Understanding AV Terms and Acronyms

If you struggle trying to keep up with or understanding all those AV terms and acronyms, CIE's HowToAV team of AV experts and engineers are here with all the answers

Glossary of Audio Visual terms, technologies and abbreviations

We'll keep this page up to date with all the latest explanations of technologies, AV terms and decyphering all those initials that (apparently!) we're all supposed to know!...


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100v line

... or Constant Voltage Loudspeaker System provides a stable method of audio distribution/installation using voltage (provided via an amplifier) and step down transformers (normally mounted within the loudspeakers). Advantages of 100v systems are the distance/lengths of the loudspeaker cable runs and the ability to add or remove loudspeakers from the system.

24fps (24p)

Refers to a video format that operates at 24 frames per second remove with progressive scanning.

4K Resolution

4K Ultra High Definition (UHD) is the next generation of improved resolution television, providing 3840 x 2160 pixels.

5 GHz

Wireless technology using the unlicensed 5GHz frequency bands.

50 Hz

Common Frame rate (image change rate) for video within Europe.

60 Hz

Common Frame rate (image change rate) for video within America/Japan.


Surround sound that delivers 6 Channels of audio, 5 standard speakers and 1 Sub-woofer.


Surround sound that delivers 8 Channels of audio, 7 standard speakers and 1 Sub-woofer.

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ADC (A/D Converter)

An IC Chip that converts analogue Audio Visual signals into digital.


Audio Frequency Induction Loop System. See Induction Loop System.

AoIP Audio over IP allows audio signals to be transmitted via LAN, WAN or web to IP-addressable end-pionts, IP loudspeakers or IP amplifiers for control and distribution to multi-zone, multi-site PA systems.


Audio Visual - Products for recording, processing or reproduction of picture and/or sound are given this label.

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Background Music - low level music distributed via a PA system.


In computer and digital terminology a bit is the smallest unit of data. It is expressed in binary notation so that it is either 0 or 1–basically an 'off' or an 'on' switch. The word 'bit' is an amalgam of 'binary' and 'digit'.

Bit rate

The number of bits that are transferred or processed per unit of time.


Bluetooth is a wireless protocol for exchanging data over short distances from fixed and mobile devices. Commonly used for audio and mobile telephone headsets / handsfree applications. Operates in the 2.4GHz band.


Is the digital form of Multi-channel audio data (e.g., 5.1 Channel) before it is decoded into its various formats.

Block Noise Reduction

MPEG digital video compression works by compressing square areas of pixels. Under some conditions, an artifact called 'block noise' can occur in the picture. Block Noise Reduction processes the noise blocks so that they become less visible.


The Blu-ray Disc™ is a high-density optical disc format designed for storage of high-definition video and data.

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Consumer Electronics Control provides a limited amount of device-to-device control (eg. by powering up a BluRay player, automatically changes the HDMI input on the connected television)

Channel 38 A frequency band that radio microphones can operate in (606 MHz - 614 MHz). Normally a licence is required in the UK from JFMG to operate in this band.

Coaxial Digital Audio

Coaxial digital cables are the most common type of connection cable used for digital audio. They look similar to the RCA cables that many people use and are familiar with. The only difference is that it carries digital instead of analogue signals.

Component Video

Video signal is separated into its component form i.e. red, green (sync) and blue and referred to as YUV. (also see YPbPr and YCbCr). Component Video signal is the same as YUV where Y = luminance Pb = blue minus luminance and Pr = red minus luminance.

Composite Video

The composite video signal is where the luminance and chrominance are mixed together with sink information down a single cable.


Is the signal used in video systems to convey the colour information of the picture.

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DAC (D/A converter)

An IC Chip that converts digital signals into analogue.

Deep Colour

Is a term used to describe a gamut (colour space) comprising a billion or more colours. The HDMI 1.3 specification supports Deep Colour bit depths. It defines bit depths for Deep Colour as 30 (10) bits (1.073 billion colours), 36 (12) bits (68.71 billion colours) and 48 (16) bits (281.5 trillion colours).

Display Port

Digital interface transmitting HD video, audio and data signals.

Dolby TrueHD

Dolby TrueHD is an advanced lossless Multi-channel audio codec developed by Dolby Laboratories which is intended primarily for high-definition home-entertainment equipment such as Blu-ray discs.

Dolby Digital Plus (DD+)

A digital audio compression format developed from the earlier Dolby Digital, increasing quality and available Channels.

DTS-HD Master Audio

Is a lossless audio codec created by Digital Theater Systems, developed from the earlier DTS with increased sampling frequency and bit rate.

