Audio and video interfaces and connectors

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Audio connectors and video connectors are electrical or optical connectors for carrying audio or video signals. Audio interfaces or video interfaces define physical parameters and interpretation of signals. For digital audio and digital video, this can be thought of as defining the physical layer, data link layer, and most or all of the application layer. For analog audio and analog video these functions are all represented in a single signal specification like NTSC or the direct speaker-driving signal of analog audio.

Contents

Physical characteristics of the electrical or optical equipment include the types and numbers of wires required, voltages, frequencies, optical intensity, and the physical design of the connectors. Any data link layer details define how application data is encapsulated (for example for synchronization or error-correction). Application layer details define the actual audio or video format being transmitted, often incorporating codecs not specific to the interface, such as PCM, MPEG-2, or the DTS Coherent Acoustics codec. In some cases, the application layer is left open; for example, HDMI contains an Ethernet channel for general data transmission.

Some types of connectors are used by multiple hardware interfaces; for example, RCA connectors are used both by the composite video and component video interfaces, but DVI is the only interface that uses the DVI connector. This means that in some cases not all components with physically compatible connectors will actually work together.

Analog A/V connectors often use shielded cables to inhibit radio frequency interference (RFI) and noise.

Interfaces and their connectors

InterfaceConnectors
Audio or videoDigital or analogDescription
Audio onlyAnalogOften unmarked on consumer audio equipment since it is so common, or labelled with headphones symbol or as "line out". Computers and other equipment sometimes use Microsoft-Intel color coding scheme, especially when there are multiple input/output plugs. 3.5 mm TRS minijack
RCA connector
Balanced audio 6.35 mm TRS audio jack (shielded twisted pair),
XLR (shielded twisted pair)
Digital S/PDIF (Sony/Philips Digital Interconnect Format). Via coaxial or optical cables. RCA jack (coaxial),
TOSLINK (optical),
BNC (rare)
AES3 (also known as AES/EBU) RCA jack (coaxial),
XLR (shielded twisted pair),
TOSLINK (optical),
BNC
MADI BNC (coaxial),
ST (optical)
Video onlyAnalog Video Graphics Array (VGA) D-subminiature 15-pin
Composite. Often designated by the CVBS acronym, meaning "Color, Video, Blank and Sync". RCA jack, normally yellow (often accompanied with red and white for right and left audio channels respectively)
S-Video (Separate Video). Carries standard definition video and does not carry audio on the same cable. Mini-DIN 4-pin
Component. In popular use, it refers to a type of analog video information that is transmitted or stored as three separate signals. Either RGB interfaces or YPbPr 3 RCA jacks
Composite, S-Video, and Component VIVO = Mini-DIN 9-pin with breakout cable.
Digital and analog Digital Visual Interface (DVI)DVI connector
Video and audioAnalog SCART (Peritel)SCART
Digital High-Definition Multimedia Interface (HDMI),BNCHDMI connector
DisplayPort DisplayPort connector
HDBaseT 8P8C connector
IEEE 1394 "FireWire" FireWire or i.LINK connectors

Multiple signals

Several generic digital data connection standards are designed to carry audio/video data along with other data and power:

Some digital connection standards were designed from the beginning to primarily carry audio and video signals simultaneously:

Many analog connectors carry both:

S/PDIF

S/PDIF is an audio-only format carried over electrical coaxial cable (with RCA jacks) or optical fibre (TOSLINK).

Note that there are no differences in the signals transmitted over optical or coaxial S/PDIF connectors—both carry exactly the same information. Selection of one over the other rests mainly on the availability of appropriate connectors on the chosen equipment and the preference and convenience of the user. Connections longer than 6 meters or so, or those requiring tight bends, should use coaxial cable, since the high light signal attenuation of TOSLINK cables limits its effective range.

HDMI

HDMI Type A socket HDMI.socket.png
HDMI Type A socket

High-Definition Multimedia Interface (HDMI) is a compact audio/video standard for transmitting uncompressed digital data.

There are three HDMI connector types. Type A and Type B were defined by the HDMI 1.0 specification. Type C was defined by the HDMI 1.3 specification. Type A is electrically compatible with single link DVI-D. Type B is electrically compatible with dual link DVI-D but has not yet been used in any products.

