GhostFrame Tech Proves Powerful for Regional Feeds, Shoots Without Reblocking, and More
Single LED wall can be used to create multiple simultaneous outputs
In recent years, the capabilities of virtual studios, green-screen studios, and LED walls have expanded exponentially, thanks to increasingly powerful graphics engines, better graphics tools, and improved tracking. Such developments are also spurring production personnel to look for new ways to derive as much as possible from those elements, and that is one reason a relatively new production toolkit from GhostFrame is beginning to resonate with U.S. broadcasters, Fox Sports among them.
“It’s a toolkit that enables you to hide video content in an LED wall, which is invisible to the naked eye but visible through a camera,” says Peter Angell, CEO, AGS AG, a GhostFrame partner. “Each frame is sliced into a number of subframes. Those subframes include the frames that are supposed to be visible on each of the feeds as well as other frames that are used to visually delete the frames not relevant to each output.
“We do that by showing the inverse image,” he continues. “The simplest way to explain that is with a green screen. We want you to see the green-screen frame on camera, but then we insert a frame that is magenta, the opposite of green, and they are played back so quickly your eye doesn’t see either green or magenta. Instead, you see gray.”
The trick is in orchestrating the subframes in such a way that the overall light cycle of the frame appears to be one-60th of a second, eliminating flicker or motion disruption.
The end result is a system that allows a single LED wall to be used to create multiple simultaneous outputs. For example, a single presenter can stand in front of an LED wall announcing sports scores, and a single camera and the single LED wall can output feeds that have a different look or branding, making it much easier to embrace a future that is increasingly going to require personalized content. Even the studio audience could have a different experience.
”They could see something completely different from what those watching the broadcast or stream see,” Angell notes. ”A sports studio show could be regionalized or have a different feed for the home and visiting teams.”
GhostFrame’s secret sauce is not hardware but firmware sent to the LED wall (currently, it is compatible with LED walls only from Roe Visual LED Display Solutions) and LED-wall–control systems from Megapixel. The firmware is licensed, either on a yearly basis or for a shorter period.
“We do provide initial support as it can be quite hard to set up,” adds Angell.
At the core, he adds, the system is all about the mathematics of camera frame rates and the refresh rate of the LED wall. The LED wall on show at NAB 2023, for example, refreshes around 14,000 times a second while the camera records at 240 fps.
“If we are using a camera with global shutter,” says Angell, “we can sync the camera to the wall, run it at exactly the same rate, and then carve out the individual frames. If we are running at 240 fps, we can get really clean definition for all the frames because all four of the outputs will be 60 fps.”
Other applications can help reduce the time required for resetting a scene or allow the LED wall or floor to display blocking instructions and even scripts to those in the studio while viewers at home see graphics or video elements (think footsteps visible only to talent so they can know where to walk). Camera tracking patterns can also be hidden, allowing the system to be used in a fully enclosed volumetric studio without the need for physical markers.
“We can put the marker invisibly onto the wall,” Angell explains. “Wherever you point the camera, there are markers and physical points that are integrated with TrackMan. When you add it all up, you can do four things at the same time because the LED wall can have four realities.”
The most interesting aspect of the demo at NAB 2023 involved shooting a daytime and nighttime scene at the same time. Three lighting panels around the small set were set up to light a daylight scene; three others lit a nighttime version. With the light panels controlled via the same controller as the LED panel, the subframes for the day scene were synchronized with the daylight panels, the subframes for the night scene with the nighttime panels. The result was one output that looked as if the subject was in daylight and one where the subject seemed to be outside at dusk.
“This is crucial,” says Angell, “because you can light all your realities simultaneously and don’t need to reblock or reshoot or reset the lighting. That’s a real production benefit because you can do three or four things at once without changing anything.”