All In On NDI
I am a TriCaster user. I use vMix as well. For my workflows, one thing that would be a lot more expensive and difficult to do without NDI is wireless video. Recently, I was asked to stream a TEDx event. They hired me just a few days before it occurred because it had sold out and a lot more people wanted to see it. The TED organization has published video guidelines on how TED events should look and sound (and everything else as well). These include how many cameras should be used, where they should be, and what the shots should look like. And while the guidelines refer to five or more cameras providing a variety of shots, this event had only two—a front camera and a second camera just to the side of the main one.
There was no back-of-the-room camera showing the whole stage and no camera from behind the presenter to provide a view of audience involvement. The morning of the event, I added a wireless router and two small cameras that provided me with two additional views, with twice as many cameras to cut between for coverage. I ran no wires, and I was able to call both devices up as NDI devices over the wireless network.
In addition, I used a NewTek Connect Spark (Figure 4, below) for capturing the slides. Since it was positioned right next to the audio mixer (and 150 feet from me), I used it to ingest the audio for the event as well. While the Spark is capable of wireless, I ran a wire because I wanted to make sure it couldn’t be interfered with by some rogue wireless system. Wi-Fi has the downside of not being exclusive to the 2.4-GHz or 5-GHz spectrum, and there are other systems that can essentially knock out Wi-Fi when used. A wired connection offers more reliability. My two main cameras were SDI, so the two wireless additional cameras were not essential to the coverage of the event. The essential cameras were connected on wires.
Figure 4. NewTek Connect Spark
Another advantage of an NDI workflow is that it enables you to use a single piece of gear for multiple purposes. For instance, the BirdDog converters (Figure 5, below) are bi-directional. They can be used on a camera to provide video, audio, tally, coms, etc. Or, if needed, you can go into the settings of the device and make it an NDI receiver instead. Then you can have it at the stage receiving the PowerPoint slides for monitors that are at the foot of the stage for presenters to see. Because NDI video is just data, routing any source to any destination on the network is possible.
Figure 5. BirdDog Studio NDI
You can even route a single source to multiple destinations without needing a video distribution amplifier or splitter. It’s just data packets, so there’s no signal loss or interruption if a second, third, or 33rd device listens to those packets or uses them to display the program audio in screens throughout a venue, campus, or event. But then you need to put on your new “networking professional” hat and be aware that the more packets you send around, the more you increase the total amount of data passing through the network and the more bottlenecks can occur depending on the scale of the gear being used. Another case in point: The GM Financial setup uses the three 4K Panasonic camcorders.
The built-in NDI is NDI|HX, which is a lower-bitrate version of NDI. There’s also a full NDI, which is implemented in hardware on converters like those from BirdDog. These full-NDI converters have a much higher bitrate and lower latency, which is important for certain situations, like a live show in which the video will also be displayed on the screens next to the stage, typically called Image Magnification (IMAG). When doing IMAG, you want the least amount of delay from camera to screen, and full NDI delivers this. Imagine you have four 4K cameras using 4K NDI, and then you’re sending a 4K NDI program feed to the screens, all passing over the Ethernet network. A single 4Kp30 stream over NDI could be 280Mbps. A 4Kp60 stream could increase that to 480Mbps—for one camera. Add a second camera, and you’ll have completely saturated the typical gigabit network available in most places. You’ll need a 10-gigabit networking infrastructure, at the least, to handle a 4Kp60 multicam event reliably.
Even HD can offer networking challenges. Consider the campus I mentioned earlier that wanted to deploy NDI everywhere: If it added 12 BirdDog PTZ cameras doing 1080p60 full NDI, that would increase the network load by about 200Mbps per camera. You just added 2.4 gigabits of traffic to what’s likely to be a 1-gigabit network already full of data trying to get through. As I wrote in my 7 Rules for Mobile Multicam Success, Rule #1 is “Bring Your Own Good Wi-Fi.” Essentially, this means your video network needs to be separate from everything else so that it has the bandwidth to pass the traffic with ease. No bottlenecks.
Now, admittedly, if a particular device is not being addressed and “received,” then it’s not actively transmitting the video stream anywhere, and the total bandwidth of all 12 cameras is much lower at any given time. But if two conferences are in session and you have just three cameras in each room—plus one device capturing slides and audio—and they’re all sending video to two mixers, then that’s two rooms of four devices each. With eight devices sending out video at 200Mbps, you’ll be transferring 1.6 gigabits of data that wasn’t there on the network before the program began.
Not every PTZ does that data rate. NewTek’s PTZ camera, for example, outputs 1080p30 video using the lower-bitrate NDI|HX flavor and tops out at 20Mbps. In a huge deployment, that’s a good reason to use lower-bitrate (and longer-latency) NDI|HX devices. Not every camera is going to have the same exact bitrate, as each may encode slightly differently. It’s important to be aware that the type of NDI affects your total bandwidth needs, what your networking hardware can handle, and the caveats of full NDI versus HX.
At present, Microsoft Teams and Skype for Business are the only two videoconferencing apps that support NDI. We have built our remote streaming solutions around Teams. Here's how it works.
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