RF coaxial
This is the same as TV aerial cable. Digital set-top boxes and VHS and DVD recorders normally carry them to take a TV aerial signal and pass on to a TV. Many also output picture and sound via RF (radio frequency) but the picture and sound quality are basic.
Composite video
A general-purpose connection using a single phono socket (normally coloured yellow), it is also carried via Scart leads (see S-Video and RGB for more on Scarts). Composite is used by almost every AV device but it is one of the poorest, suitable for VHS playback at best due to fuzzy outlines with fine detail. Don't use for digital TV or DVD unless there's no alternative.
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| QED Qunex S-VS
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S-Video
This uses a small dedicated socket or a Scart - if your player/digibox's Scart can be switched to S-Video and if your display accepts it. S-Video separates colour and detail information, minimising the interference seen with composite. Most TVs, projectors and AV amplifiers use S-Video. It does not carry sound, so if you are not using Scarts (which include sound) you must use analogue or digital audio outputs, depending on your system. Scart-to-S-Video socket adaptors are available.
RGB
This newer system is now a default output on European DVD players and digital TV boxes. It is almost exclusively sent via fully wired Scarts but some DVD players and plasma screens use four phono or BNC sockets.
Basic TVs often have only one RGB input, so if you have both digital TV and DVD, you'll have to compromise - usually with S-Video for DVD, because S-Video is rare on digiboxes. Better DVD recorders also have RGB Scart inputs but many only have S-Video input, so your digibox must output S-Video or you are otherwise left with poor quality composite.
RGB is one of the clearest analogue connections, slightly better than S-Video. Scart sockets also include widescreen switching signals to prompt TVs to adjust to the correct setting.
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| QED Signature CV Component Interconnect QE
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Component video
Once an elite connection for the best analogue link, component video is increasingly common on DVD players and many TVs. It is also a fixture of home cinema plasma, LCD and projectors. It's a video-only format delivered through three phono leads (coloured red, green and blue) and closely related to RGB. The difference is negligible in normal interlaced video operation, however, component sockets also carry progressive scan, which gives more solid and cinematic results. Most plasmas, LCD TVs, projectors and a growing number of luxury tube TVs accept progressive scan in both European PAL as well as NTSC (USA and Japan) standards. Some displays and projectors convert from interlaced to progressive, so component video is not always necessary but the connection is more robust and less prone to interference compared to Scarts.
DV
The DV interface, also known as i.Link, is used to connect digital camcorders to DVD and hard disk recorders or PCs for transferring and editing. It is a high-speed, all-digital connection but it's not used for home cinema applications.
DVI
The DVI (digital visual interface) has evolved from the PC sector to become an all-digital video link from high-end DVD players to digital displays such as plasma, LCD and projectors. Products are still scarce but growing in quantity. Unlike PCs, for home cinema, DVI products must be listed as HDCP compliant (High-bandwidth digital content protection) or the two devices may not work together.
HDMI
The newest AV system is related to DVI but includes additional capacity for audio and 'handshaking' between machines to set the best AV modes automatically. For this reason HDMI (high definition multimedia interface) is being dubbed the 'digital Scart'. Although it's as small as a USB socket, this pure-digital interface is set to become widespread. HDMI v2 is will follow later to expand the system's digital stereo capacity to full multichannel audio in one link. Leads to connect DVI to HDMI (video only) are also available.
Summary
Although systems such as component, RGB and S-Video are not digital, they are acceptable for standard definition TV and DVD, especially on smaller screens or via good quality cables. However, remember that high definition broadcasting and HD-DVD will inevitably arrive in Europe so if you want future-proofing, look for HDCP-compliant DVI or and HDMI inputs to get better image quality and control.
