Large format displays are becoming ubiquitous in broadcast environments. Broadcast studios, especially news and sports programs, have at least one in view at all times. These range from single standalone flat panels to full width, often curving, floor to ceiling video walls. Viewers have come to expect a montage of images of everything from newsmakers and sports personalities to Doppler radar, weather forecasts, stock charts and sports scores. Presentation of vibrant and dynamic content makes for compelling story telling and drives greater audience engagement.
Progressive studio designers recognize the value in making video walls an integral part of the broadcast set. Beijing Television Network is a prime example. Beijing TV, one of China’s most watched and influential broadcasters reaching over 800 million viewers, sought out the most advanced video wall solution for their new media operating centre unveiled in 2014. They selected a Prysm Olympic video wall for their state-of-the-art broadcast studio that measures 12.8 meters wide by 2.25 meters high. Curved at four degrees, it is one of the largest and most immersive displays used in broadcast worldwide. Click here to see a video of the usage.
Broadcasters increasingly compete with the internet for viewers and understand that their challenge is to provide compelling and engaging content in a unique way. Viewing habits have changed with TV watched on a range of devices from HD/UHD TVs to tablets and mobile devices. So too have the sources of programming changed with an increasing shift to online streaming providers. Live broadcast of on-air presenters with interactive video walls offers a unique means for broadcasters to engage their audience. It brings its own set of challenges as well. Large video walls offering dynamic content that changes on the fly must be both highly reliable and easy to use.
There are several factors that affect how a video wall looks and responds within the fast paced environment of a live broadcast studio. In the age of HD, and increasingly UHD, resolution and distribution, broadcasters must understand the technology of the video wall - from content acquisition through the entire chain of editing, compositing, camera capture, distribution and display on the many consumer devices.
Brightness and Uniformity
Critical to any broadcast solution is the ability to calibrate and maintain a uniform image across the entire display surface, particularly when the content is white and static. While this may sound simple, the results for some video walls, especially those made with LCD panels, is a lack of uniform colour between screens. For single panel installations this requires management at a pixel level, but for a larger format video wall made up of several interconnected “tiles” the whole wall needs to be calibrated and colour balanced. Prysm’s Laser Phosphor Display (LPD) technology provides highly flexible white point adjustment and maintains full uniformity across adjoining tiles by continuously monitoring the light output and making real-time adjustments. An added benefit of the laser solution means that full black can be obtained per pixel ensuring the highest possible contrast ratio across the whole display. The Beijing TV broadcast studio required a uniform brightness of a wide 178 degree viewing angle to accommodate all camera angles.
Camera Shutter and Moiré
Another challenge when including a video wall within a broadcast studio is not only how it interacts with the camera technology on the set, but also how it displays the original content itself (e.g. newly created static graphics or a live streamed video). High-end camera manufactures such as Sony and Grass Valley are moving away from legacy CCD sensors to the more flexible and cost-effective CMOS arrays as broadcasters increasingly approve them for use. CMOS captures each frame image differently than CCD and this can have an adverse effect on how images, particularly shots involving fast moving objects or a panning camera are replayed on a video wall. In addition the shutter on the studio camera itself needs to be synced in time with the raster of the display wall to avoid unwanted moiré patterns. Prysm video walls incorporate specific solutions to these challenges with its LPD tiles including a high 360Hz refresh rate that eliminates motion blur in fast moving images.
Video walls are not created equally. Differences from capability, reliability, power usage and HVAC requirements vary by technology and manufacturer. In a future post, I will focus on issues related to selection and installation of large-scale video walls within the broadcast environment including reliability and interactive collaboration capabilities.