Create an “audiovisual instrument” that allows a performer to produce tightly coupled sound and visuals. Your software should make possible the creation of both dynamic imagery and noise/sound/music, simultaneously, in real time.
You are challenged to create an open-ended system in which sonic and visual modalities are equally expressive. Its results should be inexhaustible, deeply variable, and contingent on the performer's choices, and the basic principles of its operation should be easy to deduce, yet also allow for sophisticated expression. Interactions with your instrument should generate predictable results.
Assume your instrument receives input from the actions and gestures of a performer. Will they use a keyboard, mouse, multi-touch trackpad, pose tracker, or a less common sensor? Select (or construct) your instrument's physical interface with care, giving consideration to its expressive affordances. Categorize the data streams it provides: are these continuous values, or changes in logical states? Do they have a perceptible duration, and are they persistent or instantaneous? Are they one-, two-, three-, or four-dimensional?
Assume your instrument generates output for a graphic display and audio system. Think through the possibilities offered by different visual variables like hue, saturation, texture, shape, and motion, and different auditory elements including pitch, dynamics, timbre, scales, and rhythm. Link these sonic and visual elements together by establishing mappings between your system's input and output. For example: the faster the performer moves her cursor, the brighter her cursor appears, and the higher the pitch of a synthesized tone. Such mappings help set up expectations that can be manipulated by a performer to create contrast, tension, surprise, and even humor.
Attune us to your instrument's unique expressive qualities by using it in a brief performance. One suggestion for structuring this performance is to begin with an expository demonstration of your instrument's interface, guiding the audience into understanding how it operates before presenting more complex material. The repetition and subsequent elaboration of themes is also a helpful compositional strategy.
Good instruments offer inexhaustible possibilities for expression, composition, and collaboration. To a performer, the value of an instrument hinges on how well it supports the creative feedback loop known as “flow.” i An instrument that is responsive but crunchy can be more gratifying than a device that easily begets dazzling results. Hence, in this assignment, the emphasis is on the suppleness of an instrument's interaction design and the range of expression it makes possible (the performer's experience), rather than on the aesthetics of the audiovisuals it produces.
A “North Star” for instrument design is to create something “instantly knowable, yet infinitely masterable.” ii Consider the pencil, or the piano: its basic principles of operation are simple enough for a child to deduce, yet one can spend a lifetime using it and still find more to say; sophisticated expressions are possible, and mastery is elusive. From the standpoint of systems design, our challenge is that ease of learning and expressive range are antithetical design requirements: optimize for one, and the other suffers. In making an instrument for simultaneous sound and image, this challenge is compounded by another: expressive malleability in one modality often comes at the expense of rigidity in the other.
It is helpful to consider the typology of audiovisual systems and the design strategies they use. Sound visualization, for example, is a common feature in desktop music players, VJ software, and phonology tools. Principles of image sonification underpin film scores, game music, and some tools for the visually impaired. The term “visual music,” used by creators of some color organs and abstract films, can even refer to a strictly silent medium, one comprised solely of animated imagery with temporal structures that are analogous to musical ones. In the realm of computer-based performance systems, designers have used a variety of visual interface metaphors to control and represent sound. “Control panel” interfaces, for example, use knobs, sliders, buttons, and dials to govern synthesis parameters, evoking the look of vintage synthesizers. “Diagrammatic” interfaces, such as scores and timelines, use the graphical conventions of information visualization to organize representations of sound along axes like time and frequency. Others use “audiovisual objects,” wherein a performer stretches, manipulates, or knocks virtual objects together in order to trigger or modulate corresponding sounds. In “painterly interfaces,” gestural marks performed on a 2D surface conjure and influence a fine-grained aural material.