AV Design in the Digital Age

Maybe our digital future is closer than we thought.

By Tim Cape, CTS-D

The Digital Age. How often have we heard that phrase? For most of us, quite often. And cliché or not, we keep hearing it for good reason.

Although many pro AV installations still run analog audio, digital is the norm for much of the audio processing and signal transport. Video is also coming along mostly in processing boxes, but as we move to more server-based media, we get closer to the allnetworked AV system model. In the meantime, DSP has become commonplace in the AV industry, and its effect on our world is an indication of how truly “digital” we are today.

The DSP Symposium

Based on a suggestion at the International Communications Industries Association’s (ICIA) Independent Consultants in AV Technologies (ICAT) council meeting last year, the free “DSP Symposium” forum was launched at this year’s InfoComm. I don’t know how many signed up for the event, but unfortunately few attended — probably because the term DSP just isn’t as interesting as it used to be. Nonetheless, there was a fantastic (and large) panel of 11 AV professionals that encompassed integrators, consultants, manufacturers, and programmers. The audience, however, only outnumbered the panel by one.

To say the least, I was disappointed in the turnout, and I wasn’t even part of the panel. But the quality of the discussion was superb and enlightening, and it’s too bad that more people weren’t there to experience it. Perhaps next year these kinds of sessions can be captured for later viewing on the Web, regardless of attendance. In the meantime, you’ll just have to hear about it from those who attended.

The idea behind the Symposium was to highlight the impact and peculiarities of DSP as it exists today within pro AV. Yet, it soon became apparent that DSP wasn’t really the subject to be discussed. In years past, DSP itself was the issue. It was new; the software to setup and operate the devices was unreliable and buggy; and it was a painful adjustment for many of us. But these subjects are now mostly old news. DSP still isn’t perfect, but it’s become a much more common and reliable tool like the pure analog hardware devices that were available in the past.

But once we get over the newness of DSP, we’re back to the same old issues of AV design. What are the end-users’ needs? How can our audio and visual designs service them? What electronic devices do we need to accomplish the tasks? How do we get signals from point A to points B through Z?

Most of the tools we use today — virtual or not — are the same as they have been for a long time: mixers, equalizers, delays, switchers, routers, echo cancellers, video processors, codecs, and all of the other AV devices we have available. It’s just that some of them are now consolidated inside a single digital hardware box rather than a rack full of analog devices.

Focusing on control

As the forum discussion progressed, there was more and more talk about interfaces and control rather than DSP. In some ways, DSP is now a commodity — it’s not about the processing power anymore. (Maybe it never was.)

Now it’s the interface to the processing power that’s the “value-added” piece of the technology. All DSP devices save on hardware space. It’s how they’re setup, accessed, and controlled that’s the differentiator.

One key problem (as well as advantage) with DSP is the size of the box. We can collapse what used to be dozens of AV hardware devices into one or two rack units. For space saving concerns, this is great. But for interface and control, it’s a problem. First there’s the physical interface and monitoring. For example, if we’re creating 25 devices inside of a single rack space box, we have only about 0.2 square feet for a physical interface on the front of the DSP box, compared to maybe 8 square feet of faceplate user interface area using all analog devices. Knobs, switches, and buttons just don’t do it anymore, so we have to go to software.

But even in software we somehow still have to fit 8 square feet of interface into about 1 or 2 square feet at most. We also have to add in management of the virtual connectors that would be on the physical rear panel of the analog AV devices. And then there are all the things that get thrown into the software interface just because we can, such as more metering, extra inputs, more labeling, and more low-level parametersettings than we ever had with pure analog devices.

Thinking inside the box

To do the job we’re supposed to do during design, we need to take all of this information and produce a system design that allows someone to build the AV system. This means — as it did years ago — that we need to lay out the system configuration from every system input to every system output. We also need to design how the endusers will control and operate the system, including the user interface design.

Part of this means that drawings should be created to illustrate how all of the devices interconnect. Before the days of DSP, this would be lines on paper showing how all of the analog hardware devices were connected. Today it means the same thing except that some of the devices are in software. For AV designers to do their jobs, they can’t stop at the hardware anymore. We have to think inside the box for a change, and finish designing the system inside the virtual device that we originally started to design outside of it.

Some designers find it all too convenient to simply draw the lines for the DSP device’s hardware connections and leave it up to the installer to figure out the rest. But this ultimately creates a host of problems with design responsibility and control system coordination. AV designers —whether consultant or integrator — should complete the system design both inside and outside the box.

It’s all about the bitstreams

Besides the plethora of network-based AV options, this design inside of the DSP device is the primary indicator that the AV industry is transitioning from a hardware industry to a software and data networking industry — a point well made at the Symposium. And the transition isn’t easy for some.

AV hardware manufacturers are learning to be software design and data networking companies. AV integrators have to transition their staffs and operating budgets into more educated, higher-paid, and better-equipped personnel. Field techs that were good with a screw driver and soldering iron now have to be good with laptops, RS232, TCP/ IP, and a variety of AV manufacturer’s software, too.

AV consultants now have to be user interface designers, network designers, and DSP software experts. System owners are learning about all of these things as well as other formerly remote subjects such as digital asset management. And now the entire AV industry — including the manufacturers, consultants, integrators, and system owners — are learning what intellectual property means.

When we stop for a moment and look around, we can see that this is the dawning or perhaps even the late morning of the truly digital age for pro AV. So it’s time to wake up and smell the bitstreams, because that’s what the electronic side of our present and future business is all about.

And you know what happens when you hit the “snooze” button…

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