Glossary of Technical Theatre Terms – Multimedia

Stands for Automated Dialogue Replacement. Also known as "looping" this is the post-production process on a film / TV shoot where actors re-record their lines after original filming, either because the original production sound was not up to standard or due to external factors (aircraft noise in a period piece) which weren't noticed at the time of filming.

Originally Audio-Animatronic™, this term describes a robotic figure, particularly in a theme park environment or on a movie set, which is able to repeat a limited range of pre-programmed functions, typically in synchronisation with a pre-recorded soundtrack. The term now describes a character controlled either electronically by radio remote control, or by cable/lever controls.

A ratio which defines the relationship between the height and width of a movie frame.
The Academy ratio is 1:1.375 (i.e. if the height of the image is 1 unit, the width will be 1.375 units).
Silent movies were shot in 1:1.33.
Cinemascope is 1:2.35.
A traditional TV picture is known as 4:3 (width:height, which can be expressed as 1.33:1). A widescreen TV is 16:9. (or 1.77:1)

Short for Audio-Visual, referring to projected or screened video or textual material.


VGA to Cat 5 Balun (PC side) - MuxLab 500040 A device which changes an audio or video signal from unbalanced wiring to balanced (or vice versa). The name is derived from BALanced / UNbalanced.
The term is commonly seen now for devices that adapt an analogue audio or video signal so that it can travel long distances over standard wiring (such as CAT5).

Professional video tape format developed by Sony (short for Betacam SP). Beta SP is broadcast-quality and is a relative of Sony's failed Betamax domestic standard.

A range of half-inch professional videocassette products developed by Sony in 1982. Consists of Analogue and Digital formats.
Wikipedia entry

(Trade Name) Consumer-level analog videocassette magnetic tape recording format developed by Sony, released on May 10, 1975
Wikipedia entry

BNC Connectors on black coaxial cable (from Coaxial connector used for carrying a composite video signal or radio frequency signal. BNC stands for Bayonet Neill Concelman - after original inventors Carl Concelman and Paul Neill who developed the connector in the late 1940s. BNC is also thought to stand for 'Bayonet Nut Connector'.
See also TNC.

A measure of the amount of light produced by a display screen, projector or light source.
Data projector brightness is measured in lumens. A lumen is a measure of the brightness of a light source.
One lux is one lumen per square meter. One lumen is one candela per square radian (to measure the light travelling outwards from a light source).
Cinema screen brightness is measured in nits. A nit is unit of visible-light intensity, commonly used to specify the brightness of a cathode ray tube or liquid crystal display computer display. One nit is equivalent to one candela per square metre.

Circular slide magazine; also refers to a 35mm slide projector using this type of magazine (Kodak trade name). See PROJECTION.

Acronym for Computer Generated Imagery. Any images or special effects sequence in a film / video / multimedia presentation which is created in computer software such as After Effects, or any motion graphics or special effects compositing software. 

Shortened to Chroma or C. The signal in component video systems that contains the colour information for the picture. The monochrome part of the picture is luma or luminance.

Unterminated 75 Ohm Coaxial Cable (RS Components) A shielded copper cable used for satellite TV, analogue TV, video and some digital connections.
Sometimes shortened to 'Coax cable', it consists of an inner solid copper conductor surrounded by a plastic insulator, which is wrapped with a braided copper screen, with an outer protective sheath.
There are different connectors used for coaxial cable, including RF connector, threaded F type satellite TV connectors, or locking BNC connectors. There are also different types of coaxial cable, for different purposes, identified by their electrical impedance. 75 Ohm (written as 75Ω) cable is used for video, while 50 Ohm (50Ω) is used for data and radio signals.