Dynamic Range

Dynamic range describes the ratio of the quietist sound to the loudest sound in a musical instrument or piece of electronic equipment.


Is the reduction of video signal from one size (resolution) to another.


Digital Video Interface is a video interface standard designed to provide very high visual quality on digital display devices such as flat panel LCD displays and digital projectors.

Digital Noise Reduction

Eliminates unwanted colour noise from the video signal for smoother image reproduction.

De-interlaced Video

A video image is made up of a series of still images played in rapid succession, this is divided into a series of scan lines drawn on the display, de-interlaced video draws all these scan lines in one pass.

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EN 54 is a mandatory standard that specifies the requirements and test procedure for every component of a fire alarm and detection system.


EDID ('Extended Display Identification Data' for short!) is a data command structure provided from a digital display (ie. Screen, TV or projector) which communicates its capabilities to the AV system. EDID data typically includes manufacturer name, model and serial number, display size, resolution, luminance information, etc.


A PC interface used to connect computers and peripherals in a Local Area Network (LAN).

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Microphone Feedback (also known as the 'Larson Effect') is the disturbing howl/squeal/buzz noise created when a microphone and loudspeaker negatively affect one another.
Feedback occurs when sound from loudspeakers is picked up by the microphone, re-amplified and picked-up again from the speakers. This continuous loop results in the howl or rumble of the feedback effect.

Frequency Response Describes the general output frequency range of a device/amplifier.

Full HD

1920 x 1080p (progressive) video resolution.

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High Definition.

HD Ready

TVs that can display High Definition content in both 720p and 1080i formats as a minimum standard.


Hard disk drive.


High definition television.


Transmits converged uncompressed full HD digital video, audio, 100 BaseT Ethernet, Power-over-Ethernet (PoE) and various control signals through a single Cat5e/6/7 cable over distance of up to 100 metres. Utilising its full features is known as HDBaseT '5Play'.

HDBaseT Lite

Reduced function, lower cost version of HDBaseT; this 3Play 'Lite'version transmits HD video, audio and control signals through a single Cat5e/6/7 cable over distance of up to 60 metres.


Stands for High-Definition Multimedia Interface and provides an easy and convenient way of connecting digital audio-video components.

HDMI v1.x

Different HDMI specifications released by HDMI LLC.

HDMI 2.0/2.0a

With HDMI 2.0, among the many new features the increase in data speed from 10.2 to 18 Gbit/s is by far the most important. This increase in speed allows HDMI 2.0 to carry 4K resolution at 60 frames per second. Other features of HDMI 2.0 include; up to 32 audio channels for a multi-dimensional immersive audio experience, up to 1536kHz audio sample frequency for the highest audio fidelity, simultaneous delivery of dual video streams to multiple users on the same screen, simultaneous delivery of multi-stream audio to multiple users (up to 4), support for the wide angle theatrical 21:9 video aspect ratio, dynamic synchronization of video and audio streams, CEC extensions provides expanded command and control of consumer electronics devices through a single control point. Support for BT.2020 Colorimetry with 10 or more bits of colour depth.

The latest revision HDMI 2.0a, adds support for High Dynamic Range (HDR). HDR for TVs promises more realistic video with brighter bright and darker dark. This technology comes under various guises and names depending on the manufacturer

HDMI over IP

HDMI over IP technology converts HDMI signals to TCP/IP packets and delivers them across a network utilizing the same CAT wiring that is already in place for standard IP Networks such as Ethernet.

By using H.264 compression technology (as used by Blu-ray and Netflix) HDMI over IP allows you to send signals up to 4K over standard gigabit LAN networks including Ethernet switches.

Although H.264 is not lossless compression in the strict mathematical sense, the amount of loss is typically imperceptible. The latency of H.264 is ultra-low with the signal delay down to an unnoticeable two or three frames per second.


Stands for High-bandwidth Digital Content Protection. It is a copy-protection scheme developed by Intel to be used in conjunction with DVI and HDMI connections.

HDCP 2.2

The latest version of the High-bandwidth Digital Content Protection protocol specifically developed to support 4K UHD content.

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Induction loop System

An Induction loop System (also known as an Audio Frequency Induction Loop, AFILS or Hearing Loop) is an assistive hearing system providing access to sound distribution for those wearing a hearing aid. Often integrated into with a standard 100v Line PA System.

Ingress Protection

Also known as I.P. Rating, Ingress Protection is the characteristic of a product in terms of its resistance to the penetration of solid objects and liquids. Indicated by the letters IP (International Protection) followed by two numbers; the first number = protection against solid object ingress, the second being protection against liquid ingress. Often related to outdoor or harsh environment products such as loudspeakers and surveillance cameras.