IEEE 1394 "FireWire"

The 6-circuit and 4-circuit alpha FireWire 400 connectors FireWire-46 Diagram.svg
The 6-circuit and 4-circuit alpha FireWire 400 connectors

IEEE 1394 (branded "FireWire") is a digital data transfer protocol commonly used for digital cameras (common on MiniDV tape camcorders), but also used for computer data and audio data transfers.

Unlike Point-to-Point connections listed above, IEEE 1394 is able to host several signals on the same wire, with the data delivered and shown on the destination set. It is also fully bi-directional, with its full bandwidth used in one direction or the other, or split directions up to its maximum. [1]

DisplayPort

External connector (source-side) on PCB DisplayPort Connector.svg
External connector (source-side) on PCB

DisplayPort is a digital display interface standard (approved May 2006, current version 1.4 published on March 1 2016). It defines a new license-free, royalty-free, digital audio/video interconnect, intended to be used primarily between a computer and its display monitor, or a computer and a home-theater system.

The video signal is not compatible with DVI or HDMI, but a DisplayPort connector can pass these signals through. DisplayPort is a competitor to the HDMI connector, the de facto digital connection for high-definition consumer electronics devices.

Audio connectors

Audio connectors are used for audio frequencies. They can be analog or digital.

Single-wire connectors used frequently for analog audio include:

Multi-conductor connectors:

Digital audio interfaces and interconnects:

Phone connector

2.5 mm (3/32") mono (TS), 3.5 mm (1/8") mono and stereo (TRS), and 6.3 mm (1/4") stereo (TRS) phone connectors Photo-audiojacks.jpg
2.5 mm (3/32") mono (TS), 3.5 mm (1/8") mono and stereo (TRS), and 6.3 mm (1/4") stereo (TRS) phone connectors

A phone connector (tip, ring, sleeve) also called an audio jack, phone plug, jack plug, stereo plug, mini-jack, or mini-stereo. This includes the original 6.35 mm (quarter inch) jack and the more recent 3.5 mm (miniature or 1/8 inch) and 2.5 mm (subminiature) jacks, both mono and stereo versions. There also exists 4.4 mm Pentaconn connectors.

DIN

Five-pin male 180deg DIN connector 5pin180dinplug.jpg
Five-pin male 180° DIN connector

A DIN connector is a connector that was originally standardized by the Deutsches Institut für Normung (DIN). Mini-DIN is a variation.

BNC

Male 50 ohm BNC connector BNC connector.jpg
Male 50 ohm BNC connector

The BNC connector is a very common type of RF connector used for terminating coaxial cable.

Clear TOSLINK cable with a round connector TOS LINK clear cable.jpg
Clear TOSLINK cable with a round connector

TOSLINK or Optical Cable is a standardized optical fiber connection system.

XLR

XLR3 cable connectors, female on left and male on right Xlr-connectors.jpg
XLR3 cable connectors, female on left and male on right

XLR connector plugs and sockets are used mostly in professional audio and video electronics cabling applications. XLR connector are also known as Cannon plugs after their original manufacturer. They are used for analog or digital balanced audio with a balanced line

Digital audio interfaces and interconnects with the AES/EBU interface also normally use an XLR connector.

RCA

RCA Plugs for composite video (yellow) and stereo audio (white and red) Composite-cables.jpg
RCA Plugs for composite video (yellow) and stereo audio (white and red)

RCA connectors, also known as phono connectors or phono plugs, are used for analog or digital audio or analog video. These were first used inside pre–World War II radio-phonographs to connect the turntable pickup to the radio chassis. They were not intended to be disconnected and reconnected frequently, and their retaining friction was quite sufficient for their original purpose. Furthermore, the design of both cable and chassis connectors was for minimum cost. Initially intended for audio-frequency connections only, the RCA plug was also used for analog composite video and non-critical radio-frequency applications.

Video connectors

A VGA connector SVGA port.jpg
A VGA connector

Video connectors carry only video signals. Common video-only connectors include:

Mini-DIN

mini-DIN 4 pin for S-Video SVideoConnector.jpg
mini-DIN 4 pin for S-Video

The Mini-DIN connectors are a family of multi-pin electrical connectors used in a variety of applications. Mini-DIN is similar to the larger, older DIN connector. Both are standards of the Deutsches Institut für Normung, the German standards body.