Composite video is the format of an analog television (picture only) signal produced by video cameras (camcorder or CCTV). Connectors used are either BNC (pro / semi-pro) or RCA/phono (domestic / semi-pro). A yellow-coloured RCA/phono socket is used for composite video output or input.
Sometimes shortened to CV. 
Wikipedia entry

1) Digital projectors have a contrast ratio, which is a measurement of how much brighter the white image is than the black image. A contrast ratio of 1000:1, for example, will result in a muddy grey colour instead of a sharp black. A higher contrast ratio will result in a darker black - a DLP projector uses mirrors to create the image, and can result in very high contrast ratios and very dark blacks - this means if the projector is showing a blank / black screen, the light from it is hardly seen. A lower contrast ratio will result in a grey rectangle being projected at all times.
High quality cinema projectors have a contrast ratio which is measured more accurately (the ANSI Contrast Ratio) which might be up to 5000:1 and is measured under very specific conditions. 
2) In photography terms, the contrast is the difference between the darkest and lightest parts of the image. 
Contrast Ratio measurement

Cathode Ray Tube. Refers to a TV/monitor using a traditional tube (rather than a TFT / flat design)

A list of sound, lighting, automation, scene change, video, followspot (etc) cues in order of their appearance in the show. Each cue is given a unique number, and the list includes a brief description of what it does (e.g. for Lighting: Blackout, Dim Downstage Wash, Red Spot Upstage; for Sound: Preshow Music, Fade Out, Snap Music to Quiet etc. )
Cue is often abbreviated to 'Q". 
Also known as a Plot Sheet. 

As prices are dropping, the use of a data projector connected to a laptop or PC/Mac is within the budget of almost every performance.
See link below for more information. 
Known in parts of Europe as a BEAMER.
See Multimedia Projection for Drama for more information.

Interface connected between two or more slide projectors and a tape player. Synchronisation signals recorded onto the tape are detected by the dissolve unit and fade up the lamp in one slide projector while changing the slide in the other, and then vice versa, producing a dipless crossfade between the two images.

DLP / D.L.P.
Digital Light Processing. Digital technology licenced from Texas Instruments which enables video projectors to deliver a brighter, sharper, more detailed digital image. The first DLP projectors arrived in 1996.
DLP technology

Dots per inch. A measure of the resolution of a printed or computer image.

Digital Video. Professional video format.


Digital Versatile Disc.

Digital Visual Interface. New interface connection standard between computer and display device.
PDF article about DVI

Acronym for Extended Display Identification Data. This data is exchanged between monitor and media server or laptop, and enables the device producing video content to match the capabiliites of the output device, and also ensures the monitor is identified in the software accurately. The protocol was first introduced in 1994, and was revised in 2000 to be E-EDID (Enhanced Extended Display Identification Data). 

1) Apple video editing software (originally developed by Macromedia). 
2) The final (finished) edit of a film / TV programme, which the director / producer has approved. 

FireWire is another name for IEEE 1394, a high speed data transmission protocol developed in the mid 1990s by Apple which is used extensively on digital video and audio equipment and on PCs.
The FireWire 800 (IEEE 1394b) operates at 800Mb per second and can transmit data over 100m cables.
Apple stopped using Firewire on Macs in 2012, and have replaced it with Thunderbolt and/or USB 3.0.

A measurement of the luminance (brightness) of an image on a projection screen, used in the motion picture industry. The unit is also used in military applications for the brightness of illuminated display panels. 
The unit is defined as 0.3183 candela per square foot (or 3.426 candela per square metre, a unit sometimes known as nit). 
The Society of Motion Picture and Television Engineers (SMPTE) recommended a screen luminance of 16 foot-lamberts for a commercial movie theater / cinema, when measured 'open gate' (with no film in an analogue projector). This equates to 55 candela per square metre (55 nits). 
What Are Foot-Lamberts at

Frames per second. The UK standard is 24 fps for film, and 25 fps for television. In the USA, the TV standard is 30 fps.

1) (especially TV and Film) Jargon for a replacement lamp.
2) The glass part of a lamp.
3) The Globe Theatre in London.
See also BUBBLE, LAMP.

