Going behind the scenes with videowalls

The demands being placed on videowalls are greater than ever before, so how do you ensure you have enough processing power being sent to the screen? Steve Montgomery find out.

In simple applications internal image upscaling and screen-to-screen signal passthrough of LCD panels makes the display of a single video feed a simple, almost trivial, job; particularly when the videowall itself is constructed from a square matrix of panels. However in non-square LCD layouts and non-standard LED walls and to achieve more complex, multi-source, multiple window applications, there is a need for offboard video manipulation.  A range of high-performance processors suited to all types of videowall of any practical size has been developed to satisfy this requirement.

These devices are continually evolving to meet new video standards and resolutions and a growing user demand for new and additional features.  Currently, individual LCD displays are increasing in resolution from HD to 4K and this is beginning to affect the videowall market.  “HD is still adequate for most installations, but the trend towards 4K continues,” says Phillip Davenport - EMEA sales manager, Datapath.  “We are receiving a greater number of requests for larger resolutions even beyond 4K. 8K and non-standard resolutions such as 7680x1080 are now much more widespread.  Creative effects are more important with users regularly wanting to create scatter walls, often using multiple screen sizes combined together in a mosaic pattern.  We have no limit on the number of screens we can support. The real limit is often the content and how many pixels can be created.”  

Fadhl Al-Bayaty, videowalls product manager with Matrox Graphics, is in agreement: “HD is still, overwhelmingly, the resolution of choice for the majority of applications.  We are experiencing requests for 4K graphics more frequently.  A full transition to 4K will take time and the mega-resolutions like 8K are still a number of years away from any sort of standard use.”  

The type of application and construction of the wall itself affects the processing system, as Justin Knox, marketing director, RGBlink explains: “In an LCD videowall, each panel is a 2K device and requires an individual video connection.  An LED videowall needs a 2K video connection for up to 2K of pixels.   With the increasingly smaller pitch of LED videowall displays and their equally increasing size, LED videowalls are regularly multi-2K-systems.  In the majority of cases, LED videowalls are not conventional formats and in some cases not even fixed format.”

Datapath - 4K Signage

“In modern, high-end videowall processors, there is a separate video connection for each screen in the wall. In HD applications, this enables each display to show full HD as opposed to having the HD resolution spread across all the displays in the wall.”  says Tom Strade, Black Box VP of technology and innovation.  “The larger the screen, the easier it is to see pixelation and quality degradation with HD video.  However, on larger videowalls, the difference between HD and 4K video is less noticeable and depends on how far away the audience is.  Viewers are usually closer to smaller videowalls, so video quality is more important.”

In the majority of commercial applications, impact and attractiveness of the videowall is an important aspect.  This is often achieved by irregularly shaped displays and rotated displays.  He continues: “The desire to lay out screens in different rotations and angles is definitely present in certain markets.  For instance, advertisers are always looking for new ways to capture viewer attention and arranging videowalls in various shapes, patterns and angles helps accomplish this.  However architectural videowalls present some technical challenges.  The video being sent to the screens has to rotate with the screens; otherwise it will display sideways or upside-down.  Rotating video by 90 or 180 degrees is not too difficult and this technology has been around for a while, enabling the creation of videowalls in many shapes and sizes.  However, the complexity increases for 45 degree or even more specific rotation angles.  Advanced hardware and software is available to do any rotation, enabling videowalls of almost any shape and format to be created.  This technology is more specialised and the price reflects that.”

A further implication on processing capability is the requirement for the best possible image quality in some applications.  Chris Fulton, CEO of Future Software explains: “4K at 60Hz is seen as a key requirement for mission critical command and control areas and medical applications as data display density increases along with the need to reduce eye strain from flickering screens.  The move from HD to 4K has been slow in the retail and pro AV markets, mainly to the cost-versus-benefit equation.  Players are generally software-based and the advantage of 4K is lost due to frame drop and other artefacts.  In the enterprise market 4K, 30Hz is represented in the higher profile installations for both capture and display devices where it is more readily accepted that higher quality comes with a larger ticket price.”

