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Copyright (c) Dan Wilcox 2011-2020

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 for documentation as well as the OF forum post on ofxPd

This project has been supported by the CMU Frank-Ratchye STUDIO for Creative Inquiry, the DU Emergent Digital Practices Program, and my time at the ZKM | Hertz-Lab.


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 macOS, 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 Windows, Qt Creator/Msys2 are recommended as the libpd sources do not currently build in Visual Studio. However, you can use a libpd.dll built by MinGW in a Visual Studio project. See the "Using ofxPd with Visual Studio" section below.


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


The easiest way to do this is via cloning with git:

cd openframeworks/addons/
git clone git://

Which version to use?

The master branch of ofxPd will work with the current stable version of OpenFrameworks and can be considered relatively stable.

Previous versions are tagged using Semantic Versioning with the updates to newer versions of OpenFrameworks and libpd noted in the changelog, CHANGES.txt. You can select the tag in the Github "Current Branch" menu or clone and check it out using git.

If you want to use ofxPd with a previous version of OpenFrameworks, checkout the corresponding version tag after cloning:

git clone git://
cd ofxPd
git checkout 1.5.3

Running the Example Projects

The example projects are in the pdExample & pdExampleIOS 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. "pdExample"
  • Click the "Update" button

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

Notes for iOS Projects

  • As of iOS 10+, you will need to manually add a NSMicrophoneUsageDescription string to the project's info plist or the app will crash immediately:
    1. Click on the blue project at the top of the Xcode file tree (ie. something like "pdExampleIOS"
    2. Click the "Info" tab in the top/middle
    3. Under "Custom iOS Target Properties", hover over the last key in the list and click the "+" button
    4. Add the following:
    • Key: NSMicrophoneUsageDescription
    • Type: string
    • Value: a description string for the app like, ie. "This app needs to use the microphone for bla bla..."
  • If you use the OF release zips from, you need the iOS zip not the macOS zip
  • Make sure that "iOS (Xcode)" is selected in the PG's "Platforms" box

pdMultiExample & Multiple Instance Support

This special example demonstrates libpd's experimental multiple-instance support, where you can run multiple separate instances of libpd concurrently.

To build and run this example, the following C flags must be set: -DPDINSTANCE & -DPDTHREADS. If these are not set, the example will exit early with an error.

Note: multi-instance support is still experimental. For instance, currently each instance still shares a single set of receiver callbacks.


For Makefile builds, these are set in pdMultiExample/config.make.

Project Generator

For project files which are created with the Project Generator (ie. Xcode), uncomment the line in under the common target, save, then (re)generate the project with the PG.


PitchShifter is a simple example application which uses an OF GUI to control a pitch shifter within a PD patch. Like the basic example, you will have to generate the project files using the ProjectGenerator.

How to Create a New ofxPd Project

Note: These instructions are for manually creating a new project from an existing ofxPd project and it's project files (aka Xcode, C::B, etc). You do not need to follow these steps if you use the ProjecGenerator app in which case you may need to add the C Flags as the PG currently seems to have a problem doing this. See the IDE specific instructions on how to do this.

To develop your own project based on ofxPd, either generate a new project with the ProjectGenerator or generate one of the examples, copy, and rename it. You probably want to put it in your apps folder, for example, after copying:

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

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

Note: These instructions are for manually add ofxPd to an existing project. You do not need to follow these steps if you use the ProjecGenerator app in which case you may need to add the C flags as the PG currently seems to have a problem doing this. See the IDE specific instructions on how to do this.

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:


Note: -DLIBPD_EXTRA is optional if you do not need/use the externals in libpd/pure-data/extra

If you want to build ofxPd with the libpd experimental libpd multi-instance support (ie. for pdMultiExample), add these C flags as well:


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/libs/libpd/pure-data/src under Targets->YourApp->Build->Header Search Paths (make sure "All" is selected)
  • Under Targets->YourApp->Build->Other C Flags (make sure "All" is selected), add
    • Note: Make sure you use Other C Flags! Other C++ Flags will not work since libpd is written in C.

For Linux (Makefiles & Codeblocks):

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

Using ofxPd with Visual Studio

As of 2019, the libpd sources may be building in Visual Studio, although this has not been directly confirmed with OF & ofxPd. (At least no one has told me.) If you mainly use VS, try this first before building the libpd.dll via Msys2/MinGW.

The libpd sources do not currently build with the Visual Studio C compiler. In order to use libpd with ofxPd in a Visual Studio project, you need a libpd.lib and libpd.dll libraries built using MinGW (Minimal GNU for Windows) which provides a Unix command shell and compiler.

You can check if there is a pre-compiled libpd for ofxPd available here:

If so, skip to the "Adding libpd" section, otherwise follow the steps below to set up a build environment and build libpd.

Building libpd with Msys2/MinGW

The steps for 64 bit are basically:

  1. Set up Msys2/MinGW: see
  • Make sure to follow all steps in the Msys2 setup instructions, ie. updating packages after install
  1. Open an Msys2 shell (64 bit)
  2. Build libpd: make
  3. Install libpd to a temp folder: make install prefix=build/libpd

Adding libpd to a Visual Studio project

Replace the libpd source code in ofxPd with the libpd headers and library files:

  1. Delete the ofxPd ofxPd/libs/libpd folder
  2. Copy libpd/build/libpd into ofxPd/libs

To set up a VS project using ofxPd, you need to link to the libpd.lib import library and place the runtime libraries for libpd in your project's bin folder.

