What are the common criteria you need to consider in designing your videowall?

Videowall controller or processors are available with a wide range of features and capabilities. Many of them relate to system performance, image quality, and reliability, while others can help streamline system design and integration needs targeted at specific vertical market applications. Support for these features will vary by manufacturer and model.

Most of the features and capabilities discussed here are relevant to common video wall system designs. When selecting a video wall controller, it is important to understand more than just which source formats, and how many input and output channels must be supported. Assessing the environment and application for the video wall will help identify the most critical features a video wall controller must support. When comparing between controller, be aware that manufacturer claims of capabilities or performance are often represented by inaccurate or misleading specifications in brochures and on Web pages. Many videowall controller features relate to system performance, image quality, and reliability, while others can help streamline system design and integration needs targeted at specific vertical market applications.

Designing Videowall

Type of display technology
There is a different type of technology to make up a large screen display or video wall. It may consist of several numbers of projectors, LED panel, and ultra-narrow bezel TV put together side by side and on top of each other to become a much larger screen. While normal TV screen can be stacked together, usually you would want to use a specialized TV screen with an Ultra Narrow bezel-to-bezel (screen border).  The narrower the bezel, the better because the border lines will be less obvious but they are more expensive. In addition, since the video wall will be operating in a long duration, a more durable commercial display is preferred to avoid any downtime. Beside LCD TV, the latest laser projector with lifetime over 30,000 hours and brightness over 10,000 ANSI lumens with a proper projector screen is also suitable to be used as a videowall too. Finally, you might be interested in considering the newest LED display which is borderless, higher brightness and longer lifetime. Typically suitable LED display pitch is ranging from P1.2mm to P2.5mm where 16:9 format can be achieved. We carry all the above type of video wall display technology depending on your need and budget allocation.

Dedicated Video Bus
Centralized videowall controllers use a data bus to transport video from their inputs to their outputs. Some systems incorporate a dedicated bus for this purpose, while other systems use a common bus for transferring video as well as other inter-system communication. Use of a dedicated video bus ensures that the transfer of video data is not impeded by other activity, providing more reliable, stutter-free video playback, and ensuring the processor responds to user commands in real-time. Arvia videowall controller, adopt FPGA (Field Programmable Gate hardware graphics parallel processing and digital signal processing (DSP) technology to construct distributed and modularized hardware architecture. Thanks to its implementation of cutting edge, parallel processing hardware systems, Arvia Video Wall Controllers offer an astonishing 10Gbps of bandwidth per slot. Regardless of configuration requirement size, it provides fully real-time DVI/HDMI/RGB/SDI frame rates because of its truly none blocking communication architecture.

Scalability
Some end users will want to add more input or output channels over time. This may be part of a phased installation or an unforeseen upgrade. While some controller is easily expandable, some have a “fixed configuration,” and cannot be changed after leaving the factory. Other videowall controllers are upgradeable but may require on-site support from their manufacturers to make hardware configuration changes. For a distributed videowall processing system, or a centralized videowall controller that accepts sources streamed over a network, potentially up to hundreds of input sources may be supported. Arvia videowall controller supports economical fix input/output matrix switcher controller up to 16 input and 16 outputs while offering scalability and expandability via our VPX series that offer modular videowall system from 3 different chassis models; 8, 16 and 36 slots input and output, where each slot can accommodate 4 inputs/outputs. If cards are damaged or disabled, they can be easily swapped out and a new one inserted in they can be easily swapped out and a new additional one can be inserted in a matter of seconds. When choosing your chassis, be sure to allocate a free slot for future upgrade. 

Number of Videowall displays
In a large command center, there is a possibility that there will be more than 1 large videowall display, yet you want to project the same input sources to these displays interchangeably. Luckily, Arvia controller supports the management of multiple video wall groups (LCD, LED, DLP or projection, etc.) via a single controller. It can be designed to support up to 4 groups of a video wall with different resolution and no limitation groups with the same resolution. You can share the same contents across multiple video wall groups. This mean, by acquiring only 1 unit controller, you can use all inputs sources and push to any 4 video wall displays concurrently, without the need to buy an additional controller, making it more cost-effective and convenient.

