Glossary

A simple glossary, which will be updated over time, to give a hopefully simple explanation of the many audio-visual terms which CVP Oxford may refer to.

Aspect Ratios and resolutions

Aspect ratios correspond to the ratio of the width of a screen to the height. Media (films, powerpoint slides etc) look best when they are shown on the correct shape screen.

Films are normally shown in widescreen format on retail media (DVDs, Blu-rays).

When showing media on the incorrect shape screen, there are a number of options.
Stretching the image to fill the screen. This can result in a distorted output as the image is not being shown as it was intended.
Leaving black areas. This used to be common on TV when films were shown with black areas at the top and bottom, and was referred to as letterboxing. (The image is wide and short, like a letterbox).

Computer resolutions follow the same aspect ratios established initially be the TV industry. A 1024 x 768px computer resolution is a 4:3 ratio, while 1920 x 1080px (1080p or full HD) is a 16:9 ratio.

resolutions
Image taken from Wikipedia, used under creative commons licence

In this image, all the resolutions is RED are 4:3 images, while the BLUE resolutions are 16:9.

If you are booking a projection screen, monitor, projector, or similar from CVP, please let us know what you will be using the equipment for, so that we can better help you to get the best result.

 

BNC

'BNC' describes the connector only, not the type of signal it carries. It is typically the more 'industrial' version of domestic phono cables, as it locks into position. BNC cables are used to carry composite, component, and VGA signals among others.

Transmitting a VGA signal via BNC cables requires five cables, which carry seperate parts of the image and timing data. The benefit of this over VGA cables is that they can be easily extended if required and may suffer less degredation. However, the need for multicore cables result in more expensive cable runs. In most situations there is no apreciable difference.

Some equipment (typically switchers) may have five BNC connectors in order for you to connect any type of analog signal, by using one, three or five of the sockets. This obviously saves space on the unit where multiple types of sockets are not required, however some adaptor cables may be required.

 

DisplayPort


The center divider in a displayport socket is shaped like a long 'n' and the socket is flat on one end.

A multi-purpose connector, although as the name suggests, primarily disigned for displays. This is an intended replacement of VGA and DVI cables, and supposed to be used in parallel with HDMI.

It can be used to carry audio, video, or both. The data type is not backwards-compatible with DVI or HDMI, however some of the more recent versions can be switched to produce this feature using an adaptor cable.

These connectors are commonly found on computer monitors, computer graphics cards and some professional screens.

It is expected that as computer manufacturers stop including VGA, this will be the replacement video connector.
Although having said this, Apple already currently uses the mini-displayport in many of its products.

The mini-displayport is physically smaller and is almost exclusively found on apple products. Apple (and some 3rd parties) sell adaptors which can convert this output to VGA, DVI, HDMI etc. These have to purchased seperately to the device, and would be needed to connect it to any non-apple technology, the vast majority of which does not accept mini-displayport signals.

Please note that CVP does not stock displayport adaptors for external use. Due to the nature of the connectors and ports, there are so many permutations that it is unfeasable to stock every option. If you intend to use your displayport or minidisplayport device (which has no other visual outputs), please ensure you have the correct adaptor to use with the setup we or someone else may be providing. ie projectors etc.

DVI


DVI cables and sockets are almost always white. The '-' on the right may be '+' shaped.
This donotes different types of DVI.

DVI carries visual information only. There are multiple types, which may carry digital as well as analog signals. DVI is capable of transmitting higher resolutions than VGA, which it attempted to replace.

The digital signalling is the same of that of HDMI, therefore HDMI to DVI adaptors are available. However, DVI is not able to carry the audio data that HDMI can.

The DVI-I version of DVI (integrated) allows the transmission of VGA signalling over DVI. This further cements DVI as the hopeful replacement to VGA, which was then itself superseeded by HDMI.

These connectors are commonly found on computer monitors, computer graphics cards and some professional screens.

HDMI


An HDMI connector is flat on the top, with two indents on the bottom. The center divider is flat.

HDMI is a common connector for High Definition (HD) cabling. Widely adopted domestically, all HD TVs will have one of these connectors. They transmit audio and visual information in one cable, and can do so at a high resolution.

HDMI is somewhat backwards-compatible with DVI, using the same visual data mechanism. This would, however, require the audio to be delivered seperately.

It is possible (and frequent) for HDMI to be encrypted, in order to restrict the use of copyrighted material. (Typically dvds and blu-rays.) This may introduce problems when using HDMI with larger systems, in which all of the components must be HDCP (HD copy protection) rated.

SCART

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Still found regularly on DVD players and TVs, this was a multi-format connector first pioneered in the 1970s. It carries video and audio, while the video can be in RGB, composite, or s-video formats.

SCART adaptors are common, and allow it to be broken into seperate video and audio signals.

Widely being replaced by HDMI in consumer electronics, although most TVs will still have SCART to allow use with older DVD players etc.

VGA

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VGA sockets are almost always blue. They have 15 pins.
Sockets with 9 pins are probably serial ports, and cannot be used to output video.

Commonly found on PCs, projectors and monitors. This transmits only image information, and is analog.
It is being phased out slowly from 2012, and replaced with digital versions, including HDMI, DisplyPort etc

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