WHAT IS PURE DATA? Pd often is described as an example of a “visual programming language”, a definition that is at least broad enough to avoid inaccuracy. Personally, I define Pd as a graphic patching environment designed for audio production and processing, with extensibility for the addition of other media-related features, such as tools for processing images, text and video. Pd’s graphic patching capabilities consist of a small collection of basic units—objects, messages, numbers, symbols and comments—that
are placed on a canvas-like work area and graphically connected (patched) into signal processing networks (Figure 1), a process similar to constructing a soundproducing arrangement of modules on an old-school modular patching synthesizer. Of course, Pd is a little more modern and a lot more flexible. Its basic units are not predefined synthesis or audio processing primitives. They can be those things (and much more), but you need to define them as such, and you need to know what definitions and values are allowable for each type of unit. Figure 1 illustrates
Figure 1. A Simple Pd Patch WWW.LINUXJOURNAL.COM / MAY 2012 / 81
LJ217-May2012bu.indd 81
4/19/12 3:39 PM