D-subminiature

DA, DB, DC, DD, and DE sized connectors DSubminiatures.svg
DA, DB, DC, DD, and DE sized connectors

D-subminiature or D-sub is a common type of electrical connector used particularly in computers. Calling them "sub-miniature" was appropriate when they were first introduced, but today they are among the largest common connectors used in computers. The DB25 is used for multi-track recording and other multi-channel audio, analog or digital (ADAT interface (DB25)), and was the standard connector for IBM compatible PC printer connection before USB and other connections became popular. It offered 8 simultaneous data pathways to the printer.

Video In Video Out

A graphics card with VIVO, DVI and VGA outputs Gpu-connector.jpg
A graphics card with VIVO, DVI and VGA outputs
A 6-connector VIVO splitter cable. From left to right: S-Video In, Component Pb out, Component Pr out, Component Y out/Composite out, Composite in, S-Video Out Vivo splitter cable.jpg
A 6-connector VIVO splitter cable. From left to right: S-Video In, Component Pb out, Component Pr out, Component Y out/Composite out, Composite in, S-Video Out

Video In Video Out, usually seen as the acronym VIVO (commonly pronounced vee-voh), is a graphics card port which enables some video cards to have bidirectional (input and output) video transfer through a Mini-DIN, usually of the 9-pin variety, and a specialised splitter cable (which can sometimes also transfer sound).

VIVO is found predominantly on high-end ATI video cards, although a few high-end NVIDIA video cards also have this port. VIVO on these graphics cards typically supports Composite, S-Video, and Component as outputs, and composite and S-Video as inputs. Many other video cards only support component and/or S-Video outputs to complement Video Graphics Array or DVI, typically using a component breakout cable and an S-Video cable.

DVI Connector

Color codes

Audio

white RCA/TSanalogue audio, left channel;
also mono (RCA/TS), stereo (TRS only),
or undefined/other
black RCA/TS/TRS
grey RCA/TS/TRS
red RCA/TSanalogue audio, right channel
orange RCA S/PDIF digital audio

For computers:

green TRS 3.5 mmstereo output, front channels
black TRS 3.5 mmstereo output, rear channels
grey TRS 3.5 mmstereo output, side channels
gold TRS 3.5 mmdual output, center and subwoofer
blue TRS 3.5 mmstereo input, line level
pink TRS† 3.5 mmmono microphone input
† Although the mic input is usually mono, the input is still a TRS phone socket. Many mono 'computer' mics are fitted with TRS plugs. The tip is for the MIC and the ring is for power (to power an electret-condenser style MIC).

There are exceptions to the above:

PC System Design Guide audio

Older sound cards had no common standard color codes until after PC 99. The PC System Design Guide (also known as the PC 97, PC 98, PC 99, or PC 2001 specification) is a series of hardware design requirements and recommendations for IBM PC compatible personal computers, compiled by Microsoft and Intel Corporation during 1997–2001. PC 99 introduced a color code for the various standard types of plugs and connectors used on PCs.

The color codes for audio plugs follow: [3]

Orange TRS 3.5 mmOutput, subwoofer
Blue TRS 3.5 mmInput, line level
Pink TRS† 3.5 mm microphone input
Lime TRS 3.5 mmOutput, front channels
Brown TRS 3.5 mmOutput, 'Right-to-left speaker'
Gold TRS 3.5 mm MIDI/game
† Though the input is often mono, the actual connector is usually still a 3-conductor TRS phone minijack. Many mono computer microphones have 3-conductor TRS plugs.

Video

yellow RCA/BNCcomposite video
red RCA/BNCred or Or/Cr chrominance
green RCA/BNCgreen or luminance
blue RCA/BNCblue or Pb/Cb chrominance
white BNChorizontal sync
black BNCvertical sync

Newer connectors are identified by their shape and not their colour.

Storage

For efficiency and simplicity, the same codec or signal convention is used by the storage medium. For example, VHS tapes can store a magnetic representation of an NTSC signal, and the specification for Blu-ray Discs incorporates PCM, MPEG-2, and DTS. Some playback devices can re-encode audio or video so that the format used for storage does not have to be the same as the format transmitted over the A/V interface (which is helpful if a projector or monitor cannot handle a newer codec).