Widescreen (16:9) high-resolution digital TV format.
HD-TV basics website

HDBaseT is a standard for connection and transmission of high-definition video, audio and control / data signals using a Cat6 cable. The standard was launched in 2010, and can transmit up to 100m using good quality cable.
HDBaseT website

HDMI Cable (Canford Audio, UK) High Definition Multimedia Interface. HDMI is a proprietary audio/video interface for transferring uncompressed digital video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to a compatible computer monitor, video projector, digital television, or digital audio device.
Wikipedia entry

Camcorder video format designed by Sony as a follow on to its lower-quality Video 8. Uses 8mm-wide tape.

A trademarked system for achieving high-brightness 'holographic' projection effects. Patented by Stuart Warren-Hill. 
HoloGauze Patent, 2017

(Film Industry) A scene or sequence has finished being filmed. (e.g. "Thanks everybody - that scene is in the can now"). Refers to a roll of film being taken out of a movie camera and put into a metal film can to be taken for processing.

1) A piece of performance or writing which falls between genres and cannot easily be categorised in familiar ways. 
2) In TV programming, an extra programme or introductory sequence inserted between the main programmes.

A function available on data projectors which allows the selective stretching of the horizontal component of the projected image so that it appears to be rectangular when projected from an angle above or below the projection surface. More advanced (expensive) projectors can also keystone the vertical component of the image, and some recent projectors can automatically detect the projection surface and can automatically keystone the image to fit.
Before data projectors, special lenses were available for slide or film projectors to apply the keystone effect.
The term comes from the wedge-shape of the stone placed at the top of an arch to spread the load of the wall above equally down both sides of the arch.

LCD / L.C.D.
Liquid Crystal Display. LCD displays are in use on electrical and electronic equipment across the world, and LCD technology is also used in video projectors.
See also TFT.
How LCDs work

LED / L.E.D.
Red LED (RS Components) Light Emitting Diode. LED technology has transformed stage lighting, at a time when energy efficiency is at the top of many agendas. The best LED luminaires for theatre are, however, still expensive, but getting cheaper. Cheaper units have noisy fans and may have issues with flickering on video recordings of shows, as well as poor dimmer curves and low CRI (colour rendering index) values. 
LED light sources are extremely efficient, and give off very little heat, making them ideal for display or architectural work. LED video walls are in use all over the world - they are more efficient and lighter in weight than projection alternatives.
The LED Museum
How LEDs work

A measure of light output from a source. The brightness of video projectors is stated in Lumens.
See also LUX.
What Lumen rating projector should I use?

1) A measurement of the intensity of light emitted from a surface per unit area in a given direction (unit is candela per square metre, or nit).
See also Foot-Lamberts.
2) The component of a television signal which carries information on the brightness of the image. See also HUE (which is the component which carries the colour information).

High quality domestic camcorder digital video format. See also DV.

Stereo Minijack (3.5mm) to 2 x Jacks (6.35mm) Also known as a 3.5mm jack, this is found as a headphone outlet on many pieces of personal audio equipment or laptops. A minijack to twin-phono cable is used to connect from a laptop, phone or MP3 player into a sound system or mixing desk that has phono ('pin plug') input connections.

1) Drama exercise involving two performers facing one another, either side of an imaginary mirror line. One tries to exactly duplicate the movements of the other, as if they were a reflection of that person in a mirror.
2) (AV/IT) Function on a laptop computer where the built-in display output is duplicated on the projector output. Turning off mirroring enables software such as Qlab to display a cue list / controls on the laptop display while the projector output shows the media (still images, videos or live cameras) required for the show. 

A technique from the film special effects and video game industry which enables a video artist or choreographer to 'capture' the movements of an actor or dancer digitally so that those movements can be reproduced by a virtual actor or dancer that's been computer-generated. 
See also Performance Capture.
DanceTech Motion Capture page

MP4 is a multimedia container format, which can store video, audio or still images.
See also MP3 (audio only)
What is MP4?

System for sending high quality digital video over IP networks. 