Interlaced Video

A video image is made up of a series of still images played in rapid succession; this is divided into a series of scan lines drawn on the display. Interlaced video draws all these scan lines in two passes.


Internet protocol.

I.P. Rating

See Ingress Protection.


Infrared, commonly used as a wireless line of sight control for AV equipment.

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JPEG stands for Joint Photographic Experts Group, a consortium that has developed and spread this format worldwide. It is a compression format that efficiently stores digital images.

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Key Selection Vector. A unique numerical key in HDCP content protection.

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Liquid Crystal Display, high quality LCD display gives a clearer picture with excellent colour, contrast and detail, also used with some projectors.


Light-emitting Diode, a semiconductor device that emits visible light when an electric current passes through it.

Low Impedance

Also referred to as Low Z - the resistance of a loudspeaker or load capability of an amplifier, usually expressed in Ohms. Typical impedance levels are 4ohm, 8ohm or 16ohm. Low Z systems are typically used in high power music reproduction systems.

Low Z

See Low Impedance


Linear Pulse Code Modulation is an uncompressed audio technology. Instead of compressing sound data, it simply stores the information as it is, giving you an exact copy of the original. Various bit and sampling rates can be used.


This is the signal used in video systems to convey the light information of the picture.

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Stands for Motion Picture Experts Group and represents a family of digital audio and video coding standards. MPEG4 has a high compression ratio, which creates a small file size that is suitable for personal computer and Internet applications.

Motion Adaptive Field Noise Reduction

This new noise-reduction technology reduces background noise, without having an effect on moving objects.

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NFC / Near Field Communication

Advanced NFC (Near Field Communication) technology allows 2-way wireless communication between electronic devices. The devices communicate over a short distance (usually up to a maximum of 4 cm) and it is precisely this very short range that ensures the security of this technology.

An employee / user can use their NFC-enabled smart phone to gain secure access to a building by placing it in close proximity to a suitable access unit.

NFC technology can be used as an alternative to an RFID card/pass system.


In the US and Japan, NTSC (National Standards Television Committee) is the standard used for all video equipment. NTSC uses 525 lines to make up a TV picture and scans at 60 Hz.

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On Screen Display.

Optical Digital Audio

Optical digital cables use the Toslink connector, these use pulses of light to transmit digital audio data. Optical uses light thus it is immune to interference from electromagnetic and radio frequencies.

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PA (Public Address)

Public Address / Public Address System. An electronics audio amplification system (usually for voice and background music), including amplification, loudspeakers and sound source (microphone, music source, etc).


Phase Alternation Line, this is the video standard used most commonly in Europe. PAL uses 625 lines to make up a TV picture and scans at 50Hz.


A passive speaker doesn't have a built-in amplifier, it needs to be connected to an amplifier to provide the current to make it work.


Pulse Code Modulation, digital bitstream audio format commonly supporting 16 bit up to 48kHz sampling frequency in stereo.

Phantom Power

A DC power source used for providing voltage to operate microphones that contain active electronic circuitry such as condenser/electret types down the microphone cable line. Usually provided by the source equipment (Mixer Desk/PreAmp/Amplifier) various voltage options are available between 3~52v DC. Separate Phantom Power PSU devices are also available.


Short for Picture Element, Pixels are the tiny dots of information that make up a digital image. The more pixels there are on the camera's image sensor (CCD or CMOS) or display, the higher the image resolution will be.

PoC / Power over Cable

Similar to PoE (or Power over Ethernet), PoC / Power over Cable allows for both data and power to be sent simultaneously over the cable (usually Cat5e/Cat6).

Frequently utilised in HDBaseT and HDMI-over-Cat cable systems, PoC will send power from the Transmitter / Splitter / Matrix to power the Receiver at the remote end of the connection, negating the need for a mains power supply at the Receiver.

PoE / Power over Ethernet

Power over Ethernet – also known as PoE – describes systems which allow for power and data to be simultaneously sent over the same data / Ethernet cable, with the power being supplied by an Ethernet Router or Switch.

PoE is often used to supply power at the remote end of a transmission over a Cat cable system (such as IP cameras, IP telephones, etc.) where local power may not be available or where reduced cable connectivity is beneficial to the installation.



Powered speakers, also known as self-powered speakers or active speakers have built-in amplifiers. They can be connected directly to an audio source, such as a Mixer/ Pre Amp or Music Player without the need for an external amplifier.

Progressive Scan

A sales term for describing de-interlaced video.


Personal Video Recorder, a device that records video without videotapes or discs.

Pass Through

Video by-pass output; outputs an additional copy of the original input signal.

