To fully understand why NDI exists let's briefly go over problems that have been faced in the past. Whenever we want to get a video signal from one point to another we normally reach for a   cable. Way back in the day we had those VGA cables that sent an analog signal from one device to another. The next evolution was switching from an analog to a digital signal with DVI.

In 2002 a standard was created that was backed by multiple tech companies that would aim to be the go-to standard for video signals called HDMI. As you well know the HDMI standard has been included on almost any device that either sends or receives a video signal. In 2007 Displayport was introduced to replace the outdated VGA and DVI formats.

The first main limitation that we run into when using any of the cables above is that we are limited in how long we can run the cable. While for most people this will never be an issue since our computer is normally near its screen and a dvd player isn't usually far away from the TV. But for us that deal with entertainment venues and larger installations we know that running a cable that is too long won't work. 

In order to run video signals long distances we normally reach for an SDI cable or use an ethernet extender that sends HDMI over an ethernet cable. While these work great over longer distances they still require a single cable run for every video signal. And, if you have lots and lots of video to run you are going to need a lot of cables.

This brings us to NDI! NDI which stands for Network Device Interface is a standard developed by NewTek that enables video devices to transmit high-definition video over an IP gigabit network. And since it runs over an IP network we can do some pretty neat signal routing. All we have to do is set up our local network that connects to all the devices, then we can send video signals to all other devices.

NDI is extremely user friendly as well. All we need to do is plug an NDI compatible device into the network and it will broadcast its existence to all other devices using the mDNS format. On a device that accepts NDI all we need to do is select the correct source from the list. Then everything else that is needed to establish a connection is handled behind the scenes.

NDI also allows the transmission of video signals from various software applications, all without the need for any additional cables. This lends itself to being very useful in complex video workflows where video signals need to be sent through multiple devices for processing and switching.

Another benefit of NDI is that it is resolution independent which means that we can send whatever resolution we want in whatever aspect ratio we want. NDI is widely supported as well with implementations on Windows, Linux, Mac, iOS, Android, and even embedded applications!

There are a couple of things that we need to watch out for however. Sending high-resolution video requires a lot of bandwidth, with NDI you can expect upwards of 100 megabits per second to be needed per source. And since it is easy to keep adding NDI sources on the network, make sure your switching gear is able to handle the combined aggregate of all sources or else you won't have a reliable connection.

Another thing to keep in mind is that NDI requires that your network is stable. It was designed to only work on a wired local network and not over the internet. This is because these have significant latency which will interfere with the NDI transmission. There have however in recent years been improvements that use UDP instead of TCP which mitigates this issue significantly.

I absolutely love NDI and have used it in many projects over the years. One project that I am currently working on uses NDI heavily to connect a multi-scene virtual production using unreal engine. We have to move real time generated video between 3 computers, with multiple compositing and post-processing steps in between. Once we plug in a camera to a capture card the rest of the signal flow is all NDI. 

I personally think that IP networks are the way of the future. As we have seen in lighting DMX is slowly being phased out or overshadowed by other protocols that run over the network. This is ultimately because networking allows for peer-to-peer communication and with network switches the infrastructure is much easier to build out. 

And thankfully NDI is now here to allow us to have a robust solution to video over IP.