Network Device Interface: Difference between revisions

Revision as of 21:00, 7 October 2023

Revision as of 13:40, 31 October 2023

Line 7:

{{Use British English|date=October 2022}}

'''Network Device Interface''' ('''NDI''') is a software specification developed by the [[technology company]] [[NewTek]] that enables [[high-definition video]] to be delivered, received, and communicated over a [[computer network]] in a low-latency, high-quality manner. The specification is royalty-free and allows for [[frame accurate]] switching, making it suitable for use in live [[Production control room|production environments]].

==Technology==

NDI is designed to run over [[gigabit Ethernet]]<ref>{{cite web|url=https://www.provideocoalition.com/newtek-announces-ndi-an-open-protocol-for-ip-production-workflow/|title=NewTek announces NDI, an open protocol for IP production workflow by Allan Tépper|first=ProVideo|last=Coalition|date=8 September 2015}}</ref> with the NDI codec.<ref>{{cite web|url=http://support.newtek.com/hc/en-us/articles/218109667-NDI-Encoding-Decoding|title=NDI Encoding/Decoding|website=NewTek Knowledge Base}}</ref> It is expected to deliver [[1080i]] [[High-definition video|HD video]] at [[Variable bitrate|VBR]] data rates typically around 100&nbsp;Mbit/s.<ref>{{cite web|url=https://support.newtek.com/hc/en-us/articles/217662708-NDI-Network-Bandwidth|title=NDI Network Bandwidth|website=NewTek Knowledge Base}}</ref>

By default, NDI uses the [[mDNS]] ([[Bonjour (software)|Bonjour]] / [[Zeroconf]]) discovery mechanism to advertise sources on a local area network, such that NDI receiving devices can automatically discover and offer those sources. It also supports 2 other discovery modes (NDI Access, NDI Discovery Server) that allow for operations across [[subnet]]s and without mDNS. Sources are created using an arbitrarily selected [[Transmission Control Protocol|TCP]] [[Port (computer networking)|port]] from a range of ports on the NDI send host. When a source is requested, a TCP connection is established on the appropriate port with the NDI receiver connecting to the NDI sender. NDI 3.x has options to use [[User Datagram Protocol|UDP]] [[multicast]] or [[unicast]] with [[forward error correction]] (FEC) instead of TCP, and can [[Load balancing (computing)|load balance]] streams across multiple [[network interface controller]]s (NICs) without using [[link aggregation]]. The release of NDI version 4.0 introduces multithe 'Multi-TCP' connectionstransport.

NDI carries video, multichannel [[uncompressed audio]]{{Citation needed|date=September 2020|reason=Please link to an official source verifying this claim}} and [[metadata]]. Metadata messages can be sent in both directions allowing the sender and receiver to message one another over the connection with arbitrary metadata in [[XML]] form.<ref>{{cite web|url=http://www.content-technology.com/standards/?p=578|title=NewTek Announces NDI – Open Protocol for IP Production Workflow - Technical Standards|website=Content-technology.com}}</ref> This directional metadata system allows for functionality such as active [[Tally light|tally information]] fed back to sources to understand that they are on-air (program / preview). NDI also allows senders to determine the number of connected receivers, so they can skip unnecessary processing and network bandwidth utilisation when there are no NDI receiver clients connected. NDI Receivers can opt to connect to various combinations of streams, to support things like audio-only or metadata-only connections where video is not required.