See also

Related Research Articles

<span class="mw-page-title-main">Digital Visual Interface</span> Standard for transmitting digital video to a display

Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a video display controller, to a display device, such as a computer monitor. It was developed with the intention of creating an industry standard for the transfer of uncompressed digital video content.

<span class="mw-page-title-main">SCART</span> 21-pin connector for audio-visual equipment

SCART is a French-originated standard and associated 21-pin connector for connecting audio-visual (AV) equipment. The name SCART comes from Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs, "Radio and Television Receiver Manufacturers' Association", the French organisation that created the connector in the mid-1970s. The related European standard EN 50049 has then been refined and published in 1978 by CENELEC, calling it péritelevision, but it is commonly called by the abbreviation péritel in French.

<span class="mw-page-title-main">S/PDIF</span> Standardized digital audio interface

S/PDIF is a type of digital audio interface used in consumer audio equipment to output audio over relatively short distances. The signal is transmitted over either a coaxial cable or a fiber optic cable with TOSLINK connectors. S/PDIF interconnects components in home theaters and other digital high-fidelity systems.

<span class="mw-page-title-main">RCA connector</span> Electrical connector used for analog audio and video

The RCA connector is a type of electrical connector commonly used to carry audio and video signals. The name RCA derives from the company Radio Corporation of America, which introduced the design in the 1930s. The connector’s male plug and female jack are called RCA plug and RCA jack.

<span class="mw-page-title-main">S-Video</span> Signal format for standard-definition video

S-Video is an analog video signal format that carries standard-definition video, typically at 525 lines or 625 lines. It encodes video luma and chrominance on two separate channels, achieving higher image quality than composite video which encodes all video information on one channel. It also eliminates several types of visual defects such as dot crawl which commonly occur with composite video. Although it improved over composite video, S-Video has lower color resolution than component video, which is encoded over three channels.

A de facto standard is a custom or convention that has achieved a dominant position by public acceptance or market forces. De facto is a Latin phrase, here meaning "in practice but not necessarily ordained by law" or "in practice or actuality, but not officially established".

A DVD player is a device that plays DVDs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. Some DVD players will also play audio CDs. DVD players are connected to a television to watch the DVD content, which could be a movie, a recorded TV show, or other content.

<span class="mw-page-title-main">Component video</span> Video signal that has been split into component channels

Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Component video can be contrasted with composite video in which all the video information is combined into a single signal that is used in analog television. Like composite, component cables do not carry audio and are often paired with audio cables.

<span class="mw-page-title-main">DIN connector</span> Electrical connector

The DIN connector is an electrical connector that was standardized by the Deutsches Institut für Normung (DIN), the German Institute for Standards, in the mid 1950's, initial with 3 pins for mono, but when stereo connections and gear appeared in late 1950's, versions with 5 pins or more were launched. The male DIN connectors (plugs) feature a 13.2 mm diameter metal shield with a notch that limits the orientation in which plug and socket can mate. The range of DIN connectors, different only in the configuration of the pins, have been standardized as DIN 41524 / IEC/DIN EN 60130-9 ; DIN 45322 ; DIN 45329 / IEC/DIN EN 60130–9 ; and DIN 45326 / IEC/DIN EN 60130-9.

<span class="mw-page-title-main">HDMI</span> Proprietary interface for transmitting digital audio and video data

High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed 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. HDMI is a digital replacement for analog video standards.

<span class="mw-page-title-main">VGA connector</span> 15-pin video connector

The Video Graphics Array (VGA) connector is a standard connector used for computer video output. Originating with the 1987 IBM PS/2 and its VGA graphics system, the 15-pin connector went on to become ubiquitous on PCs, as well as many monitors, projectors and high-definition television sets.

<span class="mw-page-title-main">Composite monitor</span>

A composite monitor or composite video monitor is any analog video display that receives input in the form of an analog composite video signal to a defined specification. A composite video signal encodes all information on a single conductor; a composite cable has a single live conductor plus earth. Other equipment with display functionality includes monitors with more advanced interfaces and connectors giving a better picture, including analog VGA, and digital DVI, HDMI, and DisplayPort; and television (TV) receivers which are self-contained, receiving and displaying video RF broadcasts received with an internal tuner. Video monitors are used for displaying computer output, closed-circuit television and other applications requiring a two-dimensional monochrome or colour image.

