Software and hardware approaches to creating AV-over-IP solutions for control rooms

How to make an informed choice between software and hardware options for AV solutions in control rooms equipped with video walls.
Just five years ago, AV-over-IP technology was still a novelty in professional video projects. Nowadays, many recognize the benefits of this technology, and the number of projects based on it continues to grow. In many mission-critical control room projects it is common to see video being transmitted from workstations to video walls not through HDMI video cables, but through the network interface.

There are two main architectural approaches to AV-over-IP projects: implementation based on hardware streamers (such as Crestron NVX nodes) or based on software solutions (such as Polywall Streamer). Currently, the hardware approach predominates. This can be explained by the perception of some AV industry professionals who believe that hardware-based AV-over-IP implementations are “more reliable” than software-based ones, which are typically built on Windows operating systems, seen by many as a risk factor.

To be fair, it should be noted that hardware implementations of AV-over-IP are not without their flaws. Equipment can occasionally fail, and the more devices used in a project, the higher the probability of failures and malfunctions. Additionally, hardware technologies lack the flexibility that software solutions offer. Firstly, not all capabilities can be implemented in hardware, and secondly, making changes to hardware solutions and troubleshooting them require significantly more time and resources. It is also important to consider that capturing and encoding streams based on hardware solutions can be much more expensive than software-based approaches.

The software approach to control room management provides maximum flexibility and convenience for users. Furthermore, as new versions and releases become available, customers gain access to the most up-to-date technological capabilities with much lower costs compared to using a hardware approach.
Open source vs commercial
Previously, when professionals mainly had access to free software solutions like OBS (Open Broadcaster Software), it was challenging to build critical environments based on such products. In control rooms business, you need to have fast response in support calls, real helping engineer hand during implementation, someone who can consult and advise. However, currently there are worthy commercial products with high-quality implementations and decent support, which allow critical AV-over-IP infrastructures in control room projects to be equipped with easy-to-implement and flexible software solutions.
PROs and CONs for hardware vs software
From our perspective, the choice between software or hardware options for AV-over-IP in control rooms depends on the specific project requirements and use case scenarios. In some cases, a software implementation may be preferable, while in others, a hardware approach may be more suitable. Capture (Encoding) and Streaming of Image using AV-over-IP.

In hardware solutions, workstations are configured in such a way that the operator's desktop is duplicated on two outputs: one is connected to a monitor (or multiple monitors), and the other is connected to an encoding device (encoder) that captures the signal, converts it into a video stream, and sends it over the local network (streaming). If there are no available video outputs on the workstation (for example, if all existing video outputs are connected to separate monitors), the video cable from the workstation is first connected to a 1-to-2 splitter, which divides the signal into two - the first goes to the monitor, and the second goes to the encoding device. This way, the image not only appears on the screen but also gets transmitted over the network.

In software solutions (as an example, let's consider the mature and proven Polywall Streamer solution that appeared in 2019), the capture and streaming of video signals are performed using the resources of the workstation itself: the processor, graphics card, and network adapter. Unlike hardware encoders, software streamers are not tied to physical video signals, which gives them much more freedom. For example, with a single workstation, multiple video streams can be created, each transmitting the content of one of the monitors or application windows.

In some cases, it is useful to provide the control room operator with remote control of the keyboard and mouse of the workstation or PC whose image is being transmitted to the video wall. Certain models of AV-over-IP hardware solutions (IP-KVM) allow for keyboard and mouse switching, while software solutions of this class use the outdated VNC technology for video transmission, which does not match the concept of "video over the network" in terms of image quality. However, development does not stand still, and within a year or two, similar functionality can be expected from software solutions in the AV-over-IP class.

Hardware solutions also have significant limitations. They work with the signal from a single physical video output, without the ability to "crop" a portion of the image or combine multiple monitors into a single stream. Software technologies do not have such limitations at all - it is possible to capture any part of the desktop or all screens at once. Additionally, it is possible to work with virtual video objects, such as virtual PCs or windows of individual applications, even if they are obscured by other windows.

A similar situation arises with scaling the number of workstations: it is very easy to connect another user, for example, with a laptop, to the video wall if the software approach is followed - just install the software streamer on the laptop. When choosing a hardware approach, additional equipment units will need to be purchased, installed, and configured. For example, in the case of a laptop, an additional hardware streamer, a port for its network connection, and several cables will be required.

Capturing images from cameras connected to the operator's PC using the software approach is done directly on the workstation, without the need for any additional equipment. Additional encoding devices will be required for streaming from cameras using hardware methods. USB cameras need to be first connected to the PC and then one of its video outputs should be connected to the encoding device. HDMI cameras can be directly connected to it. IP cameras equipped with a network port can be connected directly to the network.

It is important to note that user interfaces of hardware solutions are designed to be understood and convenient for system engineers, and end-user operators cannot interfere with the settings and operation of pre-configured hardware solutions. On the other hand, user interfaces of software solutions are designed with end-users in mind, providing them with a wide range of possibilities. Operators can, for example, adjust the quality settings of the transmitted video on-the-fly, such as reducing the video traffic or increasing the resolution and image clarity. In the case of hardware implementations, operators would need to involve a trained AV engineer to make such changes.

The same applies to audio accompaniment: when using software solutions, it can be transmitted along with the video stream or not transmitted at all, and users can change these settings themselves on-the-fly. In hardware-based implementations, the intervention of an AV engineer would be required, and often the selection of other, more expensive end nodes.

