Software

Facebook invents new unit of time to measure modern attention spans: 1/705,600,000 of a sec

FB VR devs invite you to flick the screen rate

By Thomas Claburn in San Francisco

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Video effects designers who work with C++ code have a new unit of time to work with called a "flick."

Short for "frame-tick" if you're willing to overlook the absence of the letter "l" from either word, a flick lasts 1/705,600,000 of a second.

It's a bit longer than a nanosecond, which clocks in at one billionth (1/1,000,000,000) of a second, and that's by design.

"When working creating visual effects for film, television, and other media, it is common to run simulations or other time-integrating processes which subdivide a single frame of time into a fixed, integer number of subdivisions," explains Christopher Horvath, who spearheaded the creation of the time unit for Facebook's Oculus VR, in the code's GitHub repo. "It is handy to be able to accumulate these subdivisions to create exact 1-frame and 1-second intervals, for a variety of reasons."

It turns out that film and video frame rates can't be evenly divided using nanoseconds.

If you represent the duration of a single frame at 1/24 fps in nanoseconds and then multiply that by 24, the result isn't exactly a billion. And that imprecision can cause problems.

Enter the flick. It can represent single frame durations as integers for various common frame rates including 24Hz, 25Hz, 30Hz, 48Hz, 50Hz, 60Hz, 90Hz, 100Hz, and 120Hz, not to mention their 1/1000 subdivisions.

For instance, one frame at 1/30 fps has a duration of 23,520,000 flicks.

In an email to The Register, a Facebook spokesperson offered as an example a situation where someone is working on a rigid body, fluid, or fracture simulation in a computer graphics environment.

"You can't exactly represent a film frame (1/24) or a VR frame (1/90) as an integer number of nanoseconds," Facebook's spokesperson said. "But, by definition you can represent these based on an integer number of flicks. So, if you are trying to assign some sort of simulation trigger to a specific moment in time (say at 1 second), time synchronization is important."

Without flicks, the losses accumulating through timing mismatches would result in a loss of precision and could throw off the execution of the simulation.

The flick joins a few other obscure time intervals including a jiffy (the definition varies), a shake (10 nanoseconds), and a microcentury (~52 minutes or a millionth of a century, the maximum time for a lecture, attributed to mathematician John von Neumann). ®

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