Video Walls Explained: Decoding The Various Tech Approaches
February 25, 2016 by guest author, Hoa Tong
GUEST POST: Tim Griffin, Userful
We all understand the Wow Factor that comes from a beautiful, people-stopping video wall. But few people, even within the digital signage industry, understand what’s going on behind those bright, shiny screens.
Video walls are one of the fastest growing sub-sectors in the world of digital displays, but the technology behind them is often misunderstood, and perhaps, sometimes, even feared.
In this post, I want to help shed some light on the most common approaches to implementing video walls, and help raise the general level of understanding.
There are basically four core technologies on the market today that are driving video walls:
Traditional Video-card based video wall controller
This is the oldest of the technologies. A dedicated computer—basically a specialized PC equipped with extra video cards—is physically attached to the displays, each video output driving one display. These video wall controllers typically come with software and capture cards to connect multiple inputs, configure presets, control outputs and manage the overall configuration.
Traditional video wall controllers are proprietary hardware solutions with a fixed number of inputs and outputs purpose built for video walls. Typically, video wall controllers scale captured input sources, but some video wall solutions allow you to render content directly on the controllers. These are often very expensive, but they offer very high total resolution via the large number of installed graphics card.
Vendors include companies like Barco, and Christie Digital.
Many of the commercial, zero-bezel video-wall displays come with a built-in daisy chain solution that allows the displays to scale a single input source across an entire grid video wall. Tile matrix solutions work best with video walls that don’t require high resolution or advanced features like rotations, multiple simultaneous content streams and preset zones. Obviously, the tile matrix approach you still need a player to generate the HDMI or DisplayPort source.
Vendors include companies like Samsung and LG.
Media-players playing back pre-split content:
Some companies have taken multiple signage player devices and time-synchronized them together to create a video walls playback system. Here, the content must be pre-split, and only the relevant portion of the video uploaded to each of the corresponding individual players—one per display. The players constantly talk to each other or to a server during over the network during playback to maintain synchronization. The key disadvantage of this is the inflexibility and cost of having to prepare the content in advance, and the high software subscription fees
Vendors include Brightsign.
Network-based (AV-over-IP) video wall controller:
This technology marries the power and flexibility of a traditional video wall controller, with the cost, scalability and flexibility advantages inherent with AV-over IP. A central PC renders, captures and splits the content, then sends it out over a standard Ethernet network to the displays.
This offers all the resolution, multi-source and flexibility advantages of a traditional video wall controller. All the content management, splitting and delivery is done in real time, and capture cards and network streaming sources offer a wide range of inputs (like HDMI and SDI). But unlike the traditional controller, it has built-in distribution and almost unlimited scalability (in terms of number of outputs) and artistic flexibility.
Vendors include Userful.
Each technology has its benefits and downsides. For example, traditional video card-based controllers have the ability to output very high resolutions, and spread, as well as divide and subdivide, the display as you want. Unfortunately, these systems are the most expensive, and rely on proprietary hardware. They also must be sized in advance for a specific configuration, limiting opportunities for system expansion.
Tile-matrix scalers provide a low-cost—usually included with high-end commercial displays— solution that is simple to set up. However, future upgrades—for example moving from 4k source content to 6k source content—would require the entire solution to be upgraded.
Pre-splitting the content, then delivering via media players is a great trick if your video wall content rarely changes. However, this can often lock you into a specific content management system at very high subscription costs, and lock you out of real-time content (like social media feeds, weather, news, live TV).
Network based video wall is comparable in cost to tile-matrix or pre-splitting, but offers all the traditional controller. With network-based video walls, the only restrictions on the scalability of the solution are the power of the PC and the capacity of the network, which can be virtually unlimited. Also, these solutions have the flexibility to display and arrange multiple simultaneous real-time content sources, as well as support for multiple video walls running off a single PC.
Network transport enables advanced features like high-availability, as well as built-in cable extension, enabling the PC to be securely locked away.
The key disadvantage is since distribution is over an IP network at gigabit speeds, you need to install at least Cat5e cabling. Additionally, most solutions recommend operation at 30 frames per second to conserve bandwidth (whereas some high end installations require 60fps).
As with any other technology market out there, companies should focus their attention on implementing solutions that are more powerful and flexible, without breaking the bank. Obviously, picking the right core technology is just part of the decision.
Features like easy setup and configuration; and flexibility to support your full range of customer use cases with a single product can be a huge time-saver for system integrators.
Another key consideration is how future-proofed the solution is, and what type of upgrades or expansion would necessitate a complete replacement of the system.