# 03

Pure Data Workshop

a workshop and performance series by Derek Holzer and Sara Kolster focusing on the interrelation of sound and image.


The workshop component is a three day overview of Pure Data, GEM and PDP, a collection of Free + Open Source Softwares available for Linux and Mac OSX 10.3 which allow image, sound and data to be synthesized and manipulated in the same environment. Participants will learn the basic "grammar" and "vocabulary" of Pure Data, upon which objects for sound, 3D and video will be added. Emphasis will be placed on direct connections between sound and image through three different methods: influence of sound on image, influence of image on sound and the use of common "control data" for both image and sound.

The performance which closes the workshop will demonstrate the various techniques taught. Holzer and Kolster collect together sounds, video, photographic transparencies and found objects from cities they have performed in, and use these elements as the basis for an audiovisual improvisation entitled "resonanCITY".



1) Introduction: Why PD & Why Free + Open Source Software?

Our decision to use Pure Data has been motivated by several factors. First and foremost is the need for a modular environment where audio and video processing is possible without the intrusion of negative elements such as a predetermined Graphical User Environment, cross-platform issues and restrictive licenses. We will discuss these issues, and why it is more important than ever that artists take Free + Open Source Software seriously as tools for creative expression.

2) Installation Clinic

The first part of the workshop will be devoted to installing Pure Data, GEM, PDP and several other externals on the participants' computers. Mac OSX 10.3 and most Linux distributions can be accomodated. While PD and GEM support Windows, PDP and several other externals do not, so Windows users will be encouraged to use a live Linux CD such as Dynebolic during the workshop. (If the venue provides any machines of their own to work on, these will be set up on the previous day.)

3) Pure Data as a Language

Like learning any new language, PD starts with learning vocabulary and grammer. In this case, we will learn the names of many common objects and the syntax of how to use them, in a clear "Geek-to-English" translation which makes the complex data-flow operations of PD understandable to non-technicians and artists.

4) Pure Data for Sound Synthesis

PD has powerful signal-processing abilities, and we will explore these by building a simple, monophonic synthesizer controllable from either a MIDI device or from the keyboard of your computer. Different types of sound sythesis, such as Additive, Subtractive, Amplitude Modulation, Frequency Modulation and Wavetable Synthesis will be covered, along with the use of filters and delays for a variety of effects.


1) Pure Data for Sample Manipulation

Because PD uses a range of very basic building-blocks to store and playback sampled sound, a wide range of manipulations are possible. Here, we will explore pitchshifting, time stretching, looping and basic granular synthesis. Other uses of data stored in tables for control purposes will also be touched on.

2) Pure Data for 3D: GEM

GEM is an external library used in PD for moving 3D graphics under the OpenGL protocol. It is also an ideal environment for VJ mixing. We will explore how to create and manipulate simple 3D objects, how to texture them with images, how to playback and mix video clips in GEM and how to use a live camera input.

3) Pure Data for Physical Modelling: PMPD

PMPD is an external library for PD which allows the creation of physical models, consisting of units of mass and force, which can be used to control both sound and image. We will look at different examples of physical modelling using the sound-processing of PD as well as 3D graphics from GEM to sonify and visualize our "virtual objects".


1) Pure Data for Audio Analysis

We continue our investigation of the audio side of Pure Data by looking at different methods of analyzing sound signals for pitch and amplitude information. The data we extract from the audio can be used to either (re)synthesize new sounds or to control 3D or video graphics manipulations.

2) Pure Data for Video: PDP

PDP (Pure Data Packet) is another external library in PD which is used primarily for video playback and effects filters. We will investigate PDP for direct video synthesis, for the playback and mixing of (audio)visual clips and for the processing of a live camera input. PDP includes several tools for the analysis of video for movement, change and color, which in turn can be used to control sound playback and other events in PD.


1) Workshop Presentation

Public presentation by instructors and workshop participants of tools created during the week, covering the importance of Free + Open Source Software, as well as the practical examples of its use.

2) "resonanCITY" Performance

Many sounds and images in our everyday lives slip past our notice simply because they are too small, or because we lack the proper receivers to pick them up. 'resonanCITY' is an ongoing project to gather these microscopic sounds and images from various cities, and to amplify and transform them. The goal is to build a new city of sound and visuals inside the old one, and to inspire curiosity and exploration of one's own environment.

This audiovisual performance by Sara Kolster and Derek Holzer demonstrates the principles and tools explained during the workshop. Sound and image gathered in various locations around the world, are rendered into a dreamlike journey in a live improvisation.

'resonanCITY' has been performed live in Brasil, Norway, the Baltic States and most recently at the Transmediale 05 in Berlin. 'resonanCITY' also won the Second Prize at the 2005 WRO International Media Art Biennale in Wroclaw, Poland.

by Derek Holzer & Sara Kolster:

May 2005--VisibleSound/AudibleImage Workshop
[BEK, Bergen, NO]

August 2004---VisibleSound/AudibleImage Workshop
[RAM6 Festival, CAC, Vilnius, LT]

August 2004--Visible Sound/Audible Image Workshop
[Daugavpils, LV]

by Derek Holzer:

Feburary 2005--Pure Data Workshop
[College of Santa Fe, Santa Fe New Mexico, USA]

November 2004--PD.Zilla--Open Source AudioVisual Tools Workshop
[Mute Magazine, London, UK]
["Your Machines" @ Centre for Contemporary Arts, Glasgow, UK]
[Waygood Gallery, Newcastle Upon Tyne, UK]

May 2004--RAM05 Open Source AudioVisual Tools Workshop
[RAM5 Workshop, RIXC, Riga, LV]

May 2004--Open Source AudioVisual Tools Workshop
[w/ Frank Barknecht & Jaromil]
[Montevideo/NIM, Amsterdam, NL]

April 2004--Open Source Multimedia Tools Workshop
[Burundi Lab, Bratislava, SK]

March 2004--Pure Data Exposed
[w/ Gerard van Dongen]
[Umatic.nl, Utrecht, NL]

Feburary 2004--Open Source AudioVisual Tools Workshop
[Ecole supérieure de l'image, Poitiers, FR]

December 2003--Open Source AudioVisual Tools Workshop
[w/ Martin Pi]
[CyberPipe, Ljubljana, SI]

October 2003--Open Source AudioVisual Tools Workshop Series
[Monteparadiso Hacklab, Pula, HR]
[Spirit Club, Rijeka, HR]
[MAMA, Zagreb, HR]
[Sarajevo Media Center, Sarajevo, BiH]
[Kuda.org, Novi Sad, YU]

April 2003--Open Source AudioVisual Tools Workshop
[w/ IOhannes Zmoelnig, Thomas Musil, Guenter Geiger & Andrei Savitsky]
[Montevideo/NIM, Amsterdam, NL]



Derek Holzer: derek@umatic.nl
Sara Kolster: sara@umatic.nl


# 03 VisibleSoundAudibleImage
# 02 Pure Data [@ Montevideo]
# 01 Pure Data Exposed!