John Luff /
06.01.2005 12:00 PM
Production switchers


The UK’s Neon Broadcast Services employs an SD/HD Kahuna production switcher from Snell & Wilcox in its newest mobile truck.

The HD factor

There was a time, long ago and far away in another galaxy, when all television was essentially live. Only kinescope film techniques allowed recording live television for later playback. Film production allowed post-production without electronic cameras, but all the rest was truly live. The need to do most production in a live environment, complete with the (much) simpler effects that early monochrome hardware could support, spawned the development of the video switcher. The simplest had mechanically interlocked buttons and maybe simple fades. “Supers” were developed to allow titles to be added, which were shot on a high contrast background by another live camera. Keys as we know them were a later development, and external keys had to wait for the development of the character generator.

Other “special effects,” wipes, modulated wipes, chromakey and digital video effects came in successive products from companies that included RCA, AMPEX, Duca-Richardson, Vital Electronics, CDL and Grass Valley Group. Are you ancient enough to remember the introduction of the Squeezoom by Vital in the 1970s? Four channels took a full rack and had more wire wrap than a mainframe, and needed a full-time babysitter to keep it operating. By that point, it was clear that digital processing and image transform theory would ultimately lead to digital switchers, with Grass Valley Group introducing the Kadenza in 1988.

In the 27 years since the introduction of digital switchers, we have indeed seen an enormous change in both hardware and software technology. This has given us marvelous tools to complete live programming and sophisticated post-production.

Today we are in a significant revolution in the technology with new and old players moving toward products that bridge the divide between the era of 525 and 625 television to the future in HDTV. For decades, manufacturers built two models for 525 and 625, and later models that could be switched between the two, and later still digital switchers that adapted to both 525 and 625 variants of SMPTE 259M switchers.

Those who implemented systems in the late 1980s might have even chosen parallel input video switchers, which used SMPTE 125M for interconnection. But now we have an array of options that will map nicely into a business increasingly concerned about ROI and depreciation, and products extensible into an unknown evolutionary facility future.

Oddly, the need to have scalar chips in consumer electronics, like set-top boxes and plasma displays, is an important part of the change we are in. You may not realize it, but there is a full HDTV format converter in every plasma display, which takes the output of the set-top and scales it to the resolution and aspect ratio of the display. Putting that capability into the input processing of a switcher can allow format-agile switching technology for the first time.

A second enabler are professional chip sets, which allow both SMPTE 292 and SMPTE 259 signals to hit one input processor. The two combined allow the video switcher to adapt to all standards a manufacturer wishes to support. That can take the form of a software switch that flips the entire system to a new standard, or, in the case of some manufacturers, to permit simultaneous SD and HD inputs, both usable in the cut program at the same time. Snell & Wilcox has enabled the use of both SD and HD in the same switcher at the same time, considerably raising the bar and encouraging others to follow suit in the future.

Output/input capability

That is not to say that there are no differences between SD and HD switchers. Electrically, it is clear that a signal with roughly four times as many pixels per second will require more memory and a faster processor to do the calculations required. It also is true, however, that Moore's Law points out that processor speed and power continue to increase, making the calculations a video switcher does ever easier to achieve at any specific cost. Balancing that is the inexorable increase in demands for production power. Six or more channels of internal full-featured digital video effects are not at all uncommon now, and still stores, motion video clip stores and other advanced features are becoming standard in the equipped configurations generally ordered.

One common feature of digital switchers that was not possible at a reasonable cost inside an analog switcher is programmable outputs. Installing a three mix effects switcher a decade ago might have meant connecting one to two dozen primary outputs of the electronics frame (program, preview, preset, ME previews, DSK previews, etc.). Even with aux outputs, the total would be unlikely to get above 30. A digital switcher today might have 48 or more outputs, each of which can be selected in software to follow any signal in the switcher. Need 10 copies of program? Not a problem, and you would still have 38 more choices.

Additional features

Mirroring the output capability of modern switchers is greatly expanded input capability. With up to 90 direct inputs, modern switchers can eliminate the need to have routing on inputs to the system, reducing system cost and complexity. Keep in mind that key and fill signals from character generators and graphics systems (still and clip stores) take up two spigots though, making 90 seem a bit less over the top. Still, in very large network installations, or those with multiple control rooms, which must flexibly access large bases of signals, routing might still be needed.

Operator interface is one part of a modern switcher that is not much different in concept from that of a decade ago. Large and complex panels are needed to allow operators to access complex features. However, modern switchers are highly customizable, and some manufacturers have begun to use buttons with LCD legends inside the actual button. This allows memory recall of setups without confusing the operator.

Other features that are highly desirable and new in advanced production switchers include the ability to copy settings from one place on the work surface to another. One can even move entire MEs to other sets of buttons, or address a three ME switcher with two MEs' worth of buttons.

Finally, the interface now includes almost universally a touch-screen with rich sets of configuration and operations menus. They allow control of other devices, display of still store operations on a GUI associated with that feature and many other new features that TDs would have killed for a few years ago.

In the end, a modern switcher can be flexible, grow and evolve with the facility during the HDTV transition, and provide highly advanced features. This kind of protection of investment is certainly worth it to facility owners and producers alike.


John Luff is senior vice president of business development for AZCAR.

Send questions and comments to: john_luff@primediabusiness.com.



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