Add libpd.lib to link stage of the Visual Studio project:

VS Linker properties

  • Set "x64" target
  • Project -> Properties
  • Make sure Active configuration & platform are set (you will need to do this for both Debug & Release builds)
  • Configuration Properties -> Linker -> Input
  • Additional Dependencies -> click on right hand drop down, choose Edit...
  • Add the path libpd.lib: $(OF_ROOT)\addons\ofxPd\libs\libpd\lib\libpd.lib

Add the runtime libraries to the project's bin folder:

  • libpd/build/libpd/lib/libpd.dll
  • libpd/libs/mingw64/libwinpthread-1.dll

Note: You will need to re-add libpd.lib to the VS link stage whenever you regenerate the project with the OF ProjectGenerator.

VS project layout

For 32 bit:

  • Open an Msys2 shell (32 bit)
  • Build libpd using make
  • Set the "Win32" target in your VS project before setting the libpd.lib path
  • Copy pthread from the "mingw32" folder: libpd/libs/mingw32/libwinpthread-1.dll

Screenshots provided by @moebiussurfing.

Contributing a libpd Build for Windows

If you have successfully built a new version of libpd for Windows, please consider contributing a copy for others to use.

Make a zip file with the following layout from your ofxPd directory:

libs/libpd/include/ <-- libpd headers

Name the zip using the following format: "". For example,

"" is a 64 bit build of libpd 0.12 (pre-release) using Visual Studio 2017.

Create an issue on the ofxPd Github repo about your new build and we can add it to the release builds link.


Audio Interfacing & Debugging Audio Issues

libpd as utilized in ofxPd does not handle any of the audio interfacing itself, but is called via the ofSoundStream system within OpenFrameworks. If you have any issues with the sound interface / audio apis themselves, please log an issue to the OpenFrameworks Github repo.

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 macOS is 96000. Running the app at 44100 results in double the playback pitch while initializing ofxPd at 96000 gives the correct pitch.

Running App in the Background on iOS

If you're using ofxPd to build an audio app on iOS, you probably want the app to keep running while in the background (aka switching between other apps or going to the home screen). You can enable this in Xcode by clicking on the Project in the project tree, selecting the "Capabilities" tab, and turning on the "Background Modes" switch, then checking "Audio, Airplay and Picture in Picture". Next, Set "Application does not run in background" to NO in the "Info" tab.

Disabling Automatic Screen Locking on iOS

You may be building an audio app for iOS that you want to run without the automatic screen locking mechanism closing it. You can disable the screen lock timer by adding the following to your ofApp setup() function:

[[UIApplication sharedApplication] setIdleTimerDisabled:YES];

Bugs & Errors

iOS app crashes immediately with something about "Microphone Description"

As of iOS version 10+, apps need to ask the user in order to use the camera, microphone, or location data. If you run an iOS project that uses microphone input (ie. pdExampleIOS), a text description is required or the app will be terminated by the OS.

Since the OF Project Generator (currently) doesn't know how to automatically add these description strings to the Xcode project, you will need to do it manually every time you (re)generate an iOS project.

See the steps listed in the "Running the Example Projects" section.

Xcode: Expected value in expression dispatch.h

The macOS 10.13 SDK now requires the HAVE_UNISTD_H to define a value. This has been fixed in ofxPd's file. You can either use the OF ProjectGenerator to regenerate the Xcode project or add the following to your project's "Other C++ Flags":


Pitch is off on the iPhone 6S

The iPhone 6S hardware seems to prefer a sample rate of 48000 and calling ofSoundStreamSetup() with 44100 will not change that in versions of OF 0.8.4 and previous. This means ofxPd will be running at 44100 but the audio stream is actually 48000, resulting in a higher pitch coming out of your patches and a lower pitch going in.

The fix is to follow Apple's method of setting the preferred sample rate, then grabbing what the actual sample rate is afterwards. You can then use this real value in ofSoundStreamSetup() and ofxPd::init(). The pdExampleIOS has been updated to show how to do this. Hopefully, this functionality will be added to OF in the future.

File "tr1/memory" not found in Xcode

You just upgraded to macOS 10.9 and Xcode 5 right? The default compiler is now LLVM and you need to rebuild your Xcode project files so OF will build correctly. Use the ProjectGenerator in the OF 0.8.0 download to regenerate the project:

  • Choose the parent folder of your project folder
  • Set the name of the project
  • Add ofxPd as an add-on
  • Hit generate

Also note, currently the PG doesn't seem to set the C Flags correctly, so you might have to add them manually. See "Adding ofxPd to an Existing Project" on how to do this.

Unknown type t_float, etc

The compiler doesn't recognize the internal Pd types because it's missing the C Flags needed to build libpd. See the section for your IDE in "Adding ofxPd to an Existing Project" on how to do this.

Undefined basic_ostream in XCode

If you get the following linker error in XCode:

Undefined symbols: "std::basic_ostream<char, std::char_traits<char> ...

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 Git repositories: Other externals may be found elsewhere, including on GitHub.

For example, if we want to include the zexy external in your project, first download the sources files from the Git repository (make sure you have git installed):

git clone

Once cloned, the zexy sources are in zexy/src/. Copy the .h and .c files into your project folder. In my case I create an externals folder in the src folder of my project, something like myProject/src/externals/zexy. Then add these files to your 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.

Calling the external setup function

In order for ofxPd to use an external library, the library has to register itself on startup. This is 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)) {

// 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:

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.


(maintained) a Pure Data addon for OpenFrameworks using libpd




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