NDI

NDI (Network Device Interface) is a modern IP-based video streaming protocol developed by NewTek. It allows multiple video sources and displays to communicate over standard Ethernet networks without requiring specialized broadcast infrastructure. NDI has rapidly become the standard for professional video distribution in production, streaming, and hybrid broadcast environments.

See also: glossary/ndi for a quick-reference summary.

What NDI Does

NDI encodes video (and optionally audio, metadata, control signals) into compressed IP packets suitable for Ethernet transmission. Unlike broadcast sdi, which requires dedicated point-to-point connections, NDI leverages existing network infrastructure. Multiple sources stream simultaneously on a single network; any device can receive any stream with software authorization.

Key concept: NDI treats video like network data. Standard switches, routers, and cabling carry video alongside email, web traffic, and other network services.

Technical Specifications

Compression

NDI uses proprietary compression (not H.264 or H.265):

• Visually lossless at typical bitrates (100-400 Mbps for HD, 400-1000 Mbps for 4K)
• Frame-accurate: no B-frame reordering or delayed decode (important for live production)
• Latency: typically 1-3 frames at Ethernet speeds, acceptable for most applications
• Quality prioritizes live production needs over archival fidelity

Bandwidth Requirements

• 1080p @ 60fps: ~125 Mbps typical
• 2160p (4K) @ 60fps: ~500 Mbps typical
• 4K @ 120fps: ~1000 Mbps (requires 10G Ethernet)

These numbers assume 1Gbps Ethernet is available. Network congestion reduces quality gracefully; NDI adapts to available bandwidth.

Protocol Layers

NDI runs over standard IP (UDP multicast or unicast):

• Automatic discovery: NDI sources and receivers broadcast presence; no manual configuration
• Firewall-compatible: operates on standard ports when properly configured
• Integration with av-over-ip ecosystems: often paired with dante, aes67, or other IP-AV protocols

Practical Advantages for AV Integration

Cost & Simplicity

NDI uses standard Gigabit Ethernet switches and cables. No specialized broadcast infrastructure, no point-to-point SDI cabling. A conference room with modern network infrastructure can stream 4K video with software installation alone.

Flexibility & Scalability

Add video sources or destinations by running software; no rewiring. A 100-person hybrid meeting distributes video to all participants simultaneously from a single encoder. Traditional systems require dedicated matrix switching; NDI handles it in software.

Camera Integration

Many modern cameras (PTZ, fixed, streaming) offer native NDI output. This reduces the need for expensive encoder/decoder hardware. Producers can capture, mix, and distribute video entirely in software.

Hybrid Broadcast

NDI seamlessly bridges traditional broadcast (SDI) and IP workflows:

• SDI camera → NDI encoder → software mixer → NDI output → SDI decoder → broadcast
• This hybrid approach is increasingly standard in remote production and live events

Network Requirements & Considerations

Bandwidth Planning

A single 4K stream consumes ~500 Mbps. Multiple simultaneous 4K streams require:

• 2 streams: 1000 Mbps (saturates 1Gbps network)
• 4+ streams: 10 Gigabit Ethernet necessary

Many installations underestimate bandwidth. A 1Gbps network can carry one 4K stream comfortably but struggles with 2-3 simultaneous streams plus other traffic.

Network Isolation & VLAN Configuration

Professional installations isolate video traffic via vlan-configuration-for-av:

• Dedicated VLAN for NDI reduces contention with office traffic
• QoS (Quality of Service) prioritizes video packets
• Network configuration becomes as critical as AV hardware

Latency Tolerance

NDI introduces 1-3 frame latency, acceptable for most production but problematic for:

• Lip-sync critical applications (requires synchronization)
• Interactive gaming or remote control (noticeable delay)
• Live event switching with tight coordination

Audio sync requires careful buffering; video-only streaming is simpler.

Security & Access Control

NDI has built-in user/password authentication and group management. Sources broadcast availability but not the video stream itself; receivers must request access. This is convenient for small teams but requires planning for large distributed systems.

Some installations use firewall rules or VLAN isolation for additional security, particularly if streaming outside the organization.

Common Pitfalls

• Bandwidth underestimation on busy networks: A single 4K stream saturates a 1Gbps network; multiple 4K streams require 10Gbps infrastructure; many integrators underestimate bandwidth before design
• NDI|HX vs full NDI quality tradeoffs: NDI|HX compresses more aggressively for remote/internet use but loses quality; verify whether full NDI or NDI|HX is appropriate before commissioning
• Firewall blocking mDNS discovery: NDI auto-discovery uses multicast DNS; firewalls or network policies blocking mDNS prevent sources/receivers from finding each other; ensure firewall rules allow mDNS on AV VLAN
• Network congestion during peak usage: NDI quality degrades gracefully with congestion, but video artifacts appear during high-traffic periods; monitor network during live events

NDI vs. Traditional Video Distribution

Real-World Applications

Remote Production

A field camera streams NDI over the internet to a studio 1000 miles away. The studio software mixer receives the stream, switches it live, and distributes to broadcast. This was impossible with traditional SDI; NDI made it practical.

Hybrid Meetings

A conference room camera streams via NDI to Zoom/Teams. Participants see professional-grade video instead of compressed RTMP. Simultaneously, the room's local display shows the presenter. Both work from one camera source.

Distributed Education

A university lecture streams via NDI to multiple buildings. Students join from classrooms via VLAN-isolated NDI receivers. Bandwidth is shared across campus network; no dedicated video infrastructure required.

Live Event Switching

A multi-camera concert records via NDI encoders. A producer software-switches camera feeds in real time, streams to YouTube/Twitch, and simultaneously records all feeds to NAS storage. Single operator; minimal hardware.

Integration with Other Systems

With Dante Audio

NDI streams video; dante (or aes67) streams audio independently. Combined they create complete broadcast-grade systems over standard networks.

With av-over-ip

NDI is one of several IP-based AV protocols. Others include Dante, AES67, SMPTE ST 2110 (broadcast standard). Choosing NDI vs. alternatives depends on ecosystem and existing infrastructure.

With Control Systems

NDI sources can be controlled via REST APIs or custom protocols. Control systems orchestrate camera movements, switching, and recording using standard integrations.

Limitations & Practical Issues

Network Dependency

Video quality depends entirely on network health. Congestion, packet loss, or misconfiguration causes visible artifacts. Network-savvy integration is critical; many AV integrators underestimate this.

Decoding CPU Requirement

Receiving NDI video requires CPU resources. A computer decoding 4 simultaneous NDI streams consumes significant CPU. Budget hardware accordingly, especially for complex mixing.

Ecosystem Lock-in

NDI software and encoders/decoders are NewTek/Vizrt products. While third-party support exists, the ecosystem is less open than broadcast standards. Long-term availability and cost are considerations.