HDMI sockets are appearing in a whole host of products. But this high-definition capable, multipurpose digital connection means more than just fewer cables wrapping around your TV stand. Here's what you should know to get started.
What is HDMI?
HDMI stands for high definition multimedia interface. It's a medium-sized 19-pin connection that's becoming standard on a range of audio-visual products. For TV, DVD and game playing it takes over the function of the Europe-wide SCART socket by carrying sound and pictures simultaneously. Unlike the SCART, HDMI uses digital signals throughout. It can also replace separate digital audio connections, such as optical or coaxial leads. In theory this makes your AV system simpler to link together.
Like its name suggests, HDMI can deliver high definition pictures and multichannel digital soundtracks. It can also carry some standard definition formats, which is useful in the case of HDTV receivers, because not all programmes are shown in HD or with 5.1 surround sound.
HDMI is also used by 'upscaling' DVD players, which take standard DVDs and use digital processing to produce an HDTV-like output. These players can cost as little as £60, so even if you don't get HDTV broadcasts or own an HD DVD or Blu-ray disc player, you can still benefit from HDMI.
Of course your TV will also need an HDMI input - preferably more than one to allow for additional items at a later date. If you run out of available HDMI inputs you can get switch-boxes for connecting more than one HDMI product and swapping between them. One, two or more HDMI inputs are now standard on most new flat-panel LCD and plasma TVs as well as rear-projection TVs and standalone video projectors.
Does HDMI always mean better quality?
Having HDMI does not guarantee that the product can show genuine HDTV (at least 720 progressively scanned lines or 1080 interlaced lines) because some displays convert to a lower native resolution. Look for an 'HD Ready' logo to confirm HDTV compatibility.
Similarly, using HDMI does not guarantee a better performance. In the majority of situations you will get a superior result compared to analogue connections such as S-Video, RGB and component video, but some standard definition digital TV channels or DVDs can look worse when spewed digitally onto big high-res screens, especially if they use heavy compression (here it's wise to switch temporarily to analogue component video if you're fussed). However, with more HD broadcasts and discs becoming available, it's getting easier to make ropey old pictures a thing of the past.
Are there different versions of HDMI?
Yes, like the humble USB ports on your PC, there are different standards of HDMI. As with USB, products using newer standards of HDMI can be plugged together and are 'backwards compatible' with earlier flavours of HDMI, so you shouldn't be left facing a blank screen and silent speakers.
The HDMI spec is currently at version 1.3. This offers a few optional enhancements over older versions, notably more accurate colour reproduction, faster frame rates and lip-sync correction to prevent that 'loose lipped' problem that happens when the sound runs out of step with the image.
To take advantage of the new features your source machines and TV or projector must all be fully compatible with the latest HDMI version. This also includes any surround sound amp or receiver that might be connected via HDMI in your system. Products with HDMI v1.3 are becoming more widely available during 2007, such as Sony's PlayStation 3 and Toshiba's HD-XE1 HD DVD player.
Only a few current HD-ready TVs will accept the new features that come with HDMI v1.3 and, to date, just a small number of amps and receivers are fully compatible but that will change in the coming months. Good quality cabling is also important to take full advantage of the increased bandwidth of v1.3.
HDMI will continue to develop, including a possible 29-pin variation of the socket, so you might have to consider replacing equipment if you want to keep up with every future enhancement, much like the PC sector. You can get a great performance from a decent system connected with HDMI right now though, so don't let that put you off.
Aren't HDMI cables all the same?
It's long been known that better quality cabling can minimise signal loss and distortion in the analogue domain, both in sound and picture. Although digital systems are generally more robust due to technologies such as error correction, signals can still be influenced by variations in the quality of the cable or affected by interference.
Basically, if you've spent a small fortune on your player, amp and TV, it makes no sense whatsoever to skimp on the cabling. Higher grade HDMI cables are especially important for carrying the highest resolution video, which uses 1080 progressively scanned lines, also known as 1080p, but in the future products could increase this to 1440p. If you want to connect across a long distance - to a ceiling-mounted projector for example - then you'll definitely need a high-performance cable.
Cables
Three to try
QED - Qunex HDMI-P
A good HDMI option at a reasonable price, it's certified for the latest v1.3 spec and supports full bandwidth 1080p video up to 7m. Available in 1-15m lengths, priced between about £40-£200.
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Better Cables - Silver Serpent
This resilient reference-quality, v1.3 compliant HDMI cable is offered in 1080p-capable lengths from 0.5-15m, priced from around £35 to £230.
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IXOS - XEN XHT658
A top-of-the-range silver-plated HDMI cable that delivers 1080p video up to 11m and available in lengths from 1m (£110) to 11m (£280).
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