Rating: 5/5

HDMI is a digital connection which carries video and embedded audio data.
It is currently the most common and popular connection type for digital projectors, displays and TVs.

There are various versions of HDMI with the different versions being able to support different maximum resolutions and bandwidth. These versions relate to the HDMI used in hardware rather than the cables used to connect to the hardware.

When it comes to the HDMI cables themselves, there are a few types as described below:

Rating: 4/5

Also known as: RGB, S-VGA, 15pin D-Sub

VGA is an analogue connection used primarily to connect a computer to a projector or display. It is slowly being supplanted by HDMI but most projectors and some large displays will still include a VGA input and sometimes output.

Good quality VGA cables can support Full HD resolution and WUXGA (1920 x 1200) but they cannot support 4K.

Being an analogue signal, the image quality can be affected on very long cables especially when there are external interferences. Choose high quality cables with good shielding and ferrite cores for best results or with cables over 20m.

Rating: 5/5

Also known as: DP

DisplayPort is a digital interface which was introduced in 2006 with a view to replacing VGA and DVI connections.
It is found on a few projectors but is more common on displays.

As with HDMI, there have been several versions of DisplayPort for hardware with the most recent ones being v1.4 (introduced in 2016) and v2.0 (introduced in 2019 and available in hardware late 2020).

DisplayPort cables are not classified by version.
All DisplayPort cables are compatible with all DisplayPort hardware, regardless of the version used in the hardware or the cable certification level.
That being said, different DisplayPort cables have different transmission speed support:

There is no maximum length of cables specified by the DisplayPort standard however according to the DisplayPort 1.2 standard, cables up to 2m must support HBR2 and all cables of any length must at least support RBR.
For lengths longer than 20m, we would recommend fibre optic DisplayPort cables.

Rating: 3/5

Also known as: Digital Visual Interface, DVI-I, DVI-D, DVI-A

DVI is used to connect a source such as a computer to a display device. Unlike HDMI it only transmits video, not audio.
There are three main types of DVI: DVI-A (analogue only), DVI-I (integrated – combines digital and analogue), DVI-D (digital only).

DVI also comes in two varieties: single-link and dual-link which has additional pins to increase the bandwidth.
Single link DVI is suitable for resolutions up to 1920x1200 at 60Hz while dual link will support resolutions up to 2560 x 1600 at 60Hz.
This means that a DVI connection will be fine for Full HD or WUXGA on projectors and displays, however it will not be suitable for 4K.

DVI cables are available in various lengths, up to 25m for good quality standard DVI cables or up to 100m for fibre optic hybrid cables. If you need to extend the signal further, there are DVI boosters and extenders available.

Rating: 3/5

Also known as: 3x BNC, 3x RCA, YPbPr, YCbCr

Component video is technically the name of an analogue video signal used in various interfaces but when it comes to AV equipment such as projectors or displays, component usually refers to a type of interface made up of 3x RCA (consumer) or 3x BNC (professional) connectors, typically coloured red, blue and green.

Component connectors are now rarely found on the latest AV equipment as digital interfaces are preferred.
Component can carry non-interlaced video and resolutions up to 1080i for YPbPr.

As with other analogue signals, the length of the cable and any external interference may affect the image quality so if using component, choose good quality cables.

Rating: 2/5

Also known as: S-VHS, Y/C, mini DIN

S-video is an analogue interface that carries the video data as two separate signals, luma (brightness) and chroma (colour), unlike composite video which carries (lower-quality) picture information as a single signal, or component video which carries (higher-quality) picture information as three separate signals, typically luma and two chroma components. S-Video was mostly phased out with the arrival of high definition video.

S-Video can carry 480i or 576i resolution video (standard definition video).

Rating: 1/5

Also known as: 1x RCA, Single phono, Cinch, CVBS

Composite is an analogue video signal and is the lowest quality interface found on AV equipment nowadays.
It usually is found in the form of a single yellow RCA connector or with two (red and white) audio RCA connectors.
It carries standard definition video as a single channel, up to 576i resolution.

Rating: 4/5

Also known as: 5x BNC, RGBHV

5x BNC connectors are a high-end alternative to VGA interfaces. They use 5 separate signals over coaxial cable, preventing crosstalk thanks to full coaxial shielding. They are found only on the higher-end equipment used for professional video applications.