Another capability that can be easily achieved using a software approach is disabling the mouse cursor. When displaying images from multiple workstations on a video wall, having multiple cursors on a large screen can confuse control room personnel. Software video solutions allow removing unnecessary cursors. Such an option is not available in hardware solutions.
Some Unique points leaving only one choice
Now let's talk about capabilities that can only be implemented using a software approach to AV-over-IP. Typically, an operator works with multiple applications, and sometimes it is necessary to display them on a shared video wall. A software streamer allows capturing application windows, sending the created video streams over the network, and opening them on the video wall in any configuration, overlaying the newly created streams on the operator's console. For this purpose, the user is provided with a list of running applications from which they can select several (the number of applications that can be selected depends on the solution's features). Similarly, streams from virtual desktop windows can be captured and transmitted.

On the other side, very strong feature of hardware solutions is the absence of additional resource load on workstations and complete independence from the operating systems installed on the workstations. The overwhelming majority of software AV-over-IP solutions, including Polywall, only work in the Windows environment, and each stream occupies a portion of the workstation's resources.
How the AV-over -IP behaves differently in network
Now, let's discuss the transmission of video streams over the network. In the case of a software approach, the process of streaming the video is simplified to selecting the network connection method in the software streamer's user interface. For example, users can choose Wi-Fi or one of the network ports. When using hardware AV-over-IP solutions, the overall scheme is similar: the encoding device sends the captured video stream over the local network (LAN) via a cable through a network adapter, and the option to transmit the stream via Wi-Fi is not provided. Wi-Fi is extremely useful for implementing BYOD (Bring Your Own Device) connections.

Significant differences arise when it is necessary to transmit the video stream beyond the local network through a VPN tunnel, for example, to another office or a remote location. If the stream is generated by hardware devices, significant changes to the settings of network devices would be required to send the stream through a VPN tunnel, and the assistance of network engineers would be needed. When using a software approach, the preparation of the stream for transmission through a VPN tunnel occurs directly on the workstation, without the need to reconfigure network devices.

Another distinguishing feature of software AV-over-IP solutions is that switching to another network adapter or network segment can be done with just a few mouse clicks. If a hardware approach is used, it is not possible to change the network equipment settings on-the-fly. At least, such a capability would be unavailable to regular users or video room operators. To switch the encoding device to another network port or segment, network engineers would need to be involved.
Feeding sources to videowalls is one more important task. And very different
AV-over-IP hardware solutions work with video walls in the following way: each screen of the video wall is connected to a decoder, which retrieves one of the streams from the local network, converts it into a video image, and sends it to the display. In the simplest implementation, individual encoding devices are paired with specific decoders, which display the streams on individual screens or the entire video wall. The operator can choose which workstation is displayed on which screen.

A more advanced implementation is possible with the use of additional video processors, which allow for flexible placement of images. For example, one video stream can be displayed on multiple screens or on a portion of one screen. However, this approach has a significant drawback - additional costs and more complex management of the AV system logic.

In software implementations, the video wall screens are connected to the outputs of the server video controller, which generates the image. Essentially, it receives streaming video from the network, decodes it, and displays it in the desired location on the video wall for the operator.

In the most advanced software options, such as Polywall, the entire video wall is presented to the operator as a single workspace, where various media data, including video streams, are displayed. The operator can place the taken video stream on one screen of the video wall, on multiple screens, in an arbitrary area, or expand it to cover the entire video wall. They can also move the image from one part of the video wall to another, change its size, and more, without any restrictions.

Some vendors, such as Barco, offer both software and hardware options for implementing video walls. However, these solutions are significantly more expensive than hardware solutions with decoders.
Operator consoles are also different
It is worth noting the differences in the management capabilities provided to operators. In hardware implementations, operators usually have only a few presets at their disposal, with the most significant ones used for displaying one stream on the entire screen or different streams on different screens. Software solutions offer a much wider range of functions and modes, as well as the ability to create and update interface parts on the fly, customizing them to current tasks.

One advantage of hardware solutions for working with video walls is the ability to scale the number of screens by cascading decoders. The scalability of software options is limited by the number of video outputs of the control server. In practice, video walls with connected decoders typically do not exceed 25 screens. For comparison, according to NVidia, a video wall with NVidia video cards installed in the control server can cover up to 32 4K screens. This is also approximately the maximum number of screens supported by Windows. However, even this is a significant number, as projects with video walls of such sizes are rare worldwide.
Finally, Key selection criterion
The key question that determines the choice between hardware or software implementation options for video wall projects in C&C is how much flexibility the customer and users in the control room environment require.

If the project simply involves displaying the screens of multiple workstations on the video wall over the network, using one or several pre-defined templates with a custom-programmed control interface, and these settings will not be changed during the whole period of use (3-5 years), then opting for a hardware solution would be quite adequate.

However, as soon as the customer's requirements go beyond these parameters, it is necessary to start considering software solutions. The greater the flexibility required, the more beneficial the architecture of software solutions becomes.

For example, if the sources of video data include software-based elements such as web-based information panels (web dashboards), endpoints of specialized applications like SCADA or GIS, virtual workstations, video conferencing systems, IP cameras and CCTV software endpoints, text messages, documents, etc., only a software video wall controller can create such sources on-demand. If this were to be implemented using hardware technology, it would require adding workstations to the project, housed in server racks, with each serving as a signal source from a separate application. When it comes to the management interface, only software solutions can provide the necessary flexibility and on-the-fly customization for individual users.
Last notice
Lastly, a piece of advice from a group of experts who contributed to this article: just like in any other field of engineering expertise, we recommend keeping abreast of the latest innovations and technological developments so as not to miss the moment when a new technology starts to offer significant advantages over the "classic" approach. In our opinion, something similar has already happened with software-based AV-over-IP solutions used in critical environments. We wish you success in your projects!


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