BlueRiver® Applications Part 3: Video Walls & Multiviewers
10 August 2022 / by Gareth Heywood
In the first two parts of this blog series, we’ve looked at how Semtech’s BlueRiver® platform, the core technology that powers Software Defined Video over Ethernet (SDVoE™), can replace the traditional matrix switch for AV distribution, and with fully integrated USB connectivity, BlueRiver supports more advanced KVM switching applications, typically deployed in control centers and for remote desktop applications. In part three of the BlueRiver applications for Pro AV blog series, we’re going to explore how the powerful integrated image processing engine in the BlueRiver ASIC can enable cost effective video wall and multiviewer applications, removing the need for costly dedicated equipment, while still delivering a high performance, low latency IP-based AV distribution system.
BlueRiver for Video Wall Applications
Video walls can be found pretty much everywhere these days, from shopping malls to airports, and in reception areas of hotels and businesses. A video wall is typically made up of several standard displays, placed together such that a single image is spread across the video wall array, just as I’m showing in the example of a simple two-by-two video wall using four 4K panels below.
Two-by-two Video Wall System Example
The video wall can be sized accordingly by the number of displays, in whatever configuration is required, so there’s no real limitation on the physical size of the video wall. Similarly, the total resolution of the video wall is dependent on the resolution of each panel. Using 4K displays provides a very high-resolution canvas for the applications that demand high quality images. This could be high-value advertising and branding, media and infotainment, or dynamic signage with information to help inform and direct visitors or members of the public.
Inside each of the SDVoE receivers driving each display in the video wall example above, the AV processing engine of the BlueRiver device is being used to crop and scale the source content, in this case, from a remote media server. Each receiver is subscribed to the same source, but only outputting the portion of the image required according to its position in the video wall array. For example, top left, top right, bottom left, and bottom right. Each receiver also ensures that the source content is synchronized across the multiple displays, so there’s no tearing or judder as motion passes across the video wall array.
On top of that, the AV processing engine in each receiver can correct for the bezel or frame around each display. When the displays are butted together, their bezels create a “window frame”, and you want the video to look like it’s behind this frame created by the display bezels. The BlueRiver AV processing includes bezel correction, by entering the physical parameters of the bezel, so there are no artifacts or distortion as objects move across the edges of each display in the video wall, from panel to panel.
Inside the Box
So what’s needed to add video wall functionality to an SDVoE system? Well, it’s actually very simple to implement using the BlueRiver chipset. On the transmitter side, all that’s needed is the low cost BlueRiver AVP1000 for the most basic AV distribution functionality, as shown below.
AVP1000-based SDVoE Transmitter Core Components
However, on the receive-side, we’ve used the BlueRiver AVP2000 which includes the AV processing engine to provide the cropping and scaling functionality required for the video wall application. As shown in the following diagram, we’ve added DDR memory which provides the video frame buffer necessary for synchronizing the video across the video wall array.
AVP2000-based SDVoE Receiver Core Components
With the AVP2000, you also get support for optical connectivity using standard SFP+ optical modules. This is ideal where the video wall is typically remote from the machine room where all the media servers are located, such as with multiple video walls distributed around a campus, many hundreds of meters away from the video source. Pairing the AVP2000 with a multi-mode fiber solution allows for distances between 300m and 400m. Using single mode fiber based SFP+ modules allows for distances in the kilometer range, which is ideal for campus-scale AV distribution.
BlueRiver for Multiviewer Applications
In a multiviewer application, a single display is used to display multiple sources, so only a single SDVoE receiver is required to drive the display, as shown in the diagram below. This receiver can be subscribed to a single source, and then simply through software, be subscribed to multiple sources and configured to display any number of multiview layouts, such as the examples I’m showing on the right side of the diagram: picture in picture, picture by picture, picture and picture, and so on.
Multiviewer System Example and Typical Layouts
This is enabled by the flexibility and scalability of the Ethernet network. Distribution of video content to the receiver doesn’t require a dedicated link per source. A single connection from the network switch to the SDVoE receiver can carry up to 32 sources to be composited together using the BlueRiver AV processor into the desired multiview layout.
In order to conserve network bandwidth, source content is pre-scaled in the SDVoE transmitter, creating what is known as a scaled stream. Each SDVoE transmitter is capable of outputting both the native stream – source connected to the HDMI input – and a scaled stream required by any endpoints configured for multiview, within the constraints of the 10G network bandwidth. SDVoE receivers can still subscribe to the native stream in its original format, to display in full resolution, while SDVoE receivers required for multiview subscribe to the scaled streams. This flexibility not only reduces the number of endpoints and connections to the network switch, but also the need for dedicated and costly multiviewer hardware.
Inside the Box
What does this mean in terms of device selection? For multiviewer applications, we need to upgrade our transmitter to use the AVP2000 with the AV processing engine, enabling the scaling and any frame rate conversion required to generate the scaled stream using the DDR frame buffer. The receiver is the same as we showed above for the video wall application, where the AV processing engine is now used as a powerful video compositor to generate the desired multiview layout.
AVP2000-based SDVoE Transmitter Core Components
With the AVP2000, we can also provide optical connectivity at both the transmitter and receiver. However, designs can also use 10BaseT copper connectivity where shorter distances, up to 100m, is all that’s required. It’s your choice, depending on the applications and size of installs you’re targeting.
Evaluate BlueRiver Technology Today
Comprehensive reference designs supporting both copper and fiber connectivity are available from Semtech, allowing equipment manufacturers and software developers to quickly evaluate the powerful AV processing performance of BlueRiver AV-over-IP technology, and quickly enable advanced video wall and multiviewer applications through software.
In the next installment of the BlueRiver applications blog series, we’ll look at how the low power and small footprint of the BlueRiver ASIC can enable highly integrated solutions, from HDMI wall plates to Smart Display Modules (SDM). You can also learn more about the power and flexibility of BlueRiver solutions for SDVoE in the webinar, “BlueRiver Applications for SDVoE”, and why key Pro AV applications, from matrix switch replacement to full end-point integration require the power and flexibility of SDVoE at the Semtech Pro AV Applications web pages.
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