07.02.2020 | Ausgabe 1-2/2020

LED Screens Invade TV Broadcast Sets

There is a myriad of examples of proAV technology making its way into broadcast television productions, but perhaps the one area where technology meant for advertising signage and corporate video production has penetrated the “broadcast” space most is in the use of LED-centric sets for television shows and live newscasts.
Firstly, while a seemingly endless stream of a live competition television shows continue to attract new and ever larger audiences for broadcasters, producing them live has become so complicated that a second technical director (TD), often called a “screens TD,” is now employed in tandem with the lighting department’s graphics server operator to create the look of these sometimes amazing LED video tile-intensive sets. In fact, many show stages now feature so many LED pixels—literally millions—and highly complex lighting rig configurations that it takes a “screens team” just to manage the actual LED tiles. They operate completely separately from main TV broadcast crew.

The challenge for those producing these types of shows is the risk of introducing signal delay and lip-sync error problems when stacking up layers of effects on a video switcher (which is how lighting effects are pre-programmed and launched during the show). Too many layers add latency, which adversely affects the images displayed on the set screens.
For example, on “American Idol,” veteran TD David Bernstein configured an EVS Dyvi production switcher to pass a 32:9 1080p (3840x1080) signals to the screens technician for the upstage wall of the set. The screens tech passed those two feeds through eight image processors in order to increase the Dyvi’s output signals in order to fit the actual (5632 x 1536) pixel-count of the wall.
The look and feel of these broadcasts are indebted to these captivating LED screens, which are of course a mainstay of corporate presentations, advertising billboards and even sports stadiums. The flexibility to display literally any image in any size, resolution or aspect ratio is another big advantage.

We’re also seeing these screens in news studios, which serve as a flexible backdrop that can be changed to meet the requirements of each individual story. Adding touch-screen interactivity to these screens takes on-air presenting to a whole new level. The challenge here is that broadcast TV studios require LED screens to operate at their lowest brightness to avoid overheating. However, reducing the displays’ brightness even to 5-10 percent could lead to various image distortions, such as poor color reproduction, unsmooth gradient, and horizontal stripes across the image.
This is why low heat output and efficient heat dissipation are much sought-after features of a TV studio LED screen. Thanks to advanced ventilation systems, the best “broadcast-friendly” LED screens feature fanless designs with silent operation.
Another top requirement for a TV studio LED screen is a high refresh rate (or the minimum period necessary to renew image for all brightness levels). A high refresh rate ensures flickering-free operation and smooth color gradient while achieving a life-like picture. The higher a refresh rate is, the better image quality is achieved. A refresh rate of up to 7680 Hz is considered state-of-the-art for the most demanding TV projects.
Lastly, current LED displays are designed to be modular in design do that set designers have more creative flexibility in building video backdrops of any sizes or shape. Curved (concave and convex) video backdrops of non-standard aspect ratios are not uncommon in studio design today because they add a sense of depth to the on-air studio (which in many cases are very small in reality). Not coincidently, these non-standard shapes are fairly standard in the ProAV world.
Taking this technology a step further, the development of narrow pixel pitch (NPP) LED video displays has brought fine pitch video walls into broadcast studios. The tighter pixel spacings create a more detailed and crisp image display. With resolutions of 4K and above, these displays provide photo-realistic backgrounds for more comprehensive storytelling and better viewer retention of the topic at hand. Moreover, this fine pitch technology allows for close proximity viewing without the display’s pixels being visible.
So, while there are many ProAV technologies that now support a wide variety of broadcast productions, LED technology has indeed had the biggest influence on how stories are told on broadcast TV. And as they say, a good picture is better than a thousand words.


 

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