NDI

showstack / protocols / ndi

Also called Network Device Interface, NDI HX.

Vizrt's video-over-IP protocol carrying compressed video, audio and metadata between applications and devices on an ordinary ethernet LAN. It is how graphics machines, capture software, PTZ cameras and switchers move pictures around a venue without pulling SDI.

Video transportProprietary, documentedVizrtVerified

Stewarded by Vizrt (NDI AB), originally NewTek.

Media Large, continuous, on time and in order

Continuous streams that are large enough to be sized properly, and that must arrive in order and on time.

What kills it. Anything that starves the link — usually a management transfer nobody scheduled — and jitter that outruns the receive buffer.

The four flows, and why the model is worth having →

Ports

udp/5353 mDNS discovery
Always used for multicast discovery sending.

tcp/5959 NDI Discovery Server
Optional centralised alternative to mDNS, for when sources must cross subnets.

tcp/5960 Remote source query and enumeration on a machine
NDI 5 and later also use a small number of UDP ports from 5960 up for Reliable UDP.

tcp/5961 Base of the per-stream TCP connections
One port per NDI stream from 5961 upward. Additional ports from 6960 up (multi-TCP or UDP receiving) and 7960 up (multi-TCP, unicast UDP or multicast UDP sending) are used per connection.

Multicast

NDI is unicast by default. Multicast sending is optional and uses ports from 7960 up, and mDNS discovery on 5353 is multicast regardless. Do not enable multicast NDI on a switch without IGMP snooping and a querier.

What it carries

Sample rates: 48 kHz
Audio bit depth: 16-bit, 32-bit
Audio encoding: Floating point or 16-bit PCM, carried with the video
Resolution: Not fixed by the specification
Frame rate: Not fixed by the specification
Colour sampling: 4:2:2, 4:2:0
Video bit depth: 8-bit, 10-bit
Video compression: Visually lossless (NDI High Bandwidth) or H.264/H.265 (NDI HX)

Audio: Audio and video travel together, unlike ST 2110 where they are separate essences.

Video: NDI caps neither resolution nor frame rate; 3840x2160 is where most hardware decoders stop and software goes past it. The two families are very different things sharing one name: High Bandwidth is lightly compressed at 100 to 250 Mbit/s with low latency, HX is long-GOP at a fraction of that and correspondingly more delay.

What goes wrong

Discovery is mDNS, which is link-local. NDI sources do not appear across a router. If you need cross-subnet sources you must run the NDI Discovery Server on TCP 5959 and point every device at it explicitly.

Opening only 5960 and 5961 in a firewall gets you discovery and no video. Each connection also grabs ports from the 6960 and 7960 blocks, so the rule has to cover those ranges.

NDI HX is a different thing to full NDI. It is hardware H.264 or HEVC, much lower bitrate and noticeably more latency, and it is what most cheap PTZ cameras actually send.

Full-bandwidth NDI is roughly 100 Mbit/s for 1080i per stream. A gigabit uplink shared with anything else runs out faster than people expect, and NDI degrades by dropping frames rather than by failing cleanly.

The SDK is royalty-free but proprietary, and the licence requires visible NDI attribution in your application. There is no published wire format, so every implementation goes through Vizrt's binary SDK.

What speaks NDI (40)

40 products — 14 hardware, 26 softwareshow all

Product	Direction	Notes
ArKaos MediaMaster ArKaos	bidirectional	NDI in and out.
CasparCG Server CasparCG project	bidirectional	NDI consumer and producer are both present in the shipped configuration.
Depence Syncronorm GmbH	in	NewTek/Vizrt NDI listed as a supported input on Syncronorm's system-integration page.
grandMA3 onPC MA Lighting	bidirectional
HeavyM HeavyM	bidirectional	Depending on version.
Hippotizer Green Hippo (an ACT Entertainment brand)	bidirectional	NDI can be received on a layer, and each Mix can send an NDI feed at a configurable resolution and framerate, optionally with alpha. Docs warn NDI sending costs real GPU/CPU load above HD.
Isadora TroikaTronix (Mark Coniglio)	bidirectional	Input via the NDI Watcher actor (integrated from Isadora 4, a downloaded add-on actor before that); output is configured in Stage Setup. Syphon (macOS) and Spout (Windows) cover local texture sharing.
L8 L8 LLC	in needs licence	NDI texture input documented on the Unlimited edition.
MadMapper garageCube	bidirectional
Millumin Anomes (Philippe Chaurand)	bidirectional	NDI streams can be used as a layer source, and outputs can be sent as NDI with or without alpha, plus audio.
Mitti Imimot	bidirectional	NDI output and input.
Modul8 GarageCUBE	bidirectional	NDI in and out.
OBS Studio OBS Project	bidirectional	NDI send and receive via the NDI plugin, not in the base install.
openFrameworks openFrameworks community	bidirectional	Through addons.
PIXERA AV Stumpfl	bidirectional	Video over IP.
ProPresenter Renewed Vision	bidirectional	NDI in and out.
ProVideoPlayer (PVP) Renewed Vision	bidirectional	NDI in and out.
Resolume Arena Resolume	bidirectional
Smode Smode Tech	bidirectional	NDI send and receive.
Stage Precision Stage Precision	in	NDI input for camera and video sources.
TouchDesigner Derivative	bidirectional
Unity Unity Technologies	bidirectional	Through vendor plug-ins.
Unreal Engine Epic Games	bidirectional	NDI via plugin.
Ventuz Ventuz Technology	bidirectional	NDI send and receive.
vMix StudioCoast	bidirectional	Core.
WATCHOUT Dataton	in	NDI sources can be used as video inputs.
7thSense Delta Media Server 7thSense	out	NDI output on suitably configured systems.
Analog Way Alta 4K Analog Way	bidirectional	Depending on option.
Analog Way Picturall Mark II Analog Way	in	NDI input.
Avolites Ai Q3 Avolites	bidirectional	Video over IP.
Blackmagic ATEM 4 M/E Constellation HD Blackmagic Design	out	NDI via separate Blackmagic conversion, not native.
Christie Pandoras Box Christie	bidirectional	NDI in and out.
disguise vx 4 disguise	bidirectional	NDI capture and output are part of the Designer feature set.
grandMA3 full-size MA Lighting	bidirectional
Green Hippo Hippotizer Karst+ MK2 Green Hippo	bidirectional	Video over IP.
Hippotizer Boreal+ MK2 Green Hippo	bidirectional	NDI input and output are part of Hippotizer V4.
Megapixel HELIOS LED Processing Platform Megapixel VR	in	Video over IP.
Modulo Kinetic Modulo Pi	bidirectional	NDI input and output.
NETGEAR M4250 (AV Line) NETGEAR	bidirectional	Transported, AV profile available for NDI's bursty streams.
AV Stumpfl PIXERA one AV Stumpfl	bidirectional	NDI send and receive.