The expectation has been building for years, the TV sets have been heavily promoted in stores for months, and now the UK’s 21st-century television revolution is finally with us. Early adopters will see this summer’s football World Cup and Wimbledon championships in HDTV, with the likes of BBC, NTL, Telewest and Sky all focusing their attention on the biggest broadcasting breakthrough since the first colour transmissions in 1967.
No written description of HDTV can bring the technology to life – you just have to see it in action. Increasing the resolution to 1,280 x 720 or 1,920 x 1,080 (the two standard HDTV formats) unleashes some major enhancements: the image looks clearer and brighter; colour graduations are smoother and more realistic; you can see more intricate forms or textures. The image looks both more lifelike and more cinematic. Some compare it to looking out of a clean window, but here’s something easier to grasp – it’s like comparing an image taken with a 1-megapixel digital camera to an image taken by a 2- or 4-megapixel model. You’re getting between double and four times the detail.
And, in theory, the PC is perfectly equipped for this. Most of us have displays capable of a 720p image (more on this later), even if we use a 1,280 x 1,024 TFT monitor or a 1,280 x 800 laptop. What’s more, HD content is already available, from downloadable demo clips to HD trailers on Apple’s QuickTime site. With the right software – Windows Media Player 10 or QuickTime 7 – we can enjoy video recorded in the H.264 and WMV 9 (Windows Media Video) HD formats, and most recent graphics cards from Nvidia and ATi have listed H.264 acceleration among their features. Both HD DVD and Blu-ray PC drives are on their way, and we even have HD digital video cameras capable of shooting 1080i resolutions. What’s more, Avid, Pinnacle and Ulead have produced HD editing software to match.
But HDTV, whether for your television or your PC-connected widescreen TFT, is a minefield, and there will be winners and losers from television’s HD revolution. From the recording studio, through the broadcast network and into your living room or study, every link in the chain must be ready.
As well as the tremendous increase in resolution, HDTV also promises a more stable image, and it’s important to be clear about the different terminology. The old CRT televisions were built to handle an interlaced picture, where the image was converted into two fields of odd and even lines that alternated 50 times per second, fooling the eye into perceiving a single 25fps image. The problem is that the eye isn’t that easily fooled – it notices the slight flicker, and registers unnatural motion. 100Hz sets were designed to fix this, but the digital processing required often resulted in noticeable digital artefacts, particularly in sequences with lots of fast movement.
The LCD and plasma screens that make up the bulk of HDTV sets use a different system, called progressive scan. Here, the whole image is updated one frame at a time at a constant 25fps or 30fps. As a result, HDTV is designed to run in three formats: 720p (1,280 x 720 pixels, progressive scan), 1080i (1,920 x 1,080, interlaced) or 1080p (1,920 x 1,080, progressive scan). Which you use will depend on first, your set, and second, the resolutions supported by your broadcaster or source equipment. Basic HDTV sets may support only720p or 1080i; most current HDTV broadcasters in the US broadcast only in 720p or 1080i; the Xbox 360 games console outputs only 720p or 1080i, and the same goes for the next-generation HD DVD format. However, both the Blu-ray format and the PlayStation 3 console are expected to support 1080p. Perhaps that’s why Sony, which produces both, is so keen to describe 1080p as the true high-definition format.