What is SDI Video?

The answer to “What is SDI video?” is as simple as: “A video transmitted using the digital standard SDI (Serial Digital Interface)”.

The SDI interface standard marked a revolutionary transition from analog to digital video infrastructure. The SDI standard was designed to permit transport and synchronously switch audio/video from source to destination without disturbances and to mitigate the generational quality issues associated with analog video and audio. The isochronous nature of SDI is straightforward for live, continuous video inside the studio, and for long distance transport. However, these capabilities are not as easily accomplished in a file-based, non-real time, or streaming media environment.

In this article we’ll explain what an SDI router is, talk about what SDI interface standards there are, and discuss the future of SDI and the on-going migration to IP broadcasting.

SDI interface standards

The SDI interface was developed in 1989 by the Society of Motion Picture and Television Engineers, more commonly known as SMPTE. But as the world has evolved, so have the SDI interface standards. Since the release of the SD-SDI interface, seven additional SDI interface standards have been developed to support the continuously increased resolutions, higher bitrates, and more colors. The latest addition to the SDI interface family made their debut in 2020, where the 24G-SDI interface was published.

Name Release yearSMPTE-standard Bitrates Example video formats
Standard definition SDI (SD-SDI)1989259M143 Mbit/s, 177 Mbit/s, 270 Mbit/s, 360 Mbit/s 480i, 576i
High definition SDI (HD-SDI)1998292M540 Mbit/s480p, 576p
Enhanced definition SDI (ED-SDI) 2000344M1.485 Gbit/s & 1.485/1.001 Gbit/s720p, 1080i
Dual link HD-SDI2002372M2.970 Gbit/s & 2.970/1.001 Gbit/s1080p60
3 Gbps SDI (3G-SDI)2006424M2.970 Gbit/s & 2.970/1.001 Gbit/s1080p60
6 Gdps SDI (6G-SDI)2015ST 20816 Gbit/s1080p120, 2160p30
12 Gdps SDI (12G-SDI)2015ST 208212 Gbit/s2160p60
24 Gdps SDI (24G-SDI)2020ST 208325 Gbit/s2160p120, 4320p30

The SDI video router

The SDI system is nearly used universally for the transmission of uncompressed, unencrypted digital video signals for professional broadcasting. Widely adopted among industry professionals, the SDI video router was designed to deliver serial digital input signals in a point-to-point, one-way structure. The SDI video router also ensured consistent delay and performance, regardless of the number of active signals being routed and switched.

SDI has been an incredibly successful interconnection technology. It has served the industry for more than 30 years and has evolved over that time with an increase in capacity such as 12G and 24G SDI interface. Because of this, there is a vast wealth of equipment installed in production and delivery facilities around the world, which interfaces to other pieces of equipment through one-signal-per-wire coaxial SDI cables. SDI equipment is proven and its workflows are embedded among broadcast engineers the world over.

Migration to IP Broadcasting, one-upping the HD-SDI video router

However, the television industry is currently facing the need for tremendous amounts of content distribution as well as supporting new 4K UHD formats that require the switching of uncompressed video at bitrates of 12Gbps and above. The need for increased bandwidth and better connectivity, combined with the growing over-the-top (OTT) market, simply outweigh the capabilities of what the traditional SDI/HD-SDI video router can offer.

It is simply impractical, or even impossible, to accomplish this with broadcast SDI video router designs. Broadcasters have begun to embrace commercial off the shelf (COTS) data center class IP networking to enhance the efficiency of the broadcast plant. More importantly, the flexibility provided by packet-based architectures effectively supports the new reality of agile production and multi-faceted distribution strategies. IP brings the additional benefit of leaner and more flexible economics instead of high-cost bespoke broadcast infrastructure such as the HD-SDI router. This transition from legacy broadcast systems to IP meets both the near and long term demands of production, contribution, distribution, and content delivery.

The future of the SDI interface and IP

The transition from SDI to IP broadcasting infrastructure in professional television will take several years. Legacy SDI routers, SDI interfaces, and new IP networks will coexist for a number of years during the migration to a COTS infrastructure.

During this transition, a smooth operational integration between the old (SDI/HD-SDI router) and the new (IP) must be accomplished. Production staff should see no material difference in operations whether a particular project’s signals are SDI-based or IP-centric. The ability to efficiently process and seamlessly route existing SDI video streams as well as IP streams across a hybrid infrastructure should be enabled.

Smooth Transport Over Any Infrastructure

Net Insight created the Nimbra and the Aperi platforms to enable ultra-reliable broadcast grade long-distance media networking across any infrastructure – IP or cloud. Bricks and mortar premises, public or private data center.

As technology advances, Net Insight has innovated the next level of media transport designed to on-ramp your workflow to the cloud. Nimbra Edge is a fully cloud-based media transport solution designed for private or public cloud environments. It could be described as a “virtual video router in the cloud”. It augments existing devices such as Nimbra 400 by offloading complexity to its cloud-based backend – drastically simplifying the network architecture.

With an open standards-based approach to networking, Nimbra Edge connects to any media device supporting leading protocols RIST, SRT, or Zixi for the ultimate in reliability, flexibility, and versatility. Providing lossless media transport over any type of infrastructure, the Net Insight Nimbra gives you the peace of mind to focus on what really matters – your content and the creation of it.

If you have any further questions regarding what SDI video is, what SMPTE 2210 is, the different SDI interface standards, or the advantages of transmitting video over IP, contact Net Insight.


World’s largest Nimbra networks to HD

EBU has selected Nimbra platform for the Eurovision fiber network

The European Broadcasting Union (EBU)

World’s largest alliance of public service media organisation

Since 2004, when the EBU selected Net Insight’s Nimbra platform, the EUROVISION Fibre Network (FiNE) has evolved with Net Insight’s latest products and features.

The EUROVISION satellite and fibre network is one of the largest and most rock solid in the world. It delivers more than 80,000 hours of programming every year, the majority of which is live sports. Its undisputed reputation for flexibility and reliability is reflected in the prestigious events it regularly carries on the EUROVISION network.

“We continue our solid relationship with Net Insight for the development of our network since we aim to be the standardbearer for QoS and reliability around the world.”

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SDI (Serial Digital Interface) video is a standard for transmitting digital video over coaxial cable, known for its reliability and quality in professional broadcast.

SDI has evolved with increasing capacities, such as 12G and 24G SDI interfaces, to support higher resolutions and bitrates.

Traditional SDI routers face challenges in supporting high-bandwidth demands and new 4K UHD formats due to their limited capabilities compared to IP-based solutions.

The transition involves adopting COTS data center class IP networking for improved efficiency and flexibility, moving away from bespoke broadcast infrastructure like HD-SDI routers.

Net Insight offers the Nimbra platform, designed to support ultra-reliable long-distance media networking across any infrastructure, facilitating the transition from SDI to IP.​