A digital system used in British television to provide video signals with high-quality stereo sound.
The term is an acronym for Near Instantaneous Companded Audio Multiplex. Developed in the 1970s in the UK, it was used in the 1980s as the method of compressing stereo audio to transmit it to the public. A NICAM video recorder (or a NICAM TV set) could reproduce good quality stereo sound. 

Acronym for Non-Linear Editor. This is audio, video or image editing software in which the original content is not altered in the editing process.

North American Television Standards Committee. TV standard in the USA.
More about TV standards


A medium-sized projector for glass slides used in cinemas for introductory titles and captions between film presentations, around 1930-1970. 
More information coming soon.

Overhead Projector (OHP) - Nobo 2511 Desktop Projector Classroom projector commonly used before digital projection became affordable, where text or images printed or drawn/written on a horizontally-placed acetate (clear plastic) film can be projected via a lens and mirror onto a vertical wall or surface. Still used for shadow-puppetry in small-scale applications (where bright, clear images can be obtained from small puppets placed on the horizontal platform), and in scenic / prop applications where a line drawing printed onto acetate can be hugely enlarged to trace onto a large piece of scenery / cloth, hung vertically.

Phase Alternate Line. TV standard in the UK and Europe.
More about TV standards

Technique used in special-effects films to transfer the facial performance of an actor on a motion capture stage onto a digitally-created avatar (creature / character). A head-worn mini-camera captures a static image of the actors' face regardless of their head movements, and their key-features (eyes, mouth) are recorded and transferred direct to the digital avatar. 
The technique was pioneered on James Cameron's Avatar and has been used on a range of projects since. 
See also MOTION CAPTURE which concentrates only on body movements, and the facial expressions are animated afterwards. 

A handheld digital projector, usually battery-powered. Many different models are available, with a wide range of brightness levels (measured in Lumens). Also known as mini projector, mini beamer, pocket projector.

The ability with some advanced lighting desks and LED lighting fixtures to make each LED component within the fixture respond to a video signal. With a large number of LED fixtures, incredible fluid effects are possible that would take days to program manually.

(Trade Name) Microsoft program for displaying slides on a PC. Has become the standard for simple slide-based presentations.

(Trade Name) Software program by Adobe used for editing of digital video.
Adobe website

1) Slides are used to project still archive images or textures. Libraries of slides contain images for every occasion. Kodak Carousel projectors are the industry standard, and some types can be linked to a controller to perform complex dissolves and fades from one projector to another. More powerful projectors are available using very intense discharge sources and large format glass slides to produce a massive image.
2) Lighting effects : Moving cloud / rain / fire effects can be achieved using a powerful lantern known as an effects projector with a motorised glass disc painted with the required effect. An objective lens is required in front of the disc to focus the image. See Effects.
3) Gobos : See GOBO.
4) Film : 35mm film projection is common in many theatres as a device for keeping the building open to the public when productions are in preparation. 16mm film projection is used in smaller venues. Film projection can, of course, also be integrated into a performance.
5) Data: Data or Video projection is now being used to bring video and computer images to the large screen. Data projectors are considerably cheaper and more versatile than other methods, and the quality is improving all of the time. Images can be front projected or back/rear projected depending on the amount of space and the effect required. For example, if actors are required to walk in front of the screen and not have the image appearing on them, back projection is the only answer.
6) Front Projection: The projector(s) are in front of the projection surface or screen, between the screen and the audience. This results in a bright image, but means that actors standing directly in front of the screen may cast a shadow on the screen (and have projection on their faces). 
7) Rear Projection / Back Projection: The projector is behind the projection surface. This means the projection image will be reversed from the point of view of the audience (all data projectors have a setting to flip or mirror the image). A standard white cloth or sheet can be used, but the image will be dimmer than it would be from the front, and (most importantly) the projector lens will be visible as a bright hot spot in the projection. To avoid this, a custom-made back projection screen should be used. Companies such as Rosco sell back projection (BP) material (a translucent plastic) which results in a very bright and clear image, and which prevents the visibility of a projection hot spot. The BP material can be stapled to a frame to form a screen of the exact size needed for the event. 