32 panel videowall at the Univeristy of West Scotland with Future Software PIPView Blackbird videowall controller (1)

Manufacturers of videowall processors are actively developing products to support 4K processing on both the input and output sides of the devices.  One of the greatest challenges is in creating a processing system with sufficient bandwidth to process multiple 4K data streams through the system at the same time without loss of quality.  Knox highlights the developments that RGBLink are pursuing: “The VSP628pro II actually supports 4x4 videowalls at 4K, 60Hz with four inputs and four outputs, on any combination of signals including 12G-SDI, DisplayPort and HDMI.  As more display devices emerge with onboard 4K, 60Hz inputs the capability for video processing to deliver this resolution and framerate along with multi-window and multi-layer processing is becoming a reality.”

The capability to handle an ever-greater number of inputs and outputs is also important.  Single chassis designs with 64 inputs and 64 outputs or more are already available.  These can also include additional features like custom resolution output channels and the ability to link several controllers together to produce large video wall arrays.

IP distribution has matured dramatically in recent times and there is now a real demand for source devices to connect to the controller via an IP network and then output to a display device via the same IP network.  Whilst most processors today are hardware-based, this demand is likely to lead to more software-based technology.  Andrew Rothery, Dexon’s business development manager believes that: “Videowall management and control is still very much a hardware-based market with the demand for a physical hardware solution outselling the software-based solutions on the market today. In the coming months and years I think we will see more people introducing software which will use AV over IP technology to send a video stream over the network; with each display receiving a portion of the source signal.  Software-based products do however have their own issues and requirements that need to be adhered to when configuring a system to ensure a good solution.”

Matrox has already built IP capability into their range of high-resolution, high-density Mura products.  These are able to capture, stream and record specific regions of interest and even the entire videowall.  Al-Bayaty outlines the company’s development strategy: “The demand for IP-friendly products is huge. Beyond being IP-capable, videowalls that can talk to the whole universe of connected products are essential because sources and endpoints are moving in the direction of IP. Integrators therefore need to be IP-knowledgeable so they know what is possible, and what is not.  The Mura IPX multiviewer card moves past GPU/OS restrictions, and with it, we are able to put together IP-enabled walls as large as imaginable.  Based on H.264, our Mura IPX videowall controllers handle encoding and recording, as well as a seamless interoperability with all H.264-based products."

Irregular videowall using a Future Software controller on Channel 5's Football League Tonigt show(3)

Videowalls are highly visible display products that are often essential to the operation of a business; as the case for control room displays.  Reliability and continuous operation is paramount.  In critical operations MTBF (mean time between failures) must be long and effective product support from manufacturers is essential in solving and rectifying problems rapidly.

In addition, ease of use and flexibility is an important requirement.  “There is a need to make the control interface for videowalls as user friendly as possible to accommodate many different types of users,” says Strade.  “Some users will pre-configure all their content into layouts that can be switched on demand.  Others want to be able to quickly and easily add, remove, resize and rearrange content on the wall at any time.  These requirements mean constant development in all areas of videowall hardware and software technology beyond just resolution alone.”  

Knox concurs: “Many projects are developed on short timelines and can be quite different at time of installation to the initial plan. Being able to deploy a video processor that is powerful and highly configurable is important to our customers.  We focus on accessibility and ease of use with our all-in-one integrated scaler-mixer products.  We have a common software platform, called XPOSE, across all the videowall processor products which provides integrators with a familiar interface regardless of the processing product they are using.”  

As with all technologies, ongoing customer demands, advances in technology and changing standards will drive the future growth and path of videowall processors.  It is highly likely that IP distribution will play an even more important part as the devices become more deeply and more comprehensively integrated into networks.  We can expect higher resolution processing with even lower image latency and greater colour depth.  In addition, features for specific industries, such as genlocking of outputs for the broadcast market and special effects for creative retail and entertainment are all on their way.