Redundancy & Accessibility Features
For video wall controllers used in mission-critical or 24/7 environments, redundant and hot-swappable components are essential. Redundant, hot-swappable power supplies keep controller running during a failure, and facilitate replacement without powering down the unit. Hot-swappable fans can quickly and easily be replaced if necessary. The ability to replace these components, without removing the video wall controller from the rack will minimize downtime. 

Operating System
To build a video wall controller or processor system, some manufacturer employs industrial PC chassis architecture
which operates in a Microsoft Windows operating system. While others such as Arvia Controller operates in an embedded operating system (EOS). As a real-time operating system (RTOS), it is developed uniquely for video wall systems and their applications. As a result, it has several distinct advantages:

  • Faster booting speed (<15 seconds)
  • None of Microsoft OS’s vulnerabilities or third-party software bugs that lead to video wall controller
  • system crashes (blue screen). Due to the Arvia’s OS being a closed system, it experiences none of
  • the risks associated with the installation of third-party applications.
  • No computer viruses
  • No maintenance of computer OS and hard drives

Data Storage
Hard drives are one of the first points of failure for a PC. Videowall controllers with hard drives can become inoperable if a failure occurs. To reduce this risk, some videowall controllers use RAID or removable solid-state storage for their operating systems, rather than a single hard drive. Removable solid state storage virtually eliminates the possibility of a hard drive failure, while adding the benefit of reduced boot time.

Upscaling and Downscaling Quality
Maintaining image quality is crucial for video wall controllers, which often display large images at high resolution, or downsize images into smaller windows or “thumbnails.” Depending on the quality of the image processing, scaling sources up or down from native resolution can compromise image integrity. Poor scaling can produce artifacts, which can make imagery ineffective for applications requiring critical analysis of images. Since image quality frequently must be judged subjectively, the best way to assess scaling performance is to see a video wall controller in operation at a site, or in a demonstration where the system is displaying content similar to what will be presented in the intended application.

Full-Color Depth Processing
Full-color depth processing is required to preserve the quality of the 24-bit video or complex graphics without introducing color banding. Some videowall controllers reduce the color depth of incoming source signals to reduce bandwidth on its video bus. While this helps preserve real-time performance, color reproduction will be compromised. This bit reduction may not be noticeable on simple content such as computer desktops or data screens, but may be noticeable with high-definition video and rendered graphic visualizations.

Flexible Source Placement
A video wall controller’s ability to display source windows varies greatly from manufacturer to manufacturer as well as different models. Some controller allows up to four source windows to be displayed on a single screen, while other controllers allow dozens of windows to be presented per screen. The ability to display the same source in multiple windows or multiple outputs at different sizes can be beneficial for very wide videowalls servicing segmented workgroups in a large room. This capability may not appear to be an obvious requirement when first specifying the processor. The greater the source placement and windowing capabilities of the processor, the more flexibility there will be to create the window layouts that satisfy application requirements. Arvia controller supports up to 4x windows on a single display with arbitrary layering, chance layers to be on the top/bottom, zooming in/out, panning, overlay, stretching and picture in picture, whatever you like it. Furthermore, with our videowall software, you save this arrangement (presets) and later recall. You can save up to 32x presets.

