It’s useful to think about live video equipment as a system. There are a number of components in that system that work together to create the resulting video. A video system can be very simple, with only two components connected by one cable. Conversely, a video system can be composed of hundreds of pieces of equipment spread across a continent.
Large video systems can grow to be very complex and very complicated. With different resolutions, refresh rates and standards, modern video systems are not simple. Ultimately though, in video, everything is either an input or an output. Something either creates signal or receives signal, many devices doing both. This article aims to break down how to think about video systems.
Video systems become complex largely out of the need to monitor the signals. If you were to take out the requirement that you need to see the video on a monitor, getting signal around would be quite simple. Your cameras would just connect to the switcher and the switcher would just connect to the recorder. This of course isn’t the case. Many people need to see the cameras, the engineer, the camera operator, the director, the audience and more. This is where things get challenging as you don’t just need to see that single camera signal, you need to see many other video signals in the system.
There must be a balance in designing a system between cost and flexibility. The ideal video system is able to meet the needs of the team producing the content while fitting the constraint of the budget. In order to create quality content, the system needs to be able to get the right signals in front of the production team to equip them to succeed.
A multiview is the industry standard way of monitoring sources. The point of the multiview is to monitor multiple signals at one time on one monitor. Today, many video switchers generate a multiview source from the inputs that route into the switcher.
A multiview wall in a broadcast truck
There are many sources in a video system that you are going to need to monitor to do production. Let’s take a look at a few of them.
These sources addressed above are indeed sources, they originate signals. They are things that are going to be seen by the audience and are incredibly important to have right. It’s equally important, however, that the crew producing the video is able to see these signals. That’s what I mean by saying that the complexity of a video system often lies in the need to monitor the signals within it. In order to produce a broadcast, which is often ends up just being a single video signal, many dozens of video signals need to be seen and monitored.
There are of course other signals that need to be seen and monitored in order to ensure the integrity of the video being produced. Here are a few, but there are far more.
You can see that with all of these sources generating signals that need to go to the right places, management of these signals can become difficult. If one were to try to piece meal a video system together, wiring each device up to each other device, things become difficult very quickly. This is where the role of the video router comes into play.
A video router is a hub that all sources and destinations connect to. A video router is at the core of any video system. Without one, you quickly run into problems with being able to manage the routing of sources to destinations. In essence, a video router can route any source that comes into it to any output that it is connected to.
If we think about a video switcher, the program source for the switcher will need to go to dozens of locations. Multiple monitors, recorders, encoders, scopes, multiviews and more. If we take the program signal out of the switcher and route it as an input into the video router, one now can feed as many destinations as the router has outputs with that one signal.
When thinking about how a video router fits into a video system, we have to think about things in two layers. The first being how things are wired, and the second, the effective path that signals take in the system.
For example, consider the path of a camera signal to a record deck. Effectively, what is happening, without considering the router, is that the signal leaves the camera, enters the video switcher, leaves the video switcher and finally enters the program monitor. The camera signal takes a rather clear path to the program monitor, this is “effectively” what is happening.
The effective path of the video signal, shown in red.
With the video router in the picture, the signal takes a more complex path and in reality, this is what physical connections are in place. First, the signal leaves the camera and enters the router, then leaves the router, then enters the switcher, then leaves the switcher, then enters the router, then leaves the router and finally enters the program monitor.
The actual path of the video signal, shown in red.
This may seem strange, but the router affords us much flexibility. Let’s consider the benefit of running the camera signal into the router first rather than the switcher. The camera signal needs to go a number of places; the shading station, an ISO (isolated) record deck, the switcher, an external multiviewer, and maybe a dedicated monitor. If we were to need to get to those destinations without the router, we would have to use a distribution amplifier (DA) dedicated for that purpose. If we needed to change what was on the dedicated monitor, perhaps, we would have to physically move the cable connected to it.
If we run the camera signal into a router and run an output of the router into that same monitor, we don’t have to change any cabling to change the signal. We simply change what source feeds that router output in the router control software or hardware panel. With a router, we don't have to worry about a number of different DAs in our system for our various sources. We only have to worry about connecting everything to our one router.
So, while the signal takes a more complex path, the fact that the router is the hub of our system means that we can get any source to any destination. If we were to consider now the whole map of our video system, there could be dozens of hundreds of connections and it would be too much to consider all at once. This gives an impression of a very complex system that we may not understand right away. However, if we focus on one path of one signal, it’s quite simple. For instance, if we needed to get program to a monitor, all we need to know is the output of the router that feeds that monitor and the input on the router that program is connected to.
In thinking about managing a router you think about the output first and then the input you want to feed to that output. For instance, if we want to route program to a recorder, we first select the recorder’s output on the router then select the input on the router that program is connected to. It seems backward at first, but all outputs need to have a source, not all sources need to go somewhere.
You may wonder, with the router in the signal path, what do I lose? You really don’t lose anything. You can think of a router as matrix of cables that are electronically routed. Routers don’t do anything to the video that passes through them, they just pass it. They don’t scale, they don’t delay, they don’t affect the image quality. In absolute terms, a router does delay the signal, but not an amount that matters for anything.
Newer video routers have special features like audio routing, internal multiviewers, the ability to alert you if there are problems with the outputs and complex control software that lets you save the state of the router or the partial state of the router.
With a router in our system, we are now able to effectively manage the signals in our system. Many of the routes in the route will never change, and that’s fine. Others, however, will change daily or hourly. The point is though, that our router is the core of our system, enabling us to do most of what we need to do without touching a cable.
All of this concludes with the idea that the system should not limit the production team’s ability to do what they need to do. In thinking about a video system, the core of the system centers around the router. Without a backbone to work off of, limitations are hit quickly.