As more and more big box televisions reach the end of their natural life, they are being replaced by their sleek LCD or plasma cousins. Sure, these flat screen TVs are slim and stylish – especially the new LED based sets - but the big sell is the high definition 1080 pixel display. So how hi is your def?

Dedicated A/V specialists and technology obsessives already know all this stuff, but for casual consumers the whole business can be rather confusing.

Below, without resorting to any confusing technobabble, is my attempt to rank the available media for your skinny new telly in approximate order of wow-factor.

Blu-ray
Top of the definition charts, at least for the next few years, is Blu-ray. Sony’s high-definition digital disc format beat out the rival HD-DVD standard, ending Sony’s 30 years of hurt over the defeat of Betamax. It delivers full 1080p resolution, meaning every pixel on your screen is getting its own unique instructions, so the TV is working as well as it possibly can.

The discs are capacious enough that lots of extra content can be poured on alongside the extra-sharp pictures. For example, if your weakness is for checking the trivia on IMDB while you’re watching a movie, recent Fox releases will display nuggets of information about cast and crew directly on your screen if you have a web-enabled player. With an already huge user base and some neat little firmware tricks coming soon, the Blu-ray format will be with us for many years to come.

Sky HD
Sky was for a long time the only broadcaster offering high definition pictures in the UK. The images are 1080i. Without getting too deep into technical detail, it’s almost as pretty as 1080p, but not quite. On screens below 40 inches you will struggle to see the difference. Many Sky HD shows are broadcast with 5.1 surround audio, which makes all the difference when you’re watching music or movies, although of course you will need a surround amp and speaker setup to enjoy the glorious racket.

If you sign up for one of Sky's movie packages, it's more or less the equivalent of someone popping round with a box of Blu-ray disks every night.

Not all Sky channels are HD, of course, but at the moment it offers about 80 per cent of its movie channels, some specialist channels including Sky Arts and a few forward-thinking networks such as FX-HD. You can still watch regular channels on a SkyHD box, but they aren’t HD.

iTunes downloads
If you have a suitable computer connected to your TV, and you have a reasonably nippy broadband connection, you can buy or rent HD movies and TV shows from iTunes. Because the compression ratio is higher, pictures are less hi-fi than Blu-ray. Again, it’s not something you’re likely to notice unless you have an absolutely monstrous screen. As an entertainment medium, this method is likely to remain rather niche for a few years yet.

Freesat HD
Comparatively new, and still something of an unknown quantity for most telly watchers, Freesat HD offers very similar audio and picture quality to Sky HD. Not to be confused with the near-ubiquitous Freeview, which operates through a standard television aerial, Freesat requires a satellite dish and a special set-top box. Once you’ve bought the kit, Freesat is, as the name suggests, free. The range of HD channels is a little limited right now. How well it grows depends on whether there are enough telly addicts who want more than Freeview has to offer, but are unwilling to stump up for a Sky subscription.

DVD
Ignoring for the purposes of clarity any fancy upscaling tricks that can be done by recent-model players, DVD isn’t strictly HD. It’s just very clear standard (480) definition. That isn’t to say that DVD playback doesn’t look great anymore. It was good enough for most of us a couple of years ago and the DVD format has been so popular it will be a long time before we see the end of this versatile and convenient format.

Freeview and Sky
Standard definition Sky packages and Freeview are sufficiently similar in terms of overall quality to be addressed together. Because of the way that frequency ranges are divided between channels there are some minor differences – for example ITV looks distinctly sharper on Freeview than it does on Sky – but the only genuine difference is in channel choice: generous on Freeview, positively overwhelming on Sky.

Broadcast TV
The old-fashioned telly we know and love. Does tend to look rather grainy on modern TVs, mainly because it is a square (4x3) picture rather than a cinematic (16x9) one and therefore suffers all manner of indignities on widescreen sets.

VHS
The videotape format is still alive, despite rumours of its demise. The last standalone JVC VHS-only unit was produced on December 31, 2008 and you would probably struggle to find one to buy today, but tapes are still available and there is even a twin-deck Blu-ray / VHS combo available, if you can think of a use for it.

YouTube
Don’t be fooled by the little red HD button, most video that is encoded for YouTube and similar flash-based players is technically pretty horrible. Quite funny, as often as not, but horrible.

NOTE: Apple's downloads are, we are now informed, 720p. We apologise for the error.

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