Unix Programming - Studying Cases

Case Study: audacity

First, we'll look at an example of transparency in UI design. It is audacity, an open-source editor for sound files that runs on Unix systems, Mac OS X, and Windows. Sources, downloadable binaries, documentation, and screen shots are available at the project site.

This program supports cutting, pasting, and editing of audio samples. It supports multitrack editing and mixing. The UI is superbly simple; the sound waveforms are shown in the audacity window. The image of the waveform can be cut and pasted; operations on that image are directly reflected in the audio sample as soon as they are performed.

Figure6.1.Screen shot of audacity.

Multitrack editing is supported in the simplest possible way; the screen splits into multiple per-track displays in a spatial relationship that conveys their concurrency and makes it easy to match features by inspection. Tracks can be dragged right or left with the mouse to change their relative timing.

Several features of this UI are subtly excellent and worthy of emulation: the large, easily visible and clickable operation buttons with distinguishing colors, the presence of an undo command that removes most of the risk from experimentation, the volume slider that makes softness/loudness visually obvious in its shape.

But these are details. The central virtue of this program is that it has a superbly transparent and natural user interface, one that erects as few barriers between the user and the sound file as possible.