Rating: 4/5

Also known as: HD-SDI, 3G-SDI

SDI is a family of digital video interfaces which includes HD-SDI, 3G-SDI, 6G-SDI and 12G-SDI.
The various versions support different bitrates and resolutions.

SDI is used for professional video applications like broadcasting and can be found on a few projectors.

Cables for SDI interfaces are one or more coaxial cables with BNC connectors like the ones used for 5x BNC although higher quality cables may be necessary for long runs at the higher bitrates.

Also known as: 3.5mm jack, headphone jack, audio jack, phone jack

The mini jack connector is commonly found on many projectors and displays to input or output audio signal, often in conjunction with a VGA video input (HDMI carries audio on the same cable).
Being an analogue connection, it can suffer from line loss and interference which will affect the sound quality, especially over long cable runs.

Also known as: 2x Phono

Many projectors and displays include 2x audio RCA connectors, usually as white and red plugs, alongside or instead of a mini jack input. They are often, but not always, associated with the composite (yellow phono) video input.
Like the mini-jack cables, 2x RCA is an analogue connection and can suffer from line loss and interference.

Also known as: Toslink

Optical audio is a digital interface which doesn't suffer from interferences unlike the analogue RCA and mini jack audio cables. However due to light attenuation, the lower cost plastic optical cables are limited in how long the cable can be before suffering from jitter or total signal loss. Higher quality cables allow for longer lengths.

USB is an interface used widely on many AV sources and displays for various functions.

There are several USB connectors available on electronic devices but the most commonly found on displays and projector are USB Type A (thin rectangle) and USB Type B (small square with 2 clipped corners) both version 1.0 or 2.0.

On projectors and displays, USB is often used for control and firmware updates, to connect a USB WiFi adapter, for PC-less presentation using an external USB storage device or even, on selected projector models, to display images via 3-in-1 USB display.
On interactive displays, USB is also used to allow interaction with your computer software from the screen surface.

Also known as: network, RJ45, Cat5/6/7

In most cases, ethernet connections are used on displays and projectors to connect the device to a local area network (LAN) to allow remote control and monitoring from a centralised office (e.g. in large office building or schools). It allows system administrators to turn on/off devices, check projector lamp usage, switch input etc.
It can also provide Internet access (if the network is connected to the Internet) for control from anywhere in the world or for Cloud content on signage displays, or simply to browse from an interactive display.
For some displays and projectors, network access allows users to display content from a remote computer.

Because Cat5/6/7 cables are better at carrying a signal over long distances, ethernet extenders are often used to convert HDMI or VGA to a network interface at the source and then convert it back to HDMI or VGA at the display side.
The newer the version of the cable, the higher resolution it can carry and/or the longer the cable can carry the signal.

Although HDBaseT uses the same 8 pin connector type and cables as Ethernet, it is different from Ethernet. It uses a different protocol to transmit a signal.

HDBaseT 2.0 transmits uncompressed UHD video, up to 4K at 30Hz with 4:4:4 colour coding or 4K at 60Hz with 4:2:0 colour coding. While it is useful over longer cable lengths, HDMI 2.0 is better if you want 4K at 60Hz with 4:4:4 colour.
HDBaseT will also carry an audio signal (it doesn't support ARC), Ethernet (100 MBps), power for power over HDBaseT and control signal.

If using a projector with a HDBaseT connector, you will need a separate compatible transmitter to convert the signal from the source.

RS232 also known as serial port is used for monitoring and controlling equipment remotely.
It allows commands such as turning equipment on or off, change video source, control speaker volume or check the status of the equipment (e.g. lamp life counter).

While Ethernet is now preferred for control and monitoring, RS232 is still widely available on AV equipment.

A 12V trigger input or output is usually in the form of a 3.5mm mini-jack connector and a standard 3.5mm jack cable is used to connect the trigger connectors between two devices.

A 12V trigger is used to integrate and automate equipment.
For example, to connect a projector to an electric projector screen so when the projector is turned on, a signal is sent to the screen for it to automatically come down without needing to use the projector screen's remote control separately. When the projector is turned off, the screen is then automatically retracted.
Some amplifiers/AV receivers have 12V triggers to automate more complex audio systems involving multiple devices.