Network Device Interface (NDI) is a royalty free standard developed by NewTek to enable video-compatible products to communicate, deliver, and receive broadcast quality video in a high quality, low latency manner that is frame-accurate and suitable for switching in a live production environment. The protocol is designed to be highly robust and is used in many network-connected video devices. It has been widely adopted and the installed based for NDI exceeds 1 million users .
Video Network Device Interface
Technology
Whilst the NDI technology has been developed by NewTek it is made available to anyone with a royalty-free license, and has been widely adopted by many broadcast vendors, including those sometimes seen as competition for NewTek's own products. A free code library and examples is available for Windows, Linux and macOS. NDI has also been ported to iOS, Android, Raspberry Pi, and FPGA. There is also a range of free NDI tools for end users provided by NewTek, Sienna, vMix and others.
Unlike other professional IP Video protocols such as SMPTE 2110, SMPTE 2022-6 and ASPEN which require 10 Gigabit networks, NDI is designed to run over existing 1 Gigabit networks allowing easy adoption of the protocol without new infrastructure. This is achieved through the use of video data compression with the NDI codec which delivers 1080 full HD video at VBR data rates typically around 100Mbit/sec.
NDI uses the mDNS (Bonjour / Zeroconf) discovery mechanism to advertise sources on a local area network, such that NDI receiving devices can automatically discover and offer those sources. Sources are created using an arbitrarily selected TCP 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 UDP Multicast or Unicast with FEC(Forward_error_correction) instead of TCP, and can load balance streams across multiple Gigabit NICs without link aggregation.
NDI carries video, multichannel uncompressed audio 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. This directional metadata system allows for functionality such as active 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.
Maps Network Device Interface
Comparison with other protocols
Other IP Video protocols emerging for use in professional video production (rather than IP Video used for distribution to end users) include SMPTE 2022, SMPTE2110, ASPEN (which appears to have been largely superseded by SMPTE2110) and Sony NMI. There are clear differences in the technology used by these protocols.
*The TICO codec can be used to compress UHD by 4:1 so an encoded stream can be carried along a SMPTE_2022-6 channel at the same uncompressed bandwidth as HD. SMPTE 2110 with TR-03 also offers the potential to use TICO. This requires a proprietary encoder and decoder which are generally implemented as silicon on each end. * * NDI v1.0 was pure TCP. Later versions included options for UDP Unicast and Multicast as appropriate and FEC. NDI HX is generally UDP but uses TCP control commands.
History
NDI was publicly revealed by NewTek on 8 September 2015 and was demonstrated at the IBC broadcast exhibition in Amsterdam that week. The first device shown using NDI was the NewTek TriCaster which delivered an NDI feed from each of its SDI inputs as well as 4 output feeds from its vision mixer. TriCaster could also receive up to 2 NDI sources from other devices (increased to 12 in later releases and up to 44 in NewTek's IP Series ).
NDI devices from other vendors followed during 2016. The first 3rd party products came from Gallery Sienna and included an NDI signal generator for macOS, a desktop scan converter for macOS and the NDICam camera app for iPhone which delivers a native NDI stream from iOS devices. Since 2016 Sienna's NDI based family has grown to 16 products across 4 platforms (macOS, Ubuntu, iOS and Windows).
NewTek had previously created a predecessor of NDI called AirSend to get video from external devices into their TriCaster products. AirSend had been implemented by a number of CG manufacturers including VizRT and Chyron. In order to quickly bring these products into the NDI space, NewTek created a new driver to replace the existing AirSend driver, which could be installed on these existing AirSend compatible devices, instantly converting them to NDI compatible devices with no change required by the original CG vendors.
Another early adopter of NDI was VMix, a Windows based vision mixer which offers NDI inputs and outputs. The biggest increase in the NDI installed base came when live streaming application XSplit added support for NDI.
Later in 2016, NewTek delivered NDI 2.0 which added features including support for service discovery across subnets. In the first half of 2017, BirdDog began demonstrating and shipping BirdDog Studio NDI - a PoE powered portable FPGA based NDI encoder with HDMI and SDI inputs with full Tally, supporting up to 1080p60 video resolutions. On 12th July 2017 NewTek announced NDI 3.0 which added multicast, NDI/HX and other new features, introducing support for specific PTZ Cameras with H.264 chipsets and updated firmware.
In April 2018 at the NAB Show, Microsoft announced they had added NDI support to Skype for Content Creators, introducing NDI to hundreds of millions of new users. Other announcements at NAB2018 included NDI 3.5, and new NDI support from vendors including EVS and Avid
Use in Wifi and Wide Area Networks
NDI was designed to work on good quality gigabit local area networks using TCP and Bonjour (mDNS) technologies. In order to work across subnets which don't pass mDNS, NDI supports a mechanism known as NDI Access which allows manual entry of the IP address of machines on other subnet which may be running NDI sources.
Mobile apps like NDICam have shown that NDI can also work well on Wifi networks, although the need for c. 100mBit communications requires very good quality communication between the device and the Wifi router to achieve full frame rates.
NDI 3.0 with NDI HX introduced a lower data rate codec which can be used more easily over Wifi and even potentially 4G connections.
Some NDI adopters have run the protocol across medium distance Fibre connections up to 15 km, although NDI's use of the TCP protocol make it less suitable for longer distance, high latency connections due to factors such as Bandwidth Delay Product and TCP packet loss recovery. NDI HX uses a lower data rate and as such is more suitable for WIFI.
To provide an extension of NDI to wide area networks, the Sienna Cloud for NDI protocol uses node gateways in each LAN to bridge NDI sources across continents.. In July 2017, using Cloud for NDI USSSA (United States Speciality Sports Association) successfully made the first truly wide area network NDI sports coverage with 5 cameras backhauled across the public internet from a stadium, to 200 miles away into an NDI based production gallery.
CPU architecture support
NDI, when running on x86 architectures, requires CPU's that include the SSSE3 (Supplemental Streaming SIMD Extensions 3) instruction set. Most Intel CPU designs starting in 2006 have this instruction set, AMD added support starting in 2011.
While not a requirement, NDI will take advantage of AVX (Advanced Vector Extensions) and AVX2 instructions sets for additional performance. While NDI itself doesn't require these instructions, applications might.
NDI can run on 32-bit or 64-bit CPU architectures. NDI will offer higher performance when running with 64-bit applications.
NDI is available for ARM based systems with encode support. Decode support is still forthcoming.
NDI HX Devices are typically send-only and based on proprietary platforms with hardware H.264 encoder chips. Examples are NDI HX PTZ Cameras, and the NDI Connect Spark SDI to NDI HX box. The NDI Stream itself is formed at the stream consumption end via the platform specific NDI HX driver, presenting the same uncompressed data to the application software consuming the NDI source regardless of original HX source hardware and compression.
NewTek and Birddog have both developed FPGA implementations of NDI. In April 2018 NewTek announced the Connect Spark Pro which was their first FPGA based NDI product.
Adoption
The NDI Protocol has been widely adopted by a diverse variety of software and hardware vendors. The table below includes a partial list of products known to support the NDI Protocol
References
External links
- "The ABCs of NDI - NewTek's Video Over IP for Everyone | Acquisition". Content-technology.com. 2016-09-26. Retrieved 2017-05-23.
- "Alpha Video Releases White Paper on Broadcast IP Protocols". AvNetwork.com. Retrieved 2017-05-23.
- "NDI Central IP Video Production News | NewTek". Ndicentral.com. Retrieved 2017-05-23.
- "IP Video: Its More Than One Thing, And It Needs More Than One Solution". thebroadcastbridge.com.
Source of the article : Wikipedia
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