Time-based media refers to media whose content unfolds over time, such as video and sound. The key point is that video is treated not as a collection of still images, but as a three-dimensional form with a temporal axis, described as a Space-Time Volume or Video Cube. Ordinary video playback is explained as a highly limited sampling process that presents this volume one frame at a time, as cross-sections perpendicular to the time axis.
Time-based media is closely tied to temporal synchronization and simultaneity. For example, a system is described that takes video as input and generates matching sound in real time, including both continuous ambient/background sounds and momentary events, with audio output synchronized to the timing of the visual event. In another passage, altering the temporal reference across different parts of a frame disrupts spatial perception and even affects the conditions under which sound can be perceived as a stable object.
In this usage, time-based media is not simply any medium that involves time, but a form in which temporal slicing, synchronization, continuity, and perceptual reference points are central to the work’s structure.