1) The point during a drama when the plotline reaches a conclusion, and conflict is resolved.
2) A measure of the quality of a video display / projection. Measured in the number of pixels width x height. 
3) The quality of a sound sample is measured by the sample rate (e.g. 44.1kHz is CD quality sample rate) and the resolution (either 8 bit or 16 bit normally).

Red Green Blue. Video connection standard using three connections for the three colours which make up the final image. Provides a higher quality image than standard composite video.

Standard 8-pin connector used for ethernet / network connections between computer-based devices. 
Used in theatre for carrying audio and video signals over long distances. 

Video format launched by JVC in 1987. S-VHS resolution is 400 horizontal lines. See also VHS.


SCART is a 21-pin connector standard which transmits full video and audio signals. Also known as Peritel, Peri TV, or Euroconnector. SCART cables are sometimes uni-directional, and care needs to be taken to ensure the correct cable is used for a particular application. The cables are notoriously unreliable in heavy duty situations, and pins get broken or pushed in fairly easily. However, handled with care, and left in equipment, they are perfectly fine.
Main definition submitted by Stephen Bourke.

Stands for Serial Digital Interface. A standard for digital video transmission over 75 ohm coaxial cable, using BNC connections.

Television standard used mainly in France and former USSR. Stands for 'Séquential Couleur Á Mémoire'
Uses 625 lines of resolution like PAL and 25 frames per second, but has a colour processing system not compatible with other systems. See also PAL and NTSC.
More about TV standards

A range of terms are used to describe how a particular filmed image looks. This terminology is also sometimes used for followspot size descriptions. 

Extreme Wide Shot (ELS / EWS)
Wide Shot (WS) / Long Shot (LS)
Full Shot (FS) - Full body is seen (from top of head to feet).
Medium Long Shot (MLS) / Medium Wide Shot (MWS)
Medium Shot (MS)
Medium Close Up (MCU)
Close Up (CU)
Extreme Close Up (ECU)

See the link below for visuals showing the types of shots. 
Careers In Film -Types of Shots

A wide range of video recordings of performances are available in a huge number of archives. 
Examples include:
Broadway HD (
Digital Theatre (
Drama Online (
National Theatre Collection (
Shakespeare's Globe (
WhatsOnStage (

35mm slides on a light table (Dusan (canstockphoto)) See PROJECTION.

Glass (or film that can be applied to existing glass) which can make a window opaque when an electric current is passed through it.

(pronounced 'SIMPTEE') SMPTE stands for Society of Motion Picture and Television Engineers (US). 
The term refers to a timecode for synchronising pre-recorded show elements (e.g. sound or video) with other elements. For example, a timecoded 'click' is played to the musicial director to enable her/him to keep in time, and lighting and video cues are triggered at a particular time within the piece of music. Timecode is measured in hours, minutes, seconds and frames. There are usually 30 frames per second, meaning an accuracy of 1/30th of a second is possible. 
Where the timecode is played as an audio track, it's known as Linear Timecode (LTC). 
SMPTE website Controlling Lighting and Sound With Timecode

Originally an accessory to a computer which equips the PC with the ability to play back and record sound. Early Windows sound interfaces were the Creative Sound Blaster (from 1981 - present) or cards made by Turtle Beach.
The term now (sometimes) refers to any external sound interface designed to allow multiple audio devices to connect to a Windows or Mac (or other) computer. External sound cards / audio interfaces were connected via FireWire, and are now connected via USB. 

(Trade name) A combination harness and camera support which (with practice) enables a handheld camera to appear to float through a scene. Any movements of the camera operator are cancelled out by the design of the harness.
The original Steadicam was invented in 1975 by camera operator Garrett Brown and used on projects such as Rocky and The Shining.
There are variations based on motorised gimbals which can actively cancel out any operator movements, which are much easier to use.
Tiffen Steadicam website

Text projected on a screen above the stage, so the audience can read translations of the text of (e.g.) an opera. 
Surtitles may be projected onto a horizontal screen made for the purpose, or possibly directly on the wall above the proscenium arch. 
Using a standard data projector this may result in spill of 'video gray' on the stage, in which case a mask can be made to cut off unwanted light and positioned around 10-15cm in front of the projector, or a projector dowser can be used to cut off the projection entirely when titles are not required. 

