Data and Video Projector Inputs

The different types of projector inputs

An extremely important but often overlooked consideration for projectors is the amount and type of data and video inputs that are available for use on the projector, and the types of video cables that are used to connect the projector to its input devices. While the technical specifications of the projector, like the contrast ratio or the type of lens, are the main factors that determine the quality of the image projected, a good video cable connection can significantly enhance the appearance of the image, and the type of connections available at the back of the projector will influence exactly what you are and are not able to connect up to it.

When considering what type of cabling to use, it is important to determine how you will be using your projector so you can purchase the type of video input cables that are best suited to your needs. This Bamboo AV Advice article will discuss all the various forms of video cables that projectors can accept, including composite video, s-video, component video, DVI, VGA, HDMI, USB and RGBHV. The advantages and disadvantages each type of cable offers will be considered, and we will also provide specific video cable recommendations for common projector applications such as home cinema systems and education classrooms.

Data and video inputs available on multimedia projectors

Every projector on the market is fitted with a varying number of “slots” or inputs which enable you to plug in a number of input devices such as laptops and computers. Nearly all projectors have a standard composite jack since composite video is the most common way to transmit video data. However, as technology advances more and more ways in which video signals can be transmitted have become available, these have, over time, been incorporated into the connection electronics of projectors. Potentially, projectors may offer more than eight different possible input connections. While our dedicated cables section will explain in depth the various cables and their associated inputs, this is a brief description of the possible video inputs.

Composite video projector cabling

The composite video cable is the most common and most rudimentary form of video input since it was the cable first used at the advent of colour television. Consequently it is not fully optimised to work with new LCD or DLP projectors, and it cannot transmit High Definition digital images. Even the standard definition pictures that composite video can broadcast are not rendered very sharply.

Composite video is formed from three coloured cables. The yellow cable is used to transmit the video signals and a combination of red and white cables is used to send the left and right channel audio data.

S-Video projector cabling

First invented in the 1980s, as the name suggests s-video (separated video) cabling differs from composite cabling in that it isolates the two types of video signals which would be combined on a composite cable. By separating the colour signals from the brightness signals (chrominance from luminosity), the colours are more clearly separated and the image will appear sharper. However, since s-video is still only an analog video signal it can only carry standard definition resolutions signals and is incapable of broadcasting HD TV. Furthermore, the white and red connectors still need to be used to carry audio signals, just like in composite video.

Component video projector cabling

Component cables offer a substantial increase in picture quality from composite because three separate red, blue, and green cables are used that are dedicated to transmitting the video signal. If these three cables are labelled Y, Pb, and Pr then the component cable can accept High Definition video, where as if the inputs are tagged Y, Cb, and Cr they will only output videos in standard definition. Regardless of whether the picture is transmitted in high definition or in standard definition, the image that will be displayed is of a much higher quality and colour saturation than component or s-video pictures. However, as with component and s-video, both red and white audio channel connectors are needed to transmit left and right audio channel signals.

DVI projector cabling

Digital Video Interface (DVI) cables were originally designed as a way to connect an LCD monitor to a computer. However, it has now become a common way to hook up audiovisual devices such as projectors, especially because DVI is capable of transmitting High Definition signals. DVI consists of a single video cable that is screwed into the back of the device in the same way that a VGA cable is. While this sounds simple, it is important to be aware that DVI cables only carry video signals, so you therefore need separate red and white audio cables to receive sound.

VGA projector cabling

This type of connection (Video Graphics Array) is most commonly used to connect computer monitors to computers. Due to the fact that nearly every laptop comes with a VGA output connection and that it is a simple one cable connection, VGA cables are often also used to connect laptops to projectors and HD TVs. However, like DVI, composite and s-video connections, VGA cables only carry video signals so a separate audio connection is necessary if sound is required.

HDMI projector cabling

High Definition Multimedia Interface is a type of digital cable recently developed specifically for the High Definition era consumer electronics products. If you wish to receive the best looking images on your display device then HDMI should be your first choice. It is the highest quality cable on the market since it incorporates both High Definition video signals and multi-channel Dolby digital audio. Furthermore, it is the simplest type of cable to set up since it is just a small, single cable and is readily available in lengths over 30 metres. HDMI is also the preferred choice of cable for Hollywood film studios since it includes High bandwidth Digital Content Protection (HDCP), which is used to prevent the pirating of high definition signals.

USB projector cabling

USB – or Universal Serial Bus is a type of computer cable system that was designed to allow many different types of devices to connect to computers. Nowadays USB devices such as portable hard drives and memory “sticks” can connect up to projectors as an easy means of transferring data without needing to use a laptop. USB was designed to replace serial and parallel ports and is frequently used for computer peripherals.

RGBHV projector cabling

RGBHV (which stands for Red, Green, Blue, Horizontal and Vertical) transmits separate red, blue and green colour signals and horizontal and vertical video sync signals to HD displays. RGBHV is sometimes found on higher end projector models but more commonly when connecting computers and monitors.

Projector input recommendations

Before you purchase the video input cables for your projector and the input devices it will use, it is extremely important to consider the situation you will operating your projector in and what requirements you have. Here is a selection of common situations and the recommended cables for each of them:

Home Theatre input recommendations

A home theatre set up is a situation where optimal image quality is of maximum importance. Due to the increasing popularity of Blu-Ray discs and HD TV, digital inputs are a necessity since analog cables are not capable of carrying High Definition signals. The minimum standard for home theatres should be component cables since this delivers solid High Definition and audio performance. A DVI connection will deliver a better picture but no sound will be transmitted so this cable is only recommendable if you have an external speaker setup. If you want to have the best possible audio and visual performance, as well as the simplest setup, HDMI cabling should be used since it incorporates high definition video signals and 5.1 surround sound audio signals.

Corporate and Education input recommendations

While High Definition video output is a nice extra, in a corporate environment the image quality is perhaps not of top priority. Productivity and efficiency is usually the number one goal, meaning that VGA connections are often the most recommendable type of cabling since it is currently the most widespread type of video connection and consists of only a single cable. Furthermore, since every laptop ships with a VGA port installed it is a far simpler process to connect a laptop to a projector with a VGA cable than a composite cable. The only drawback is that no sound is transmitted, however this often is not a requirement in corporate situations.

We hope that this Bamboo AV Advice article has been useful to you!

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