Audio and video interfaces and connectors


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. Some connectors and interfaces carry either audio only or video only, whereas others carry both, audio and video.
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.
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. 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 and noise.

Interfaces and their connectors

Multiple signals

Several generic digital data connection standards are designed to carry audio/video data along with other data and power:
  • USB was designed as a single connector to support all needs, including any generic data, audio/video, power, and more; DisplayLink is its most successful Audio+Video protocol. Until the 3.0 revision, very low data rates meant most A/V needed alternative connectors.
  • USB-C can directly transport USB 3.1, DisplayPort, Thunderbolt, HDMI, and MHL protocols, with power, and audio and many other protocols are possible.
  • Thunderbolt is the successor to FireWire, a generic high-speed data link with well-defined audio/video uses. The latest Thunderbolt 3 uses USB-C as its connector, though not all USB-C is Thunderbolt-compatible.
  • FireWire is a generic data link with audio/video standards used on Camcorders, and high-end studio audio and video equipment.
  • DisplayPort carries digital audio and video, as well as auxiliary information, along with its Mini DisplayPort cousin.
  • 30-pin dock connector, a docking cradle for Apple iPod, iPhone and iPad, and its Lightning successor
  • Apple Display Connector, now-defunct Apple Display Connector
  • Ethernet using modular connectors supports audio over Ethernet, audio over IP, IPTV and other digital multimedia formats.
Some digital connection standards were designed from the beginning to primarily carry audio and video signals simultaneously:
Many analog connectors carry both:
S/PDIF is an audio-only format carried over electrical coaxial cable or optical fibre.
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

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"

is a digital data transfer protocol commonly used for digital cameras, 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.

DisplayPort

is a digital display interface standard. 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:
  • DB25 is for multi-track recording and other multi-channel audio, analog or digital
  • DIN connectors and mini-DIN connectors
  • Euroblock "European-style terminal block" or "Phoenix connectors", screw terminal connectors used for audio and control signals
  • RCA connectors, also known as phono connectors or phono plugs, used for analog or digital audio or analog video
  • Speakon connectors by Neutrik for loudspeakers
  • Phone connector also known as tip-ring-sleeve or tip-sleeve plug, phone plug, jack plug, mini-jack, and mini-stereo. This includes the original 6.35mm jack and the more recent and standard 3.5mm and 2.5mm jacks, both mono and stereo versions.
  • XLR connectors, also known as Cannon plugs, used for analog or digital balanced audio with a balanced line.
Digital audio interfaces and interconnects:
A phone connector also called an audio jack, phone plug, jack plug, stereo plug, mini-jack, or mini-stereo. This includes the original 6.35 mm jack and the more recent 3.5 mm and 2.5 mm jacks, both mono and stereo versions. There also exists 4.4 mm Pentaconn connectors.

DIN

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

BNC

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

TOSLINK

or Optical Cable is a standardized optical fiber connection system.

XLR

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

s, 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

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