HON’s Wiki # Network Device Interface (NDI)

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Contents

• Info
  • Encoding
  • Transport Protocols
  • Recommendations
• Usage
  • NDI Tools
  • NDI SDK
  • OBS NDI Plugin

A network video protocol by NewTek.

Info

• A royalty-free protocol by NewTek for sharing video over IP in a standard Gigabit LAN (or better).
• Provides multiple high-quality, low-latency and frame-accurate video and audio feeds.
• Uses mDNS by default for autodiscovery. Alternatively, one or more discovery servers may be used.
• Supports multicast sending, but it’s disabled by default.

Encoding

• The normal, high-bandwidth encoder is simply called “NDI”.
• NDI provides multi-generational stability, meaning repeated encodings don’t degrade quality.
• Has a technical latency of 16 video scan lines, although typically lower in implementations.
• “NDI|HX”, meaning “NDI High Efficiency”, uses much lower bitrate and is appropriate when bandwidth is limited.

Transport Protocols

• Reliable UDP: Supports very high-latency networks. Has built-in congestion control and loss recovery and no head-of-line blocking.
• Multipath TCP: Uses multiple NICS and multiple network paths.
• Single TCP: Nothing special.
• UDP with FEC: For when reliable delivery is not required. Has forward error correction (FEC).

Recommendations

• The network must be high-bandwidth, low-latency, jitter-free and highly available.
• The network should be mostly dedicated to NDI streams.
• The network topology should be designed with requirements in mind.
• Gigabit, consumer off-the-shelf (COTS) equipment is generally good enough.
• While NDI supports using multiple NICs and may automatically distribute streams to different NICs, NIC teaming/aggregation is often preferred if possible.
• The network should be optimized for multicast traffic with IGMP if multicast sending is enabled.
• Maximum throughputs for streams:
  • NDI 1920x1080 60Hz: 132Mb/s
  • NDI 1920x1080 60Hz (with alpha): 165Mb/s
  • NDI 3840x2160 60Hz: 249Mb/s
  • NDI 3840x2160 60Hz (with alpha): 312Mb/s
  • NDI|HX 1920x1080 60Hz: 15.9Mb/s
  • NDI|HX 1920x1080 60Hz (H.264 & HEVC): 10.9Mb/s
  • NDI|HX 3840x2160 60Hz: 30.0Mb/s
  • NDI|HX 3840x2160 60Hz (H.264 & HEVC): 21.0Mb/s

Usage

NDI Tools

• Contains tools for e.g. sending streams, receiving streams, sending test streams, routing streams, bridging streams etc.
• Contains plugins/extensions to VLC, Premiere Pro and After Effects.
• For Windows and Mac only.
• Download

NDI SDK

• The NDI SDK is used to develop native NDI applications.
• For targeting Apple, Android, Linux/ARM, Windows etc.
• Download

OBS NDI Plugin

See OBS.

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