

Pure Data is a graphical patching environment for audio and multimedia (note: the gui and graphics features are not within the scope of this addon)

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

Build Requirements

To use ofxPd, first you need to download and install Open Frameworks. Development is against the latest version of Open Frameworks on github. Checkout a tag if you need an earlier, stable version.

OF github repository

On Mac OSX, you will need to install Xcode from the Mac Developer Tools.

On Linux, you can use the Makefile and/or Codeblocks project files (without the "_win" suffix).

On Win, you will need Codeblocks+MiniGW and the Win Codeblocks OF package. Use the Codeblocks projects files with the "_win" suffix.


Place ofxPd within a folder in the apps folder of the OF dir tree:


Which version to use?

If you are using a stable version (0062, 007, ...) of OpenFrameworks then you want to use a git tag of ofxPd 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 ofxPd and switch to the OF 0062 tagged version:

git clone git://github.com/danomatika/ofxPd.git
cd ofxPd
git checkout 0062

Using the latest ofxPd

The master branch of ofxPd will work with the current stable version of OpenFrameworks and can be considered relatively stable. The develop branch is used for testing new features and bugfixes before they are applied to master.

If you want to work with the latest unstable (still in development) ofxPd, download the source from the develop branch https://github.com/danomatika/ofxPd/tree/develop or via git clone:

git clone git://github.com/danomatika/ofxPd.git -b develop

Warning: The develop branch will be in flux, so don't be surprised if things do not always work as expected!

Running the Example Project

The example projects are in the example folder.


Xcode3: Open the Xcode project and hit "Build and Run". You might want to choose "Release" instead of "Debug" for faster performance.

Xcode4: Open the Xcode project, select the "ofxPdExample" scheme, and hit "Run".


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

To run it, use the terminal:

cd bin


An example Visual Studio 2010 solution as well as a Codeblocks workspace are included.

How to Create a New ofxPd Project

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

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

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

Then after renaming:


For XCode:

Rename the project in XCode (do not rename the .xcodeproj file in Finder!): XCode Menu->Project->Rename

For Codeblocks (Win & Linux):

Rename the *.cbp and *workspace files to the same name as the project folder. Open the workspace, readd the renamed project file, and remove the old project.

Adding ofxPd to an Existing Project

If you want to add ofxPd to another project, you need to make sure you include the src folder:


You will also need to include some additional C Flags for building the libpd source:

For XCode:

  • create a new group "ofxPd" * drag these directories from ofxpd into this new group: ofxPd/src
  • add a search path to: ../../../addons/ofxPd/src/pd/pure-data/src under Targets->YourApp->Build->Library Search Paths (make sure All Configurations and All Settings are selected)
  • under Targets->YourApp->Build->Other C Flags (make sure All Configurations and All Settings are selected), add
    -DHAVE_UNISTD_H -DUSEAPI_DUMMY -DPD -dynamiclib -ldl -lm

For Linux (Makefiles & Codeblocks):

  • edit addons.make in your project folder and add the following line to the end of the file:
  • edit config.make in your project folder and change the lines for USER_CFLAGS, USER_LDFLAGS and USER_LIBS to:
    USER_LDFLAGS = --export-dynamic
    USER_LIBS = -ldl -lm

For Codeblocks (Win):

  • add the ofxPd sources to the project:
    • right-click on your project in the project tree
    • select "Add Files Recursively ..."
    • navigate and choose the ofxPd/src folder
  • add defines, search paths, and libraries to link:
    • right-click on your project in the project tree
    • select "Build options..."
    • make sure the project name is selected in the tree (not release or debug)
    • select the "Compiler settings" tab, add the following to the "#defines" tab:
    • select the "Search directories" tab, click add the search paths:
    • select the Linker settings" tab, add the following libraries:


Sample Rate

The sample rate is set to 44100 when initializing ofxPd in the examples. If your sample rate is higher, the playback pitch will be higher. Make sure the sample rate is the same as your system audio sample rate to hear the correct pitch.

For example: The default sample rate on Mac OSX is 96000. Running the app at 44100 results in double the playback pitch while initing ofxPd at 96000 gives the correct pitch.

Bugs & Errors

Undefined basic_ostream in XCode

If you get the following linker error in XCode:

Undefined symbols: "std::basic_ostream ...

you need to change the Base SDK to 10.6: Project > Edit Project Settings

RtAudio Hang on Exit in 0062

RtAudio will hang on app exit in OF 0062. The only way to fix this is to make a small edit to the OF 0062 core by editing lib/openFrameworks/sound/ofSoundStream.cpp and commenting line 143 so close() is not called.

