What is NDI?

NDI (Network Device Interface) is a way of sending live video, audio and metadata over a standard Ethernet network. It was created by NewTek and is now part of the Vizrt group. Instead of running a dedicated SDI or HDMI cable between every camera, switcher and recorder, you put each device on the network, and any NDI device can then receive any NDI source. NDI is built for low delay on a local network, which is what separates it from internet streaming protocols such as RTMP.

There are two forms worth telling apart. Full NDI, also called NDI High Bandwidth, uses light compression for a near-lossless picture and is built for local-network production. It needs a lot of network: up to about 150 Mbps for a single 1080p60 stream, so a Gigabit switch carries only a handful at once. NDI HX (HX2 and HX3) compresses the picture much more heavily using H.264 or H.265, so it fits lower-bandwidth links, with some extra processing delay. Choose full NDI where the network has room and picture quality comes first, and NDI HX where bandwidth is tight.

In practice, NDI is widely used in live production to tie cameras, graphics, switchers and recording into one network in place of point-to-point cabling. If a device can send or receive NDI, it can sit anywhere on that network and work with the other NDI devices on it, with no dedicated cable run. Adding a camera position becomes a matter of finding a network socket.