Videography – February 1999

The Router is Dead! Long Live the Router!
By Sheldon Liebman

Quick! What's the fastest network in a video facility? The answer depends on exactly what type of equipment is installed, but it could very possibly be the "video" network, especially if the studio has installed one of the newest Routing Switchers capable of handling HDTV signals. Operating at speeds up to 1.5 GigaBits per second (Gbps), HD capable video networks far exceed the bandwidth of many types of computer networks, including GigaBit Ethernet, SSA-80 and all versions of SCSI. In theory, Fibre Channel operates at up to 2 Gbps, but most installations don't actually achieve that speed.

As more and more of the video we transmit is digital, the overlap between a computer network and a video network is increasing. The result, at some time in the future, may be a complete merger of these two areas, resulting in the computer as router or the router as computer. When will that actually occur, if at all? That's not an easy question to answer. However, Videography spoke with a number of high-end router manufacturers in an attempt to define where this technology is going. Nobody wanted to be quoted directly, but here is the result of our research.

Digital Meets Analog
Earlier this year, we wrote about the current generation of routers that use tie-line management to link analog and digital video signals together. In some cases, two boxes are linked by external converters. In at least one case, both digital and analog cards can be placed in the same frame. This trend should continue, allowing facilities to mix and match any number of analog and digital inputs as they configure their routers.

As part of this process, the control software will need to become more flexible and more intelligent, since a single router will have a virtually unlimited number of ways it can be configured. If a separate computer is used to control the system, it may even have a video port that plugs into the router to allow digital video streams to be fed directly in the system.

Your Rates or Mine?
The world is shrinking, which means that more and more facilities are working with both analog NTSC and PAL video. Clearly, these two formats do not travel through routers at the same rate. However, the additional information per frame in PAL video is offset by the lower number of frames transmitted each second. As a result, there are some routers today that can handle NTSC and PAL video at the same time.

These routers don't necessarily convert one to the other, so you can't feed NTSC into Input 1 and get a PAL version of the content from Output 2. However, the units can accept both vertical reference inputs so that only a single network is necessary. If two references can be accepted, why not 3 or 4 or even 10? By adapting routers to handle even more references, any interlaced format could theoretically be fed into a single unit, even 1080i.

Progressive Thinking
The shift from interlace to progressive scan is one of the biggest obstacles the video industry has ever had to face. Interestingly enough, the computer industry has been dealing with it for years. Since all broadcast video (until very recently) has been interlaced, anyone who has ever tried to view a video window on a computer screen is familiar with the process of converting interlace to progressive scan. In the other direction, scan converters have been taking progressive scan source material from computers and outputting interlace video for years. Sometimes the resolution needs to be changed, as when the computer is set to operate at 1280x1024, and sometimes the only real change is from progressive to interlace, as when the computer is operating at 640x480 resolution with a 60 Hz refresh rate.

As routers move forward, it makes sense that they will incorporate these technologies to allow movement between interlace and progressive scan formats with a minimum of difficulty.

You Say Compouter, I Say Rouputer
The more intelligence a router has, the closer it becomes to being a computer in its own right. As this transition takes place, the computer acting as a controller will incorporate more routing functions and the router itself will incorporate more smarts. Ultimately, the router will be a computer, or the computer will turn into a router. Today, multiple computer networks are linked together by individual computers acting as bridges between them. For example, a Fibre Channel network can be linked to an Ethernet network by utilizing a single computer containing both types of network adapter cards. Information from one network that needs to move the other is routed through the internal bus of this bridge computer. The control software handles any data format changes that need to occur.

Shifting to the example of video routing, imagine that same type of computer with a very large number of slots and an incredibly fast bus structure. A card in each slot is designed with one input and one output of a specific format and the ability to convert between this specific format and the HIGHEST common denominator in real-time. Perhaps this format is one of the many already available, but it could also be something that's invented specifically for this purpose. Using the highest common denominator ensures that signals can be mixed and matched in any manner with a minimum of information loss. Perhaps there is a "pass-through" setting that allows a signal to move through unchanged when the controller knows that the input and output are the same format.

There is one other piece to this puzzle - these cards don't have to just deal with "video" formats. Perhaps one will be designed to accept files from AVID non-linear editing systems. Another might be set up for Alias/Wavefront animation data. The possibilities are endless, but the goal is the same - to seamlessly route any video and data format throughout a facility and to have it available in any format, at any location, at any time.

When digital video formats were first introduced, a lot of companies claimed it would signal the end of videotape. That still hasn't happened, and it's unclear how long it will take for this "router of the future" to be created. Perhaps the router as we know it will always exist, just as most people now believe videotape must continue to exist.

We can't say for certain that the vision presented in this article will actually happen or when it will take place. We do know that small steps are being taken daily to move in this direction and when enough small steps occur, a giant leap is possible. The router is dead! Long live the router!

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