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Receiver (RX)

Receives AV signals through various interconnects after being sent by compatible transmitter.


Recording Company of America, RCA (or Phono) is the standard way of connecting audio and video components.


Stands for red, green and blue. A video connector or lead which offers RGB output carries these primary colours separately for greater picture quality.


The RJ45 is a connector used on CAT cabling for connecting computers and other devices to local area networks (LANs).


'Root Mean Squared' - the formula used to calculate an approximate average the power an amplifier can continuously create and a speaker receives.


Is a voltage loop interface for two-way (full-duplex) communication.


The amount of pixels in an image. The higher the resolution, the more detailed the picture will be.

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The French broadcast system. Sequential Coleur A Memoire uses 625 lines scanned at 50Hz.


SIP-which stands for 'Session Initiation Protocol'-is a standard protocol to establish, modify or terminate multimedia sessions (video, voice, chat, gaming, and virtual reality) or internet telephony calls. It is most commonly used in internet telephony for voice and video calls over Internet Protocol (IP) networks, as well as audio multicast meetings and instant messaging conferences. In the world of VoIP, SIP, as the name suggests, is a call setup protocol (as opposed to a 'data transfer' protocol) and is needed in a voice call, for example, to get two telephones talking. SIP can run over IPv4 and IPv6 and it can use either TCP or UDP.


A high quality video connection which offers better picture quality than standard composite video. S-Video cables have round, mini four-pin plugs and sockets.

Sampling Rate

Sampling is the process of converting the heights of a sound wave (analogue signal) taken and converted at set periods into digits (digital encoding). Sampling frequency is the number of samples taken per second, so larger numbers mean more faithful reproduction of the original sound.


An audio/video connector to carry the audio & video signals on one convenient cable.


Standard Definition, traditional format used for TV made up of 576 (visible) Horizontal lines (PAL).


Stereophonic sound, commonly called stereo, is the reproduction of sound using two or more independent audio Channels through a symmetrical configuration of loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing.

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Time Base Corrector, ensures optimum playback picture quality even in freeze frames or slow motion and also compensates for any irregular movement of the tape transportation mechanism.


Transmits AV signal through various interconnects and is accepted by a compatible receiver.


See Optical Digital Audio.

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Ultra HD or Ultra High Definition consumer display format with a resolution of 3840 x 2160. It is increasingly referred to as '4K UHD'. A UHD display will deliver four times as much detail as the Full HD (1080p) displays we're so familiar with, with around 8 million pixels per screen. This technology is also starting to feature in cameras, smartphones and tablets, as well as computer monitors and PC games.


Universal Serial Bus. A connection port for transferring digital data, generally used on PCs.

USB 3.1

The latest revision of USB utilises a new transfer technology called 'SuperSpeedPlus' which as the name suggests significantly increases data transfer speeds compared with the previous USB 2.0 and 3.0. With a huge boost in bandwidth, USB 3.1 SuperSpeedPlus delivers an incredible 10 Gbps data transfer speed. USB 3.1 also supports 'QuickCharge' - delivering a massive 100 Watts of power!

USB Type C

The latest USB connector - Type C is smaller than previous versions, rotatable (you won't have the annoyance of trying to plug in a connector 'the wrong way up') and features the new, increased oin coniguration to support full USB version 3.1.


Is the conversion of a video signal from one size (resolution) to another, upscalers increase the resolution.

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Voice over IP / VoIP

Voice over IP (VoIP) is a category of hardware and software used to manage the delivery of voice information over Internet Protocol (IP) networks, such as the internet, and involves sending voice information in digital form in discrete packets. The main advantages of VoIP over traditional telephony are its relatively inexpensive implementation costs and its versatility. That said, there is a greater likelihood of dropped calls and degraded voice quality when the underlying network is heavily used. Other terms commonly associated with VoIP are IP telephony, Internet telephony, broadband telephony, and broadband phone service.

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Screen display ratio providing a greater width-to-height ratio. The 'standard' widescreen ratio is 16:9 (compared with the traditional TV ratio of 4:3).


Devices which are Wi-Fi or Wireless enabled are able to connect to a local area network and send/receive data without the need for a physical (wired) connection.

Wireless Inductive Charging Set to be one of the next key must-have functions in smartphone and handheld devices, wireless inductive charging allows for connector / cable-free charging of battery powered devices.

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Extended gamut YCC (also called x.v.Colour) is a colour space that can be used in the video electronics of television sets to support a gamut 1.8 times larger than that of standard sRGB colour space.

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Refers to Component video (YUV) at a higher resolution than standard definition.


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