Pro AV Logo Originally published as a Consultant's Connection
column in Pro AV Magazine
  March 2003

DSP – Desperately Seeking Paradise

While we pursue the power and flexibility that DSP and network-based AV offer, we will be challenged to change the way we think about our work and our roles as consultants and integrators.

By Tim Cape, CTS-D

Audio is always ahead of video it seems—at least those of us who started out in audio like to think so. Technologically, though, it’s true. It was audio that first moved into the digital realm and put ones and zeros in the mainstream of the consumer and the pro AV world. It was digital audio on tape before digital video. It was CDs before DVDs. It was WAV files before AVI files. It was Peavey Media Matrix before, well…we’ll see what’s next there.

Video has the bandwidth handicap, so it’s only natural that the relatively narrow bandwidth of audio leads the way onto LANs and DSP (Digital Signal Processing) chips.

Though audio moved first into the digital realm followed by video, the digital disparity between the two has been lessening every year. But we don’t yet have the configurable video DSP box that lets us design and install a video system with a mouse as we do with the audio DSP devices on the market today. But it will happen, and probably soon.

As with many of the transitions we have to make in our industry, the evolution of audio systems from racks of dedicated single-purpose analog electronics to a few multipurpose DSP boxes isn’t that easy. The promise is paradise in heaven, but the reality can be hell.

It’s always something

First there’s the hardware. This is all new stuff—not your father’s tubes and transistors—and not always designed by venerable audio engineers. Then there’s the software, and the firmware, and the serial port and the USB-to-serial adapter we have to use while we wait for the Ethernet port to be provided. Where’s the driver for that, anyway? And then there’s the LAN to deal with. What happened to the days when a tweaker, a little test gear and a brain was all we needed to setup and run an audio system? The only digits we needed were the ones on our hands, and we could keep track of those most of the time.

That said, I do love to work with new technologies and attempt to realize the promise of software and silicon that can make us feel like we’re the Jetsons on Planet AV—paradise for some. But I do remember those ghosts of systems past that allow me to appreciate both the beauty of the DSP dream and the frustration of living on the sometimes-bleeding edge of an emerging technology. So what are the practical implications of all of this?

First of all, we have to remember that DSP does not an audio expert make. We have to know audio inside and out to do well with DSP (or any other audio tool). But using DSP, we have to learn a new way of troubleshooting because the things that can go wrong are multiplied relative to older systems. There are lots of potential obstacles just to get started: What version of Windows am I using? Do I have the right driver for my serial interface? Have I got the current version of the manufacturer’s software to upload and manipulate the configuration file? Do I have to turn the units on and off together and recite an incantation to keep the gods of DSP happy?

OK, enough ranting. That’s the hell. Is it worth it? For starters, it’s great to have the option to reconfigure an audio system on the fly and even add a piece or two of virtual gear with no wiring or change orders required. I like having less wiring to check when I go to a jobsite since most of the cabling is now virtual and I can check them out in the comfort of my office or my front porch by looking at the systems setup file. I like having an echo canceller on every mic channel in a large videoconferencing system. There are lots of benefits to offset the inevitable aggravation of a developing technology.

Blurring the Lines

One of the most intriguing outcomes of using DSP in our audio work and networking in our control systems today (and without doubt DSP in video systems of the future) is that it blurs the lines between consultant and integrator. When a consultant designs a system that is DSP-based, the block diagram for the hardware wiring may look very simple compared to the virtual system inside the DSP box. Is it the responsibility of the integrator or the consultant to provide the block diagram between the DSP inputs and outputs? It seems clear to me that on a consultant-designed project, the consultant should provide the design inside as well as outside the box. This is how it would work when everything was its own rack-mounted device, and it’s the configuration of the boxes, virtual or otherwise, that constitutes the system’s design.

The crossover, so to speak, occurs when the consultant-designed DSP-centric system is installed by the integrator. The virtual system may be very complex, the result of a year or two of thought and interaction with the client. What often happens is that the field installers aren’t always up to speed with either the DSP technology, the specific manufacturer’s current software or the minutia of the system’s intended operation. Therefore, the consultant is the one who will ultimately upload the file, as well as tweak it to suit the conditions of the installation. In this case, the consultant just installed a major part of the system.

Beyond that, what happens when the system moves into the post-commissioning phase and the installation personnel are scattered to the next job and the integrator’s service tech gets a call from the system owner? He or she often doesn’t have the tools or the background knowledge of the system to adequately troubleshoot a complex DSP-based problem. Guess who gets the next call? The consultant. Now we’re in the service business, too. But this doesn’t just happen in a consultant-led design scenario.

In an integrator-driven design-build project, it’s likely to be the integrator’s system designer loading the DSP configuration and who ends up as a part-time service tech on the job. Sometimes the service techs don’t even have laptop computers, the needed software, adapter or training to even get into the system. It’s a problem that we all have to deal with as these technologies move ahead faster than much of the AV workforce can learn about it.

While we pursue the power and flexibility that DSP and network-based AV offer, we will be challenged to change the way we think about our work and our roles as consultants and integrators. The need for more educated and experienced AV professionals will only increase, but with the help of organizations like the National Systems Contractors Association (NSCA) and the International Communications Industries Association (ICIA) that are working to meet this need, paradise promised won’t be paradise lost.

 

 

 
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