DVD - The bigger picture

Digital Video Disc is now almost impossible to ignore. Most new PCs come with DVD as standard and a few years from now the humble CDRom will seem about as exciting as a floppy disk. But what is this new medium, and how does it work?

You'd be hard put to tell the difference between a DVD and a CDRom just by looking at them. Both are shiny, five inches in diameter and packed with digital information which won't wear out. But DVDs have one big advantage - you can fit much, much more onto them, indeed up to 25 times more information than you can get on a CDRom.

There are two ways to get DVD on your machine. Buy a PC with a DVD drive, or buy a DVD drive and fit it into your existing PC. Even a PC priced at around £1000 will come with a DVD drive nowadays. And if it doesn't, we'd recommend that you ask the supplier to fit one. It's a lot easier and cheaper to get the manufacturer to fit a DVD drive, and companies that sell direct to buyers will happily do this for you.

While it makes sense to buy a new PC with the latest technology, should you upgrade your existing PC? At the moment, there's not a lot of incentive for PC users to replace their CDRom drives with a DVD drive.

Programs haven't become so complicated yet that they need to make use of the larger capacity you get on DVDs. And when they do, it's likely that your current PC will simply be unable to cope with such a gargantuan program. It's more likely that games and multimedia titles will be the first to take advantage of the format.

What you can also do with a DVD drive is use it to watch DVD movies. If you're one of the many who aren't ready to fork out for a TV set-top DVD player that won't even let you record, but still want to watch the latest DVD releases, then this is a big incentive to upgrade. Of course, if your CDRom is on the blink, then it could be a good opportunity to replace it with the latest technology. Make sure your PC can handle it though.

A tight fit
How can they squeeze so much information onto a DVD? The answer is simply with miniaturisation. If you looked at a CDRom with a microscope you'd see that the surface is punctured by shallow indentations, known as pits. These hold the digital information that's read by the laser.

On a DVD, these pits are much smaller and much closer together allowing many more of them to be etched onto the surface of the disc thereby providing the room to store that much more data. A new type of laser is required to read these finer tracks, which is why you'll also need a DVD drive to play the discs.

A CDRom can store around 650Mb of information, which sounds impressive until you discover DVD starts off with a whopping 4.7Gb. DVDs can also use both sides of a disc, doubling their capacity to 9.4Gb. Even better than that is a particularly cunning technology which actually places a semi-transparent layer on top of the surface of the disc. By refocusing the laser beam between these two layers, you can almost double the capacity again. Do this to both sides of the disc and you're up to a massive 17Gb. You have to flip the disc over yourself, but that's only a minor irritation in the circumstances.

Digital killed the video star
Two things are really driving the DVD format. PCs, where the new drive has replaced the CDRom drive, and - the big clincher - movies, where it looks like DVD may replace VHS video tapes altogether. Today you can walk into most big video rental stores and take out a DVD movie, and, of course, the picture quality is much better than VHS.

230,000 DVD players were sold in the UK last year. There are two types: those that you get in your PC, and standalone players which sit with your TV rather like a video recorder. With trends in the US being quickly followed in the UK, it's worth noting that 3.9 million DVD players were sold in the US during the same period.

The rental market is treating both formats equally, with nearly every new film being released on both VHS and DVD at the same time. The back catalogue of movies is quickly reaching VHS levels too. Today there are more than 1300 DVD titles available in the UK and more than 4000 in the US; four million DVD discs were sold in the UK last year and 21.4 million in the US.

The majority of DVD players worldwide are inside PCs, however. Unsurprisingly, DVD movies come with content that make the most of computer technology, such as point-and-click pages and links to websites. But you'll find other extras stuffed onto these high-capacity discs. It will vary from title to title and some movie distributors are more stingy than others, so check out the contents before you buy. The sort of extras that are enticing people over to DVD are out-takes, behind the scenes shorts, directors' commentaries, filmographics, music videos and soundtracks.

Better yet, most DVD movies cost less than £25, and many are between £15 and £20. Okay, that's a few pounds more than a VHS movie, but the difference in quality and extras is incomparable - remember you can instantly pause or skip tracks just like a CD, and you'll never have the bother of rewinding them.

The big squeeze
DVDs may be able to store loads of information, but believe it or not there's still only room for about five minutes of plain digital video. In order to squeeze an entire movie onto the disc, the DVD must shrink or compress the video using a system called MPEG-2. The sound is also compressed on DVD movies, and the most common system used is Dolby Digital.

MPEG-2 (also used by digital TV) squeezes more than two hours of video onto a single-sided, single-layer DVD and still looks great. Many movies now come on dual layer discs, which gives the video even more room to breathe, allowing for better quality pictures and/or additional extras. Then there's the double-sided discs, which can be used to hold a widescreen version on one side (where the movie appears in landscape format, as it would on the big screen) and a full screen version (without black bars top and bottom) on the other.

Compressing video and audio is all very well, but you'll need to convert it back again to watch and hear the movie at home. A home DVD player has such a decoder built in, while PCs have to do it either with a special internal card (hardware DVD decoder) or a program (software DVD decoder). On the PC side of things, you'll also need a DVD drive, as CDRom drives cannot read DVDs.

All things not being equal
Not all DVD drives are the same. The very first ones couldn't read CD-R or CD-RW discs for example, and it's only the very latest examples which can play re-recordable DVD-RAM discs. It's hard to tell exactly how old a drive is, but models built in the last six months that are labelled as being faster than 6-speed (on the box it will read as 6X) are likely to be compatible with most formats. Note that a 6-speed DVD drive will also spin CDs at 32-speed or faster.

