There’s a New Unit of Time Just for Virtual Reality


Sometimes the old standards don’t mesh well with new tech.

Throughout the history of timekeeping, the humble second has had a number of very particular definitions.

In 1956, it was defined as “1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time.” In 1967, it shifted to an atomic standard: “9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.” Todya, perhaps you know it best as “approximately one Mississippi.”

Any of those are plenty good enough for timekeeping in day-to-day life but none are particularly well-suited to the literally split-second math required to precisely coordinate single frames of video in virtual reality where screens can update at a variety of different sub-second speeds. In order to do away with messy, decimal-ridden arithmetic, engineers at Facebook-owned Oculus came up with a new unit of measurement called the “flick” to help clean up the math required to program things for VR.

A flick or “frame tick” is a 1/705600000th of a second, designed so that a second worth of flicks will divide evenly by common screen refresh rates like 24, 25, 30, 48, 50, 60, 90, 100, 120 as well as various fractional versions of those numbers and common audio sampling rates. The result is a very big number, but one that will make the precise math of dealing with single frames at different refresh rates.

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