show control

Show control is the use of automation technology to link together and operate multiple entertainment control systems in a coordinated manner. It is distinguished from an entertainment control system, which is specific to a single theatrical department, system or effect, one which coordinates elements within a single entertainment discipline such as lighting, sound, video, rigging, or pyrotechnics. A typical entertainment control system would be a lighting control console. An example of show control would be linking a video segment with a number of lighting cues, or having a sound cue trigger animatronic movements, or all of these combined. Shows with or without live actors can almost invariably incorporate entertainment control technology and usually benefit from show control to operate these subsystems independently, simultaneously, or in rapid succession.

Show control networks

Show control networks have largely supplanted older show control typologies. This is primarily due to the maturation of the larger information technology (IT) computing industry, which, due to its scale and dominance, has produced standards, equipment and software which is less expensive than older show control equipment and methodologies and increasingly more reliable and usable in entertainment applications.

Modern systems are increasingly based upon Ethernet networking. Most manufacturers of entertainment control equipment now include Ethernet ports on their equipment. Ethernet was originally disqualified from consideration for show control because it was slow, non-deterministic, and lacked sufficient bandwidth to handle certain show control functions. These early objections have been overcome with the use of full-duplex switched Ethernet running at 1000BASE-T speeds on a dedicated local area network (LAN).

MIDI Show Control

The MIDI Show Control (MSC) standard is an open, industry-wide international communications protocol through which all types of show devices can communicate. MIDI generally is a simplex asynchronous serial data transmission standard with the circuit being an opto-isolated current loop type. MIDI, an acronym for Musical Instrument Digital Interface, was originally designed in the early 1980s as a means of controlling multiple keyboard synthesizers from different manufacturers. Beginning in 1989, a group of interested theatre professionals headed by Charlie Richmond of Richmond Sound Design in Vancouver British Columbia began discussions on the USITT MIDI Forum Callboard Network. This forum included developers and designers from the theatre sound and lighting industry from around the world. They created the MSC standard between January and September, 1990. It was ratified by the MIDI Manufacturers Association (MMA) in January, 1991, and the Japan MIDI Standards Committee (JMSC) later that year, as an extension of the standard MIDI specification. It became an accepted standard in August, 1991. The first show to fully utilize the MSC specification was the Magic Kingdom Parade at Walt Disney World's Magic Kingdom in September, 1991.

DMX512

USITT DMX512-A is the current de facto standard for lighting control systems. It is an asynchronous serial data transmission standard commonly found as a control scheme between computerized lighting consoles and connected dimmers, moving light fixtures, color changers including LED fixtures, and certain effects (fog, strobes) which are usually operated by the electrical (lighting) department in theatres.

DMX512 was originally launched by USITT in 1986. It was updated in 1990 to USITT DMX512/1990. In 1998, the maintenance of the standard was transferred to the Entertainment Services and Technology Association (ESTA). ESTA revised it, and it was accepted by the American National Standards Institute (ANSI) in November 2004 as "Entertainment Technology—USITT DMX512-A—Asynchronous Serial Digital Data Transmission Standard for Controlling Lighting Equipment and Accessories". In 2011, ESTA merged with the Professional Lighting and Sound Association (PLASA), which now manages the standard. The standard is now called "E1.11 – 2008, USITT DMX512-A".

At one time, DMX was put forth as a possible show control standard, mainly by the manufacturers of lighting control consoles, but this idea was never widely adopted, due to the speed and network traffic limitations of DMX for show control applications.

Dante, CobraNet, and others

Audio systems have also benefited from digital networking technology. Dante (Digital Audio Network Through Ethernet) is one of the most technically advanced means of routing high quality audio over an Ethernet network. It is a proprietary audio over Ethernet scheme using layer 3 packets to distribute uncompressed, multi-channel, low-latency digital audio in professional installations. Dante was developed by Audinate of Australia in 2006, and has since been licensed to a number of hardware manufacturers worldwide. It requires a combination of hardware and software to operate. Similar layer 3 products are RAVENNA (an open standard developed by ALC NetworX GmbH., Germany), Livewire by Axia Audio (a division of Telos Systems), Q-LAN by QSC Audio Products and WheatNet-IP by Wheatstone, most of them interoperable by conforming to AES67.

CobraNet, although an older proprietary standard dating from 1996, still enjoys a large base of installations. It is regarded as the first commercially successful implementation of networked digital audio. It utilizes layer 2 packets to distribute uncompressed multi-channel digital audio in professional installations. Its first theme park use was to distribute background music (BGM) in Disney's Animal Kingdom park. It also requires a combination of hardware and software to operate, and has been licensed to multiple manufacturers.

Interest in transferring audio over Ethernet arose about the same time the audio industry was making increasing use of digital signal processing (DSP). Sound engineers had been altering audio through various analog means for many years, but with the advent of fast, low-latency digital chips, audio signal processing moved rapidly into the digital domain.

Time code

Some types of attractions operated by show control are nearly completely based upon clock-driven timing. These are most commonly found in theme parks in semi-automated attractions which are repetitious and not usually subject to variation. Certain ride systems, once manually started or dispatched, may run entirely on time code nowadays. Certain shows, such as