"verbose" redefinition in Win Codeblocks

Currently, there is a static function in the videoinput lib on Win that conflicts with a #define in the Pure Data sources. The easy fix, until the OF core is updated, is to comment out line 115 in libs\videoInput\include\videoInput.h.

Note: This change hasn't been tested while using the ofVideoGrabber yet ... there is a slight chance it may cause a crash, be warned.

"undefined reference to SetDllDirectory" in Win Codeblocks

Newer versions of libpd check the windows version, so this needs to be set via a define in your codeblocks project. If you have an old ofxPd project, this is not set, hence the error. See "Adding ofxPd to an Existing Project" above, and add the WINVER=0x502 define to your project.

Adding Pure Data external libraries to ofxPd

ofxPd only includes the standard set of Pure Data objects as found in the "Vanilla" version of PD. If you wish to include an external library from Pd-Extended, etc you need to include the source files in your project and call the library setup function after initializing ofxPd in order to load the lib.

Adding external source files

The source files for externals included with Pd-Extended can be found in the Pure Data Subversion repository on Sourceforge. It is recommended that you use the latest Pd-Extended release branch as it will be more stable then the development version. See http://puredata.info/docs/developer/GettingPdSource

For example, if we want to include the zexy external in our project, we first download the sources files for the latest stable Pd-Extended (0.42 as of this writing) from the Subversion repository (make sure you have svn installed):

svn checkout https://pure-data.svn.sourceforge.net/svnroot/pure-data/branches/pd-extended/0.42

The external sources can be found in the externals folder. For instance, the zexy sources are in externals/zexy/src/. Copy the .h and .c files into your project folder. In my case I create an externals folder in src folder of my project, something like myProject/src/externals/zexy. Then add these files to your ofxPd project.

Note: Some libraries may require external libraries of their own and/or special compile time definitions. Make sure you read the build documentation on the external and include these with your project.

Note: Some special objects included with Pd-Vanilla are not part of the libpd distribution for licensing reasons, mainly expr~, fiddle~, and sigmund~. The sources for these are found with the sources for Pd itself in the pd/extra folder in the Subverison repo.

Calling the external setup function

In order for libpd to use an external library, the library has to register itself on startup. This accomplished by calling the library's setup function which is named after the library followed by a "_setup" suffix: "library_setup()". The zexy setup function is simply "zexy_setup()". Call this setup function after initializing ofxPd in your app's setup() function:

    if(!pd.init(numOutChannels, numInChannels, sampleRate, ticksPerBuffer)) {
        ofLog(OF_LOG_ERROR, "Could not init pd");
    // load libs

If all goes well, you should see some sort of print from the library as it initializes:

[zexy] part of zexy-2.2.3 (compiled: Aug  7 2011)
    Copyright (l) 1999-2008 IOhannes m zmölnig, forum::für::umläute & IEM
[&&~] part of zexy-2.2.3 (compiled: Aug  7 2011)
    Copyright (l) 1999-2008 IOhannes m zmölnig, forum::für::umläute & IEM
[.] part of zexy-2.2.3 (compiled: Aug  7 2011)
    Copyright (l) 1999-2008 IOhannes m zmölnig, forum::für::umläute & IEM

For C++ and some C libraries, this is all your need. The project should compile and the external load fine. However, some pure C libraries are not written with explicit C++ support in mind and, for arcane reasons best not delved into here, the C++ compiler will not be able to find the library's setup function. This is the case with zexy and the compiler error looks like this:

'zexy_setup' was not declared in this scope

In order for the C++ compiler to find the function, we need to add our own declaration. This can be done in your app .cpp file, a project header file, etc. In order to keep things organized, I create an "Externals.h" header file and place it in myProject/src/externals. Here I declare the zexy_setup function using a special syntax:

#pragma once

extern "C" {
    void zexy_setup();

The extern "C" keywords tell the compiler to look for a pure C function, not a C++ function. Make sure to include the "Externals.h" header file where you include "ofxPd.h". Add a setup function declaration for any other externals that need it here.

External library licensing on iOS

Apple's iOS and App Store policies forbid dynamically linking libraries. As such, you cannot include any GPL licensed externals as the GPL expressly requires dynamic linking. Submitting an app using a GPL library is in violation of the GPL and will most likely result in your app being rejected from distribution in the App Store.

GPL patches, however, are not in violation of GPL distribution policies and can be included. They are not compiled into an application binary and can be replaced by the user.

Developing ofxPd

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

Create an account, clone or fork the repo, then request a push/merge.

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