Fundamental to any control room is a method of monitoring the audio and video that is being assembled in production or air operations. Though the requirements of those environments are not identical, we sometimes attempt to shoehorn both into a single system. In the recent past, monitor walls were built up using metal racks and discrete monochrome and color monitors, with speakers, clocks and the odd computer display added where applicable. In some complex facilities managing large numbers of incoming and outgoing feeds, like a network news or sports operation, the number of discrete devices can grow quite large.
Such systems have worked well, however. There was great flexibility to design cost-effective monitoring by applying cost/benefit analysis to the selection of each monitoring device. Feeds for which only signal presence was important did not need the expense of a color monitor or speaker, and monochrome 9in monitors were popular. When audio levels or critical video performance evaluation are required, a switched system, close to the operator, allows for detailed analysis or quality checking. This is particularly effective from the operator's perspective.
One might ask why this has changed, as it has, in fundamental ways. The factors are quite obvious, not the least of which is the rather rapid disappearance of discrete, low-cost, small monitors. CRT monitors are vanishing rapidly, reducing available options. Secondly, the power consumption of multiple monitors is at least additive, and considering the conversion loss in each power supply, it is likely a drain on power and air conditioning systems.
Looking at a mechanical model, a “conventional” monitor wall is constrained by the metal that supports it. It is space-inefficient, heavy and not easily adapted to special use cases that require monitors that don't fit in a rigid 19in rack structure. I built a “nonconventional” monitor wall in a mobile unit that was used for HD delivery of NFL games that broke ground as the first entirely flat-panel-based monitor wall. Had we been constrained by the 19in limit, the monitor wall would have contained fewer monitors. The system mounted the monitors inches from the outside wall with no lost space between displays. It also allowed us to use large monitors for program and preset, and still group the 17in 16:9 flat-panel displays efficiently around the outside of the large monitors.
Though the ability to pick individual monitors was once appealing, overall, the constraints placed on monitor wall construction have become a burden on both the design and operation of television facilities.
Happily, two developments came along in the last decade that together have fundamentally changed how monitoring is done. Individually, neither would have solved the problems older approaches could not. Flat-panel widescreen monitors came from consumer electronics initiatives, not from purpose-built HD displays for broadcasters. Initially, plasma, and later LCD and other technologies, allowed relatively low power consumption compared to similarly sized CRT monitors. But they didn't fit well in the 19in structure we were constrained by, and they were too large to allow single-source monitoring of a large number of sources.
The other development that changed our collective lives was not what you might assume. It was the development of scaling engines, in silicon, that were created to allow flat-panel monitors to accept multiple scanning standards and spurred the ability of new composite devices to combine many signals into one output. These scaling engines became monitor wall processors. Over time, the capabilities of monitor wall systems grew to embrace all of the devices we put in monitor walls in discrete form, including clocks, audio metering, closed caption decoders, etc.
The idea of monitor wall processors preceded practical HD/SD systems by most of a decade. However, they were initially limited to a fixed layout of usually 16 inputs. Since they were based on complex technology, not silicon solutions, they were also expensive. Thus, though they were ground-breaking in many ways, they had no impact. It took the additional development of silicon scaling engines to facilitate a practical multi-image monitor processor.
This is no longer a surprising confluence of factors, for it arises out of consumer electronics momentum. Flat panels and the technology of monitor walls have evolved from systems outside the professional domain. Other professional products have come from similar synergy, like DV-based recorders that came from the development of consumer VCRs, which by the way were largely a market flop. Once the research has been paid for, our professional electronics manufacturers are happy to co-opt new technology into creative systems for professional system problems. Personally, I hope we never stop doing this.
There are, however, problems that arise from using this approach. Perhaps the most obvious is that using consumer display technology that has the same resolution as studio signals seems like the perfect marriage of convenience and necessity, but it binds us to multiple windows of lower resolution displayed on a single display. The filtering used in multi-image processors is good these days, but of necessity the pictures are degraded.
We can hope that processing systems will adopt higher resolution outputs soon, because consumer 4K displays are beginning to show up. For those concerned about preserving quality, it would be nice to get back to full resolution, or close at least. This would not be inexpensive, but the display cards in computers already have the ability to feed higher resolution displays that have been available from a number of manufacturers for years. It is worth noting that even tablet computers now have higher than HD resolution, and higher resolution (and frame rate) acquisition and processing is now commercially possible. It won't be long before HD is the new SD. Remember, at one time the British 405-line standard was considered HD.
Finally, a word of caution: When building a wall of displays of one type, one has to hope that for a reasonable number of years all of the displays age similarly and that should replacement of one become necessary, a replacement of similar dimensions and performance will be available. With our reliance on CE manufacturers for these critical pieces of our facilities, it is a fervent hope, but one without guarantees.
John Luff is a television technology consultant.
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