Users and manufacturers plan for a future without SDI.
At the outset, let me say that I believe that equipment using the ubiquitous Serial Digital Interface or SDI will be around for a long time, perhaps 10 years or more. However, there is no question that a transition has already begun. That transition is a move away from broadcast infrastructures that are based on specialty broadcast equipment and interfaces such as SDI and AES to IT-based packet networks such as Ethernet and IP.
The transition from SDI to networks
When speaking to audiences, whether in the United States or abroad, over the last several years I have asked how many people are planning to purchase a large SDI router in the next five years. Usually, a hand-full of hands go up. Next, I ask who expects to be purchasing a large SDI router in 10 years. I have never had a single hand go up.
This poses an obvious follow-on question: If people are not planning on buying SDI routers in 10 years, what are they going to be using for their core infrastructure for professional video? The answer is obvious — some sort of packet-based network technology.
But this just raises more questions. Will people make a dramatic switch from SDI to networks, or is this transition going to take place over several years? (Again, an obvious answer: The transition takes place over several years.) If we are talking about a transition that takes several years, when will we start? Again, there is an obvious answer. I have not been in a single professional media facility in the last 10 years that has not had a professional media network (a network that is used to move professional content from place to place in a facility) in place.
In some cases, these networks are based on carrier-class, high-availability equipment, and they are maintained by highly-trained networking professionals. In other cases, these networks have evolved over time, perhaps starting with installations in audio or graphics, and expanding into other areas over time. But in all cases, these networks have evolved to stand alongside traditional broadcast infrastructures, and in all cases, if you disabled these networks, the professional media organization would suffer significantly.
So, in short, the transition from SDI to networks began years ago. This may come as a surprise to some of you, but think about it: This significant change is already occurring. If you were at IBC this year, you would have seen any number of professional broadcast products taking advantage of packet-based networking technology. The shift to networking seems to be well under way. But there is abig problem.
SDI and AES interfaces are very well defined, standardized, and there are countless interoperable implementations. The same cannot be said about implementations of professional media networks. In fact, the only standard that has been widely adopted relating to the transmission of professional video over IP networks is SMPTE 2022, and the authors of this suite of documents will tell you that they are intended for transmission between facilities, not inside facilities. Nothing else is even on
Given that it has taken the industry somewhere between two and three years to come up with a standard as significant as SDI, and given that even after adoption, it is likely to take another five years before such a standard is widely implemented in the industry, we are in a bind. Early proprietary implementations already exist. It appears that no one plans on buying any core SDI equipment in 10 years. If it is going to take us seven to eight years before a standardized replacement is developed and becomes widely implemented, we probably should get started. Now.
The European Broadcasting Union (EBU), the Society of Motion Picture and Television Engineers (SMPTE) and the Video Services Forum (VSF) agree. They have formed a group called the Joint Task Force on Networked Media, abbreviated JT-NM.
Generally I am not that big a fan of mission and vision statements. But in this case, these statements answer, fairly succinctly, the questions of how this group is going to function and why the group was formed. First, the how. The mission statement of the JT-NM describes how it intends to perform its work and what the expected output is:
In an open, participatory environment, help to drive development of a packet-based infrastructure for the professional media industry by bringing together manufacturers, industry associations (standards bodies and trade associations) with the objective to create, store, transfer and stream professional media.
Why do this? The vision statement describes what the task force hopes the future will be like if it is successful:
New business opportunities are enabled through the exchange of professional media, including file-based and live content, across a network taking advantage of the benefits of IT-based technology at an affordable price.
But before we rush off to create a solution, there are a couple of additional significant questions. First, is there any business reason to do this? Most engineers have learned that if we cannot describe what the technology will do for the business, then that technology is going nowhere — especially if it is costly to implement.
The second question is key: Are there things that you can only do with SDI? This turns out to be a controversial question depending on which side of the infrastructure argument you come down on. But if you think about it, as engineers, we should be impartial about the technology and look to employ the best technological solution in any given situation.
It turns out that there are a number of technologies available now, or available in the near future, that could allow networks to carry professional video as reliability and with functionality very similar to SDI. But we should be careful. When the industry went throughout the transition from videotape to files, we first treated files just like tape, missing many of the benefits of this transition.
It turns out that to this point, no one had asked end users what they wanted in terms of functionality in professional media networks. What are the business drivers? What new things could be enabled from a business perspective if standardized interfaces for media networks were available? The JT-NM started its work by collecting more than 150 business-driven use cases in order to determine the drivers this transition. These use cases have been published and may be viewed at http://tech.ebu.ch/groups/jt-nm.
With use cases in hand, the JT-NM set out to condense these stories into 16 “super user stories” that capture the essence of the original contributions. It then authored a Request for Technology (RFT) that asks for technological responses that serve to meet one or more of the requirements listed in the user stories. Once responses are received, the JT-NM intends to perform a gap analysis, identifying any areas where there are business use cases, but no technology has been submitted. Once this work is completed, the task force will identify future work.
Several important ideas have come out of the user stories. The first is that many media companies stress that data needs to be treated as a first-class citizen. For years, data has trailed alongside of what was generally agreed to be the most important asset, the content (video and audio).
Now media companies realize that data such as closed captioning, camera position data, rights information and so on is as critical as the pictures and sound themselves. Having infrastructures that treat these items equally and in the same technical environment is critically important.
A second point coming out of the user stories is that the era of purpose-built broadcast and professional media infrastructures is largely coming to a close. It is critical to the future of our business that we be able to leverage the billions of dollars spent worldwide on IT infrastructures. The key is in understanding how we can adapt these technologies to meet our business needs.
Finally, there may be another shift on the horizon — the death of files. I know many of us are just getting our minds around the transition from video tape to files, but in the not too distant future, the notion of a movie existing as a single grouping of bits stored on some sort of file system will be passé.
It is much more likely that any end-viewer experience is going to be comprised of any number of “grains” of content and data that are brought together “just in time” in order to create that particular viewing experience. The infrastructures needed to support the creation and exploitation of professional media content are likely to be very different from existing SDI plants. In fact, the transition has already begun.
—Brad Gilmer is a co-chair of the Joint Task Force on Networked Media, executive director of the Video Services Forum, executive director of the Advanced Media Workflow Association and a consultant to the professional media industry.