You don't just need a DVD drive to watch a movie on your PC - you also need a DVD decoder. Previously, you'd need a separate hardware DVD decoder card, but today's PCs are getting so quick that they can actually do it themselves, simply using software. Decoders are also often referred to as players, so don't get them mixed up with the drive itself. Most PCs sold with DVD drives come with software DVD decoders installed.

As the decoders cost from just £15, these are a great way to try out DVD movies on your PC. For perfectly smooth results, the manufacturers recommend using at least a 300Mhz Pentium II chip, but we reckon you may need something running above 400Mhz to ensure a glitch-free picture.

We tried two software DVD decoders - MGI's SoftDVD Max and InterVideo's WinDVD - which both produced great-looking pictures and left nothing to choose between the two. WinDVD is given away with Creative Labs' SoundBlaster Live cards, while SoftDVD Max (which works with a wide range of graphics cards) can be downloaded from MGI's site - www.dvdmax.com - for about £15. You'll also find that many 3D graphics cards are supplied with software DVD decoders for free. If you have a slower PC, or want guaranteed results, then consider a hardware DVD decoder card.

Rather than being an overnight revolution then, DVD is something that is going to quietly take over. In fact it has already crept into many PCs, replacing conventional CDRom drives. But there's no skirting the fact that movies are the real driving force behind DVD. We know that you didn't buy your PC to watch movies on, just like you didn't buy it to play games on, but it does round things out nicely.

DVD recorders
Standalone DVD players aren't going to replace VHS video recorders until they can also record video. Remember the old Betamax and VHS video standard battle back in the 1980s? Well, it looks like we're in for another fight. These formats are the same as the ones battling it out for dominance in your PC.

You can expect DVD video recorders - costing around £2000 - to reach our shores by the end of this year or the beginning of 2001. Early adopters will not only be paying a premium for the new technology, they'll also have to gamble on a format. The eventual winner may not even be DVD. There are devices being touted in the US that use large hard disks. With random access these will let you begin to watch a programme while it's still recording - great if you come in five minutes late and don't want to wait until it's finished.

Home DVD players
Watching DVDs on a PC is all very well, but do you really want to wait for the machine to start up in the first place, whirr noisily in the background, then possibly crash halfway through the movie? Despite the lack of a record button, standalone DVD players do have their advantages. They will switch on straightaway, run quietly, boast the convenience of a remote control and never crash.

Standalone DVD players will also happily play your music CDs, although only the latest will read home-made CD-R compilations. Prices start at £250 and are likely to drop further. However, you get what you pay for and decent models have remained at around the £500 mark. Enthusiasts may wish to spend more, and players are available at £1000 and more.

Apple and DVD
Apple has boasted DVD facilities on its Macs for some time now, but is currently experiencing some issues that users or potential buyers should be aware of. PowerBooks, and older G3 Macs equipped with DVD drives, use dedicated hardware to decode the video. On the G3s this was a small card which clipped onto the standard ATI 128 graphics card, but sadly Apple no longer sells this part.

Owners of non-DVD G3s need not fret however, as the latest version of Apple's software DVD decoder can make use of the ATI 128's motion compensation to help decode video, which means all they'll need to do is replace their CDRom drive with a DVD. Alternatively, several suppliers like MyGate and Jigsaw sell bundles consisting of a PCI decoder card and DVD drive for a complete G3/G4 solution costing about £200.

The latest G4 Macs and iMac DVs have DVD drives built in as standard, and Apple reckons they're sufficiently fast to decode DVD video using software alone. However, many of these systems were sold with a preview version of the software player and quite a few users complained of problems - the most common being that the sound was going out of sync with the picture after only a few minutes.

Rival recording standards
People are never satisfied - you tell them about a great new playback format and the first thing they ask, is when can they record on it? DVD recorders will be available shortly, although if you've lots of money and can afford a trip to Japan, you could buy one now. The problem is that there's more than a couple of recordable technologies out there, all vying for your hard-earned cash and the badge of becoming the DVD recordable standard.

In the marketplace almost from day one was DVD-R, a format championed almost exclusively by Pioneer, that allows you to record once ? and once only - onto a DVD. At the time of writing, Pioneer's DVD-R drive weighed in at an enormous £3500, with blank 3.95Gb DVD-R discs costing £50 each.

Also around from the early days was DVD-RAM, which uses rewriteable discs on drives costing about £400. A rewriteable disc will let you copy information onto it again and again, rather like a floppy disk. Single-sided DVD-RAM discs hold 2.6Gb and cost £20 each, while double-sided blanks offer 5.2Gb and cost £30. A brand new enhancement to the DVD-RAM format will let it store 4.7Gb per side.

But there are compatibility issues. While DVD-R discs will play in almost any drive, DVD-RAM discs will only play back on a DVD-RAM drive or the very latest DVD-Rom drives; even today's newest CDRom and DVD-Rom drives are unlikely to play the new 4.7Gb discs, however.

To further confuse matters, there are two more DVD recordable formats on the way, both offering 4.7Gb per side. These are called DVD-RW and DVD+RW, but neither are available as yet.

The write-once DVD-R format is likely to disappear, leaving the three rewriteable formats to battle it out. DVD-RAM already has quite a foothold, although the big names behind DVD-RW and DVD+RW are unlikely to back down without a fight. The really big problem is that such constant new development renders many of today's DVD-Rom drives incompatible. The supporters of DVD-RW and DVD+RW claim they offer great backwards compatibility with older DVD drives and home players, but that remains to be seen.