NDI comes in four versions, and the marketing rarely says which one a camera speaks until you are past the checkout. The difference is compression, and compression buys you bandwidth at the cost of latency and, at the margins, picture.
Here is what each one costs and what it needs.
The table
| Full NDI | NDI|HX | NDI|HX2 | NDI|HX3 | |
|---|---|---|---|---|
| Codec | SpeedHQ, lightly compressed | H.264 | H.264 or H.265 | H.264 or H.265, tuned for low latency |
| 1080p60 bandwidth | ~125 to 150 Mbps | ~8 to 20 Mbps | ~8 to 20 Mbps | ~20 to 40 Mbps |
| 4K bandwidth | ~250 Mbps and up | ~20 to 30 Mbps | ~20 to 30 Mbps | ~40 to 80 Mbps |
| Latency | About one frame | Several frames, often 100 ms plus | Better than HX, still buffered | Close to full NDI |
| CPU to decode | Low | Higher | Higher | Higher |
| Typical use | Studio, wired gigabit, few sources | PTZ cameras, phones, encoders | Most current PTZ cameras | Newer cameras where latency matters |
Figures vary by resolution, frame rate and how much the picture moves. A locked-off wide shot compresses far better than a moving crowd.
What this means for a real network
The number that decides your design is not the camera’s, it is the switch’s. A gigabit link carries 1,000 Mbps in theory and comfortably less in practice.
Full NDI at roughly 140 Mbps per 1080p60 source means about six cameras saturate a gigabit link before you have counted anything else on the network. It is a studio format: wired, switched, on its own VLAN.
NDI|HX or HX2 at roughly 12 Mbps per source means twenty cameras fit in the same link with room to spare. This is why almost every PTZ camera sold for churches and conference rooms speaks HX. It is the version that makes a shared building network viable.
NDI|HX3 sits between them: three to four times the bandwidth of HX2, with latency close to full NDI. Worth it when you are cutting live between cameras pointed at the same person and the delay would show.
How many cameras will my network carry?
Take the usable capacity of the link, call it 70% of a gigabit, so 700 Mbps. Divide by the per-camera bandwidth of your NDI version. Then halve it, because every source is often being received by more than one device (the switcher, a monitoring laptop, a recorder) and each subscription is its own stream on the wire.
That gives roughly: 2 to 3 cameras on full NDI, 20 or more on HX2, 8 to 10 on HX3, on a single gigabit link with nothing else fighting for it.
Three practical rules that matter more than the arithmetic:
- Wire everything. NDI over Wi-Fi works in a demo and fails in a room with a congregation in it.
- Put video on its own VLAN. Sharing a subnet with the office printer is how discovery goes intermittent.
- Watch IGMP snooping. On a managed switch, snooping without a querier configured breaks NDI discovery in ways that look random. Either configure the querier or turn snooping off for that VLAN.
Which version do the ViZion cameras speak?
The ViZion Z2 and ViZion D1 support NDI|HX, which is the version that lets a church run three or four cameras on one existing gigabit run. The ViZion SP8 takes eight NDI sources and does not care which flavour each one is.
Does the version change the picture?
At a sensible bitrate, on a shot that is not moving violently, most viewers cannot tell HX2 from full NDI on a 1080p stream that is then re-encoded by YouTube anyway. Where it shows is in fast motion, in fine detail like text on a screen behind a speaker, and in latency when you cut between two cameras on the same subject.
If your output is a stream, HX2 is almost always the right answer. If your output is a large screen in the room with the live event, latency starts to matter and HX3 or full NDI earns its bandwidth.
Common questions
Can I mix versions on one switcher? Yes. The SP8 takes whatever each source sends.
Does NDI work over Wi-Fi? Technically. Reliably, no. Do not design around it.
Is NDI better than SDI? Different. SDI is deterministic, low latency and needs coax to each camera. NDI shares a network you already have and carries control and tally on the same cable. For a building where new cable runs are expensive, NDI usually wins.
Do I need 10 gigabit? Only for full NDI with many sources. For an HX2 setup, gigabit is plenty.
The three-camera church guide puts this into a working system.