Multiple Output Resolutions
Some videowall controllers can output multiple signal formats simultaneously. This is useful for systems that incorporate displays of various resolutions, such as a video wall comprised of large 1920x1080 projection cubes flanked by 1366x768 flat panels as auxiliary displays. However, controller limited to one output format should feed a signal at the native resolution of the video wall displays. For auxiliary displays, signals from the processor may be upscaled or downscaled to match their native resolutions. A video wall controller’s ability to add colored borders and text to source windows can be a powerful feature in many applications. Colored borders can denote the status of the content in a command and control room, such as green for unclassified data and orange for top-secret data. In a traffic monitoring environment, a red border can help highlight an accident, or colors can be used to indicate traffic levels. Overlay text can be used to provide information about the source, such as the location of a reporter, and the local time. Clocks displaying the time for different regions or time zones can be generated by many controllers, allowing an integrator to streamline system designs by avoiding the need for external clocks or status displays. 

Application Control & Visualization
Videowalls in data-driven environments such as utilities and network centers often require the ability to manage applications presented on the videowall using a keyboard and mouse. This can be accommodated by installing and operating applications directly on some videowall controllers, much like a PC. Other solutions integrate hardware or networked software switching systems to manage keyboard and mouse control directly on the source machines. Videowall software solutions require compliance with operating systems and network security requirements, while hardware solutions require more cabling and control integration. It Arvia Controller software can be installed on Windows 7/10. It is a complete, integrated, and intuitive software solution for the control and management of the video wall controller. It can also be controlled remotely via Ipad. Arvia Controller supports live preview function, help you to operate the software more easily. There is a list of input sources preview, which can be selected and dragged onto the main screen. On the main screen, the preview video keeps playing too. This feature makes creating, previewing, and applying layouts in your video wall appears exactly as you envision, easily.

Preview Output
Some organizations require that a smaller presentation of the videowall be viewed elsewhere in a facility, on one or two screens, or be streamed to another location. This allows other staff to see an overview of the video wall, without requiring use of a large number of display devices. Some controller provides a preview output of the videowall within the control software or automatically generate an output that can be connected to a display. Other controllers allow preview layouts to be programmed and presented on additional outputs. This method requires that the video wall controller supports the presentation of a single input on different displays and different window sizes, a feature not supported by all controller.

User levels authorization
Commonly, there will be more than 1 person that will be responsible for the designing and operation of the video wall. By having multiple user levels authorization, the management can be easily organized. Different users can be assigned to manage different areas of the video wall or different contents.

Low Throughput Latency
All video controller will introduce a degree of throughput latency, resulting in the processed output being slightly delayed when compared to the original input source. The amount of latency will vary from a few milliseconds to several hundred milliseconds, depending on the amount of processing being performed, and how efficiently the processor is executing its tasks. A delay of a few hundred milliseconds may have a negligible impact on the presentation for most videowall applications. However, it can be a concern for installations where the video wall is displaying camera feeds for a live event. A throughput delay greater than 40 to 75 milliseconds will introduce a noticeable loss of synchronization between live or house audio and the camera feeds on the video wall. Delays greater than 100 to 200 milliseconds will be unacceptable for operators using a mouse to work with a computer source presented on the video wall. When calculating throughput latency, one must include any other devices in the signal chain that could introduce delays, such as signal extenders, additional scalers or video controller, and displays.

IP Streaming Support
It's common nowadays to integrated feed from IP sources such as CCTV camera, TV channel and others. Compliance to popular standard is crucial if you plan to integrate these input in the future. Arvia Controller supports :

  • H.264 and RTSP protocol 
  • Compliance with Security Criterion: ONVIF/PSIA/GB. 
  • Compliance with Video Conference Criterion: SIP, H.323
  • Each port can decode 16x 1080P, 32x 720P

HDCP Support
High-bandwidth Digital Content Protection, or HDCP, is an encryption system widely used for content delivered by Blu-ray Disc players, satellite and cable TV receivers, and PCs. To properly display digitally encrypted content, all devices in the signal chain must be HDCP-compliant. The increasing use of digital video sources has made HDCP compliance a growing requirement for video wall controllers.