Super Video Graphics Array.

Open-source Mac OS X technology that allows applications to share video frames with one another in realtime. 
Can be used with Qlab to get the output of any Mac application into a Qlab workflow.
Syphon website

Thin Film Transistor. Technology used in flat screen displays (laptop computers, flat screen monitors, colour screen handheld computers and mobile phones). TFT screens are better resolution than LCD panels, but are more expensive. Sometimes known as Active-Matrix LCDs.
Each pixel is controlled by up to four transistors.
How TFTs work

Figure used to calculate how large a projected image will be for a given distance to the screen (or vice versa).
For example, a throw ratio of 2.5 means that to achieve an image 4 feet across, the projector must be (4 x 2.5 = 10) 10 feet from the screen.
A projector 8 feet from the screen will result in an image (8 / 2.5 = 3.2) 3.2 feet across.
A short throw projector with a ratio of less than 1 will produce a larger image for a smaller throw.

TNC Male Clamp Type connector (from Threaded coaxial connector, similar to a BNC (which has a locking ring). The initials stand for Threaded Neill Concelman.
See also BNC.

1) The movement of actors / scenery & change of lighting / sound between one scene and another.
2) Video: An effect applied to a change of shot / camera angle to make it anything other than a simple cut.

35mm slides on a light table (Dusan (canstockphoto)) 1) The property of an item which is see-through. 
2) A transparent photograph image which can be projected. Commonly referred to a 35mm slide, designed to be used in a slide projector such as the Kodak Carousel. 

Triaxial Cable, often referred to as triax for short, is a type of electrical cable similar to coaxial cable, but with the addition of an extra layer of insulation and a second conducting sheath. It provides greater bandwidth and rejection of interference than coax, but is more expensive.

Acronym for Visual Display Screen (or Video Display Screen). Sometimes used to describe any monitor / screen, but the term is a bit archaic now. 

Acronym of Video Graphics Array. Video display standard for computers, and the generic name of the 3 row, 15 pin connector with a blue plastic infill which is used to connect an external monitor on many PC desktop and laptop models.

Video recording format invented by JVC (Japan Victor Company) in 1976. The name stands for VIDEO HOME SYSTEM. VHS resolution is 250 horizontal lines.

Compact VHS tape cassette camcorder format using the same tape as VHS in a smaller cassette. Adaptors are used to extend the cassette size so that it can be viewed in a full-size VHS player.

Term from the film industry for a base where the material being shot can be previewed and reviewed on monitor screens. Often now used for the base of the AV / projection department.
Sometimes called the less-alliterative VIDEO WORLD, where it usually applies to the AV / projection department of a live event. 

8mm domestic analogue video format. Popular between 1985 and 2007, due to the quality improvement over VHS-C, and due to the compact camcorders. The format was replaced by Mini-DV, from 1995. 
See also HI-8.
Wikipedia entry

Roland V-4EX Vision Mixer Mixer to use with live cameras to enable multiple camera to be mixed into a single video output (e.g. a projector or a broadcast feed). There are some quite basic which simply switch between inputs, and others which enable partial mixing between inputs, removing a greenscreen background, adding live video effects etc. 

An artist that mixes video into a live performance on the fly. The term derives from DJ (Disc Jockey), who plays music for club nights, parties or events.

(Short for Video Tape) A pre-recorded video clip that is played in during a live performance.

Short for eXtended Graphics Array. Computer display standard introduced by IBM in 1990. XGA offers a resolution of 1024x768 pixels with 256 colours, or 640x480 with 16 bit colour.
XGA-2 was added later and offered 1024x768 pixels with high colour, and 1360x1024 with 16 colours.