Did You Say Network?
by Michael Karagosian
©2001 MKPE Consulting All rights reserved worldwide
Published in the Aug 2001 issue of System Contractor News
HAL. Where are you?
It's 2001. If Arthur C. Clarke had anything to say about it, we'd be having conversations with our systems today, rather than conversations about them. And while Sir Clarke didn't discuss the concept of networks in his writings, surely HAL knew all about them. But could HAL have possibly appreciated the Internet browser? Maybe we just took a wrong turn somewhere.
Back in the early '90's, the idea of computer control was a big topic. The visionaries of the time wanted to control systems using peer-to-peer networks. The idea of a publicly-owned, internationally standard, control network was the holy grail of the time.
Unfortunately, we didn't have a common network back then upon which to build. In the early '90's, an Ethernet port cost in the neighborhood of $100, which translated to $300 or more in actual increase in product cost. And without the cost benefits of wide market distribution, the financial barrier to entry for other network technologies was simply too much for most companies.
But today we have a common network, and the financial barrier to entry is smaller than ever. This network, of course, is the IP (internet protocol) network. We use it to communicate between companies, to connect corporate offices with one another, to communicate among our fellow workers, and so on. With the ubiquity of the IP network (please note the use of the word ubiquitous, a must-have for any high technology article, and the use of which should score extra frequent flier miles with my favorite airline), you'd think we'd see it in every product in every system.
But possibly it's not the standard I describe? IEEE-1394 has proven itself in the semi-pro studio market, but has no relationship to Ethernet . And then there's Cobranet, which can't run on an IP network, either. Hmmm. Maybe HAL knew what it was doing. We humans can't be counted on to get it right.
Ignoring HAL for the moment, let's take a look at the various ways in which networks are used today.
The ubiquity (there's that word again) of HTML, Java, and the Internet browser has paved the way for their use in many of our products. It works like this. Plug your computer network into the Ethernet port of the product, type the product IP address into your internet browser, and you'll see a web page, complete with setup controls. Instant remote control, from anywhere in the world. (Get familiar with your network's security layer, however, before you plug it into the great beyond of the www.)
This method can provide remote control with little effort, taking advantage of readily-available data networks, as well as the world-wide-web. But it only offers a fancier form of master-slave control. One browser instance, one product. While multiple browsers can be used, they often are not synchronized with one another, so that changing a level setting on one browser does not necessarily change the value shown on other computer screens. Controlling multiple products can be difficult as well, as each box requires a unique page. However, for some products, such as the Digital Video Machines from Alcorn McBride, and Peavey's MediaMatrix, this technique provides very useful remote control of system setup parameters.
A more sophisticated way of implementing browser-based controls requires a more sophisticated user. Manufacturers that provide software components, such as Active-X Controls, allow users to implement both Visual Basic programs and Internet Explorer pages themselves. This can provide capable users with the ability to create a GUI that is designed for the application, as well as control multiple products with a single screen. This is the heart of the control method employed by QSControl, QSC's amplifier control technology, and also available from Rane for their computer-controlled products.
Components have the advantage of hiding the complexity of the underlying control protocol from the system integrator while enabling them to design their own control screens. A more direct protocol-driven control method can be useful for manufacturers who wish to sell or license their own ready-made control software. The protocol of choice these days is SNMP, Simple Network Management Protocol. A publicly-owned client-server protocol, SNMP has been used extensively by the makers of computer and network equipment for many years. While first introduced in the audio world for Cobranet interfaces, SNMP control of amplifiers has also been introduced by Crown Audio.
Certainly, any equipment that is controlled by means of a computer screen can have that screen mirrored on a remote computer using programs such as Symantec's PC Anywhere. As simple as this sounds, it has the advantage of allowing virtual many-to-one type of control. Since all viewers are literally viewing the same screen, all users will be updated whenever a change is made, regardless of the source of that change. Proprietary methods also exist that provide efficient mirrored remote control for specific products, such as the RAMM program included with MediaMatrix.
Back to our holy grail of the '90's, though, none of the solutions mentioned so far provide peer-to-peer networked control. A peer-to-peer control method requires multiple controllers to talk to one-another without the need for a central controller. For many applications, peer-to-peer control can be ideal, eliminating complex centralized control systems, and eliminating the system's sensitivity to single-point failure. Opening a room divider in the hall of a convention center, for instance, could automatically join the speaker systems, without the need for a central controller dictating the result. To make this work, every piece of affected equipment must be on the network, and each piece of equipment must understand what to do when the network announces a particular event.
Echelon's LonWorks control system has been adopted by several audio equipment manufacturers, including Renkus-Heinz and Meyer Sound. While not an IP-based control method, LonWorks offers peer-to-peer control. Users can either talk directly to a device through a central controller, or they can allow devices to respond to one-another's state. For instance, if it's desirable for Amp B to turn on and off with Amp A, then Amp B only needs to be programmed to follow the state of Amp A. Likewise, Amp A only needs to announce its state on the network. The system thus becomes easily scalable, as more amps can be added without any change in the programs of Amp A or Amp B. To be fair in my description of LonWorks, the LonTalk protocol can be routed over IP networks, and the Cisco-certified iLON-1000 can not only provide the routing service, but also provides secure HTML web page control of the LonWorks network it serves.
Part of our 90's search for the holy grail of networks was audio delivery. Today we have Cobranet, now owned by Cirrus Logic, as a method to communicate audio over Ethernet networks. We also have IEEE-1394, for which Cirrus Logic is also developing the Digital Harmony 1394 chip. Cobranet, however, is MAC based (a low level protocol), not IP-based, so while network traffic can be directed with off-the-shelf network switchers, it cannot ship audio over the Internet. And 1394/1394a, while ideal for the networking of semi-pro audio gear and consumer home entertainment systems, suffers from distance limitation and inoperability with IP networks. 1394b, though, is right around the corner, and will overcome both speed and distance problems, guaranteeing it a place in the A/V world.
As the role of DSP-based audio systems extends into paging and voice conferencing applications, audio-over-IP will be in demand. We've done the multimedia conference room. Now it's time for networking conference rooms and paging systems with branch offices around the world. What protocols will these systems rely upon? The same protocols used in voice-over-IP, or VOIP. At the core of VOIP are the RTP and RTCP protocols (Real-time Transport Protocol and Real Time Control Protocol), which can be used with professional digital audio sampling rates and word lengths. And they're publicly owned. and ubiquitous. So where are the products?
Maybe we need to talk to HAL about this.