a set of rainbow SDI cables connected to the back of a server

For all the talk of IP-connected, virtualized software architectures, you might be forgiven for thinking that SDI has gone away. Many executives in our industry have delivered its eulogy ― all prematurely.

SDI is real and useful ― the world standard in digital signals for almost 40 years.  Evolved, of course, from SD to HD to 3G, and now pockets of 6G and 12G for UHD.  That is an impressive upgrade when you remember that UHD is 20 times the original standard definition data rate!  (That said, our IT colleagues have gone from 10 Mbits to 50 Gigabits per lane in the same amount of time ― a 5000x upgrade!)

In most facilities today, there is still a lot of SDI equipment in the racks.  Nobody wants to throw any of it away; it’s still good, and one day you might need it. Even in new projects, SDI has its place and space. And when it fits the requirements, SDI is cost-effective and low risk. 

But we also have to acknowledge the limitations of SDI. It is a point-to-point communication, which means every source and destination has its own socket on the back of the router. And no matter how far ahead you believe you have planned, if you have, say, a 288 x 288 SDI router, then as sure as the sun rises in the morning, someone will have a pressing need for a 289th source. Meetings will be held to determine who will lose a router port.

SDI with embedded audio is great when you want both signals to go to the same place; they both get there, and they stay in sync.  But when you only want one, or you need to do some audio channel shuffling, then you have to de-embed the audio, process it, perhaps route it separately, then re-insert it ― probably with some manipulation of delay. 

In the development of the SMPTE ST 2110 architecture, we leveraged the good of SDI ― uncompressed video quality, consolidating signals into shared cables ― while also making all the parts independently routable.  In the SDI plant, each wire carries one “program.”  In the IP plant, each 100G cable carries up to 32 (1080p) programs, in each direction.  Common-market 1RU 100G switches terminate 32 of these 100g links, forming a “router” up to 1024x1024 with audio and ANC breakaway capability.  The SDI equivalent consumes a whole rack for half that capacity.

It’s a mistake to think about SDI-IP as an either-or proposition

Our industry has been integrating new technologies since the dawn of television; just during the story arc of SDI, we went through 10 tape formats before getting rid of tape entirely.  None of these shifts happened overnight, but all happened over time ― while keeping the stations on the air.

And so it is with ST2110 and SDI: it makes good sense, over time, to move to an ST2110 interconnection architecture. The technology is widely available from all the vendors you are likely to deal with.  And it is field proven ― lots of television is made today with ST2110.  But equally, most of today’s ST2110 plants still have a fair bit of SDI equipment inside them, and have workflows built around it.   A key principle of the ST2110 architecture is its ability to interoperate reasonably with SDI, and this too is proven in practice every day.

I believe there will still be significant amounts of SDI equipment in operation with the world’s broadcasters 10 years from now. At Imagine, we continue to offer market-leading SDI products, like our Platinum routers, X100 processors, and long-revered 6800+ and Selenio MCP modular lines.  Feature-packed and still rolling hard. 

But increasingly, SDI equipment is part of hybrid architectures that protect and extend the existing investments, while migrating each function to its ST2110 equivalent at a natural pace. Our Selenio Network Processor (SNP) is selling extensively around the world, in large part because it provides a transparent, seamless bridge between SDI and IP and performs valuable workflow functions (processing, conversion, multiviewer, etc.) in both (SDI and IP) domains.

Decisions about architecture, about new workflows, about the balance between the machine room and the cloud are for you to make, at whatever pace works with your business. Be assured that, while we have leading solutions for the future, our decades of experience with today’s (SDI) plants and technologies is at the root of everything we do.


July 8, 2021 - By Imagine Communications
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portatif of Steve Reynolds


Steve Reynolds

Steve Reynolds is President of Imagine Communications, a global leader in multiscreen video and ad management solutions that broadcasters, networks, video service providers and enterprises around the world rely on to support their mission-critical operations.

Steve brings 25 years of technology leadership in the video industry to Imagine Communications. He has served as the CTO at Imagine Communications and Harris Broadcast, Senior Vice President of Premises Technology at Comcast, Senior Vice President of Technology at OpenTV, and CTO at Intellocity USA.

Steve earned a MS in Computer Engineering from Widener University and BS in Computer Science from West Chester University. As the Chairman of the AIMS Alliance and a member of SMPTE and SCTE, he has participated in numerous standards-making bodies in the cable and digital video industries. Steve also holds over 40 patents relating to digital video, content security, interactive television and digital devices.