Accurate Input Detection
Incoming source signals can vary widely in signal format and resolution. Quick, accurate input detection and configuration of input sources is ideal. Slow auto-detection can produce blank windows that are presented for an undesirable length of time when switching between window layouts or input sources. Inaccurate input signal detection can result in images shifted horizontally or vertically, displayed at the wrong aspect ratio, or presented with other visual distortions and artifacts. Manual programming to correct these issues for each input can add weeks of programming that could have otherwise been avoided if quick and accurate input detection was supported. This capability also makes integration of new sources, or temporary sources such as guest laptops, simple and easy.

Custom Input Management
When a video wall controller detects an analog input signal, it typically compares it to a list of known formats and selects the closest match to determine the signal parameters. Another technique is to examine certain elements of the signal, such as sync polarity and line timing, and perform a source capture based on VESA standard CVT - Coordinated Video Timing or GVT Generalized Timing Formula calculations for the signal parameters. Complications can arise if there are non-standard signal formats, or if the sources are altered by upstream signal processing or signal extenders. Both situations can prevent accurate detection of incoming signals. To correct this problem, a video wall controller should allow customization of input signal parameters. This will permit manual adjustment of input source sampling to ensure proper source display. Some controller allows custom source profiles to be created for each input, while others allow the custom profile to be created just once and then shared across inputs, reducing integration time and complexity.

Custom Output Modes
Some videowall controllers allow for customizing the resolution of the outputs. This is useful if the system’s display devices are of a non-standard resolution, or when the display device’s resolution is not included in the processor’s default output mode table.

Mullion Compensation
When projectors and projection cubes are stacked next to each other, there is no appreciable image-to-image gap between the displays. However, flat-panel displays typically have a wide physical bezel around the active picture area. The active picture area stops at the inner edge of the bezel. Therefore, when flat panel displays are stacked together to form a tiled display, there can be significant screen-to-screen gaps across panels. If a video processor does not account for the gap between displays, the result looks unnatural, as objects that span screens appear to “jump” between them. A processor can compensate for this effect by clipping away a small percentage of the image which should physically be positioned behind the bezel. The sidebar details the calculations to determine the horizontal and vertical mullion pixel sizes necessary for proper mullion compensation.

Edge Blending Support
Some videowall displays comprise multiple projectors that overlap with each other to create one large, seamless image on a front or rear projection screen. In these systems, imagery must be duplicated between displays in the overlapped region. Also, brightness, contrast, and special color adjustments must be available in zones to balance brightness and color across the blended and unblended regions. Duplicating the imagery required for edge blending is a feature that may not be available on every processor. Some controller may support zoned brightness and color adjustments, but this capability can also be supported by many projector models. Dedicated video controller is also available that support zoned brightness and color adjustments. Careful evaluation of projector adjustment and video wall controller capabilities are required when designing edge-blended systems.

Remote Control Protocol
Some applications may require a touch panel controller or use of a customized application for videowall control. In these systems, the video wall controller must support Ethernet or RS-232 remote control. The range of control options will vary from manufacturer to manufacturer, so it is important to make certain that all required control capabilities are supported. This topic is covered in detail in videowall controller Control.

3D Support
Visualization or simulation applications may require the presentation of 3D content. Few videowall controllers currently support this feature, since 3D imaging is a specialty application. Additionally, the system’s source devices and displays must be compatible with 3D content and signals. When discussing requirements for 3D with an end user, be sure to point out that there are two different types of 3D presentations, passive and active. Passive 3D requires polarized glasses for viewing. Active 3D requires electronically shuttered glasses that receive timing information from a transmitted synchronization signal.

Conclusion
No single video wall controller offers every feature and capability presented in this guide. When designing a system, focus on fulfilling the most critical features needed for the application. Ensure the video wall controller you select will satisfy the application’s requirements. Where specifications and marketing information is not obvious, insist that the manufacturer’s support staff be able to clearly verify that your requirements will be supported. A video wall controller that was extremely successful on one project may not be the best choice for the next project. To understand further, contact our technical sales department for a free consultation on deploying your next video wall project.