Stuff's guide to HDTV

Thanks to the hi-tech wonders of high-definition video, you can have unbelievably clear, highdefinition pictures that are almost film-like, making standard-definition broadcasts look positively blurred by comparison — that is, if the humble viewer can navigate a mire of confusing tech terms.

HD EXPLAINED

High-definition (otherwise known as HD) video is all about image quality. In screen terms, this relates to the amount of pixels (the coloured dots that make up a picture) able to be crammed on to a screen. Simply put, more pixels equals a higher-resolution picture.

In HD-speak, this is measured by the number of horizontal rows of pixels able to be displayed.

Today’s standard-definition tellies display 625 horizontal lines of pixels — the two most common HD versions can display an impressive 1080 (which is called either 1080i or 1080p), or 720 horizontal pixels (720p or 720i), which makes for far more detail and significantly crisper, almost three-dimensional, on-screen images. In HD parlance, the “p” or “i” refers to how pictures are drawn on the screen (either using progressive — that’s the “p’’, or interlaced scanning, which is the “i’’).

Progressive-scan screens (720p and 1080p), completely redraw each horizontal line of pixels from top to bottom, whereas interlaced screens (720i and 1080i) first redraw odd-numbered horizontal lines and then even-numbered lines. Because progressive scan screens refresh the entire screen in a single pass, video tends to be smoother and cleaner, making a huge difference for watching fast on-screen action.

Most HD tellies are wide and have a screen ratio of 16:9. This means they measure 16 inches horizontally to every nine inches vertically to deliver a rectangular, cinema-like experience.

Older, standard-definition sets are typically 4:3 and will cut the end off both the left and right-hand sides of widescreen broadcasts and DVD movies (some TVs can, however, shrink the on-screen footage to deliver a postbox-slot effect, resulting in a narrow image with dark bars top and bottom).

BROADCAST HDTV

For most of us, our first real experience of HD is likely to come in the form of broadcast HD TV when both Sky and Freeview launch HD offerings this year. Both are using slightly different broadcast methods, but in both cases the results promise to be stunning.

Freeview’s HDTV offering will not require any ongoing subscriptions and is set for an April launch. The service is to be broadcast over old-school terrestrial UHF, using digital technology to deliver the HD goods. This will mean that just like in the old days, you’ll need a UHF antenna on your roof, pointed in the right direction, before you’re able to receive a HD Freeview signal.

In addition to a UHF antenna, you’ll also need a new Freeview HD compatible set-top box (existing Freeview boxes are not HD compatible). Several intriguing Freeview HD set-top box options also loom large. In Britain, Sony has launched PlayTV, an HDTV tuner add-on for the PlayStation 3, and the rumour mill is running hot that it will soon launch in New Zealand. Industry sources are also confident that many LCD and plasma screen manufacturers will also integrate Freeview HD tuners into their latest crop.

All this sounds fantastic (and it is), but there is one gotcha — Freeview HD TV will be broadcast only in New Zealand’s metropolitan centres and won’t be available to most rural viewers. Freeview’s general manager, Steve Browning, is, however, confident “that coverage should reach 99 per cent of suburban homes in the main centres’’.

Freeview will initially broadcast three channels in HD, with both TV1 and TV2 broadcasting in 720p HD, and TV3 has yet to confirm what HD resolution it’ll go to air with when the service launches in April. Programmes will have to be filmed in HD and you’ll need an HD-capable TV set to see the improved picture.

NEXT-GENERATION DVDS

Another option for those who can’t wait till next month for broadcast HDTV is buying a next-generation, HD-capable DVD player. Until recently there were two competing next-generation DVD formats, Blu-ray and HD DVD.

Unfortunately, both HD disk formats are incompatible with each other, and both format supporters have spent billions of dollars fighting a battle to win the hearts and minds of consumers for their version of the next-generation DVD.

However, most consumers (many of whom got burnt in the VHS v Beta format war) have stayed away, being wary of buying a next-generation DVD player that can play only half of the world’s movies.

Only a few months ago, there was a major shift in the war when Warner Brothers, one of the world’s biggest movie studios, announced it would only deliver movies in Blu-ray instead of HD DVD.

The protracted format war is effectively over, with Toshiba and Microsoft both dumping HD DVD last month. There is only a handful of Blu-ray movies available locally but this will change.

Thankfully there is a third alternative, in the form of upscaling DVD players such as the Oppo 971 or Sony’s PlayStation 3 (which also includes a Bluray player). These take a standard-definition DVD and use clever video processing to display them in glorious HD.

Not only are the results of upscaling usually impressive, it’s a great way to extend the life of large collections of standard-definition DVDs.

LCD v PLASMA v CRT v PROJECTION

There are different types of HD sets: projection, plasma, LCD and CRT. Each has disadvantages, but they’re all good sets. Projection TVs are bulkier than plasma and LCD. You can’t mount them on a wall.

Projection sets are relatively inexpensive. Digital light processing (DLP) models are the most common type. You’ll also encounter LCOS (liquid crystal on silicon), LCD (liquid crystal display) and CRT (cathode ray tube). With DLP, you may notice a rainbow effect. Check the TV carefully before buying.

Plasma and LCD sets are wall-mountable. Both historically have had drawbacks, which have mostly been solved or mitigated. LCD sets are lighter than plasmas and consume less power. Until recently, they had problems with smearing — motion appeared blurry.

Newer sets are less likely to have the problem. Response time is important. This is the time it takes for the pixels to turn on and off. Aim for an eight-millisecond (or less) response time.

Smearing is less likely with fast sets. Black levels are sometimes a problem with LCDs. Gradations of black can be difficult to see in dimly lighted shows. Smaller LCDs sell for well under $1000. Larger models are more expensive than plasma sets.

Some people consider LCDs superior to plasmas. But plasmas have beautiful pictures. The smallest plasmas are 37 inches. If you need something smaller, shop for an LCD.

Reflections are a problem with plasma sets. They work better in darker rooms. Historically, they’ve also suffered from burn-in — a static image displayed too long would become permanently visible on the screen. This is less likely with newer models.

CRTs range up to 36 inches. These look similar to traditional televisions. Many say CRT sets offer the best picture. But this technology is dying. Why? CRT sets are massive. The tube can be 61 centimetres deep on large sets. Some weigh about 90 kilograms.

 

- © Fairfax NZ News