Tech Page: Movin' and Groovin'

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Photo: Courtesy Sonalog

Music and dance have been inextricably intertwined since the dawn of human history, but these activities have traditionally been performed by different individuals skilled in one or the other art form. In my career as a musician, I''ve provided soundtracks for dancers on numerous occasions, and I''ve always found it to be a satisfying experience. Yet there is also a sense of separation from the dancers'' movements, an uncertainty about exactly how the music will be manifested visually, especially in improvised performances.

Wouldn''t it be interesting if dancers could generate their own music as they move? That''s the idea behind the GypsyMIDI controller from Sonalog, a British company that specializes in motion capture (mocap), in which the motion of live actors is captured and applied to animated characters. This technique has received a lot of attention lately for its extensive use in the movie Avatar.

Inspired by the San Francisco dance scene in the late 1990s, Sonalog started experimenting with its Gypsy Mocap system, which is designed for 3D animation applications. As a company statement says, “We wanted to explore the possibility of orchestrating and composing music for real-time performance through body movements and dance. This was the beginning of the discovery of a diverse multimedia instrument that promises to add new dimensions to live performance for visual artists, DJs, and musicians for years to come.”

GypsyMIDI comprises two main components: a bodysuit mechanism and a software application for Mac OS X or Windows. The hardware straps onto a person''s upper torso and arms (see Fig. 1) and provides six rotational sensors for each arm: wrist up/down, wrist rotation, elbow up/down, elbow side to side, shoulder up/down, and shoulder side to side. Each sensor has an angular resolution of 1 degree and sends independent MIDI messages to a MIDI Out port that connects to the computer''s MIDI interface.

Authored in Cycling ''74 Max/MSP, the software app is called eXo, and it lets you map MIDI messages to control various parameters such as note on/off, continuous controllers, pitch bend, etc. Messages from the sensors can also be used to trigger and crossfade samples, loops, and other events such as lighting changes. Once the parameters have been mapped, you can use GypsyMIDI to control any MIDI program, including Steinberg Cubase, Ableton Live, Apple Logic, Digidesign Pro Tools, and Propellerhead Reason, as well as any VST instrument or effect.

Of course, dancers come in different shapes and sizes, and GypsyMIDI is highly adjustable to fit various body types and heights from 5 feet to 6 feet 4 inches. Sonalog claims that it takes only 2 to 3 minutes to set it up and less than 1 minute to put it on, which is good news if you want to don the device in the middle of a performance. Physically fit dancers should have little problem with the 4.6 pounds it adds to their body weight.

More problematic is the MIDI cable that must be connected between the mechanism and computer, which Sonalog says is limited to 15 feet. Even if it could be much longer, no dancer wants to deal with a cable in which they could easily get tangled up. Fortunately, the solution to this problem is relatively simple: a wireless MIDI system such as M-Audio''s MidAir, CME''s WIDI-X8, Kenton''s MidiStream, or Classic MIDI Works'' MIDIjet Pro.

Although GypsyMIDI might look somewhat ungainly and perhaps a bit Terminator-esque, it opens up entirely new avenues of artistic expression that modern dancers are sure to appreciate. I look forward to seeing and hearing the results of their explorations with this new creative tool.