<span class="mw-page-title-main">Patch cable</span> Cable used to connect electronic or optical devices

A patch cable, patch cord or patch lead is an electrical or optical cable used to connect one electronic or optical device to another for signal routing. Devices of different types are connected with patch cords.

<span class="mw-page-title-main">VESA Digital Flat Panel</span>

The VESA Digital Flat Panel (DFP) interface standard specifies a video connector and digital TMDS signaling for flat-panel displays. It features 20 pins and uses the PanelLink protocol; the standard is based on the preceding VESA Plug and Display (P&D) standard, ratified in 1997. Unlike the later, electrically-compatible Digital Visual Interface, DFP never achieved widespread implementation.

AV input stands for Audio/Visual input, which is a common label on a connector to receive (AV) audio/visual signals from electronic equipment that generates AV signals.

<span class="mw-page-title-main">Unified Display Interface</span>

Unified Display Interface (UDI) was a digital video interface specification released in 2006 which was based on Digital Visual Interface (DVI). It was intended to be a lower cost implementation while providing compatibility with existing High-Definition Multimedia Interface (HDMI) and DVI displays. Unlike HDMI, which is aimed at high-definition multimedia consumer electronics devices such as television monitors and DVD players, UDI was specifically targeted towards computer monitor and video card manufacturers and did not support the transfer of audio data. A contemporary rival standard, DisplayPort, gained significant industry support starting in 2007 and the UDI specification was abandoned shortly thereafter without having released any products.

<span class="mw-page-title-main">DMS-59</span>

DMS-59 was generally used for computer video cards. It provides two Digital Visual Interface (DVI) or Video Graphics Array (VGA) outputs in a single connector. A Y-style breakout cable is needed for the transition from the DMS-59 output to DVI (digital) or VGA (analogue), and different types of adapter cables exist. The connector is four pins high and 15 pins wide, with a single pin missing from the bottom row, in a D-shaped shell, with thumbscrews. As of December 2020, this adapter cable was listed as obsolete by its primary vendor Molex.

<span class="mw-page-title-main">Computer port (hardware)</span> Computer hardware

In computer hardware, a port serves as an interface between the computer and other computers or peripheral devices. In computer terms, a port generally refers to the part of a computing device available for connection to peripherals such as input and output devices. Computer ports have many uses, to connect a monitor, webcam, speakers, or other peripheral devices. On the physical layer, a computer port is a specialized outlet on a piece of equipment to which a plug or cable connects. Electronically, the several conductors where the port and cable contacts connect, provide a method to transfer signals between devices.

<span class="mw-page-title-main">Mini DisplayPort</span> Miniaturized version of the DisplayPort connector

The Mini DisplayPort is a miniaturized version of the DisplayPort audio-visual digital interface.

<span class="mw-page-title-main">TOSLINK</span> Standardized optical fiber digital audio interconnect

TOSLINK is a standardized optical fiber connector system. Also known generically as optical audio, its most common use is in consumer audio equipment, where it carries a digital audio stream from components such as CD and DVD players, Digital Audio Tape recorders, computers, and modern video game consoles, to an AV receiver that can decode two channels of uncompressed pulse-code modulated (PCM) audio or compressed 5.1/7.1 surround sound such as Dolby Digital or DTS Surround System. Unlike HDMI, TOSLINK does not have the bandwidth to carry the uncompressed versions of Dolby TrueHD, DTS-HD Master Audio, or more than two channels of PCM audio.

References

  1. "Archived copy" (PDF). Archived from the original (PDF) on 2011-06-06. Retrieved 2010-06-04.{{cite web}}: CS1 maint: archived copy as title (link) Demonstrating the multi-device capabilities of IEEE A/V network.
  2. "2.5mm Audio Cables". Archived from the original on September 26, 2013.
  3. "Chapter 3: PC 99 basic requirements". PC 99 System Design Guide (EXE). Intel Corporation and Microsoft Corporation. 14 July 1999. Archived from the original (EXE) on 16 February 2007. Retrieved 5 February 2009. Requirement 3.18.3: Systems use a color-coding scheme for connectors and ports. (Self-extracting zipped Word file)