In this section, you will find some of the answers to those puzzling questions you have in the back of your mind regarding DVD technology, but have been afraid to ask.

So, don't be shy, delve right in...

Playing CDs
Anyone who is serious about wanting to hear CDs on a DVD player should look for a model with a dual laser drive. This means the player has two separate laser pickups, with one laser optimised for reading CDs. As an added bonus, many players will now accommodate CD-Rs and CD-RWs, and some will even cope with MP3-formatted CDs.

Region hacking your DVD player
If you have a player that is not multi-zone it's quite possible you can do something about it. Players can be opened up and physically "chipped", but this will void any warranty. A safer option is to discover a software hack. (DVD Nut note: if you would like to know if your player can be changed to multi-zone, e-mail me with the make and model of your player, and I will see what I can find for you.)

Disc problems
Don't automatically blame your player. The DVD-Video standard is generally pretty loosely applied, so discs vary wildly in quality and various discs won't play on a range of players for an amazing array of reasons.

What is layering?
A dual-layer disc has two layers of data. The first layer is semitransparent so the laser can focus through it and read the second layer. The advantage of dual-layers is that twice as much can be stored on the disc. Long movies of up to four hours can be stored on these discs at the same data quality rate as shorter movies.

NTSC and PAL
Like VHS, DVD discs are formatted in both NTSC and PAL television standards. The USA uses NTSC and we (New Zealand) use PAL, but luckily, given that a lot of discs here are from the States, all DVD players sold in PAL countries play both. These multi-standard players partially convert NTSC to a 60Hz PAL signal.

Copy protection
Analogue videotape recording of DVDs is prevented with Macrovision 7.0 or a similar circuit in every player. Macrovision adds a Colorstripe signal that shows up as stripes of colour, light to dark fluctuations and other picture degrading nasties. For this reason it's not even a good idea to hook up your DVD player through your VCR to the TV.

In addition, with computer DVD-ROM drives and DVD recorders now freely available, and with the ever present internet ready to beam pirated movies to the masses, studios and hardware manufacturers have been working overtime to introduce all kinds of copy protection measures.

These are aimed at preventing streaming of DVDs over the web, and preventing copies from a disc to a hard drive, from one disc to another or even from one digital device to another digital device. One of these, called Content Scrambling System (CSS), was quickly cracked and the algorithm that generated the keys posted on the internet. It's a safe bet the hackers are now working on the others.

What is DVD-Audio?
A DVD format developed to hold audio data, DVD-Audio is primarily used for high quality music. DVD-Audio offers at least twice the sound quality of a CD, and discs can hold up to seven times as much information. Discs usually offer 5.1 channel surround sound in addition to two-channel stereo, and will often offer other data like liner notes and images.

Various DVD-Audio compatible DVD players are available, in addition to DVD-Audio dedicated machines. DVD-Audio had a bit of a slow start due to a lot of shagging around with copy protection technologies, but it is slowly starting to take off, with more discs being released.

What is SACD?
Super Audio CD is a rival format to DVD-Audio that was developed by Sony and Philips, and uses a digital recording and reproduction process called Direct Stream Digital. Essentially, DSD creates a 1-bit signal that is sampled at the phenomenal rate of 2.8MHz. Sony and Philips claim this process is simpler than PCM recording, and more accurately reproduces the original analogue waveform of music. SACD discs are able to store both 5.1 multi-channel audio tracks and two-channel stereo tracks.

Hybrid SACD discs are also available which have a conventional CD layer so they can be played on ordinary CD players. Of course, with Sony involved there is the potential for plenty of software courtesy of its recording company division.

THX Ultra certification
Lucsfilm THX has a set of proprietary standards that it applies to cinema set-ups to guarantee its exacting standards of image and sound reproduction. Home theatre components which have THX Ultra certification have been approved by Lucasfilm THX as meeting those standards. An Ultra certification often also means a receiver is equipped with Dolby Digital Surround EX.

DVD recorders
DVD recorders are now available. There are three competing formats called DVD-RAM, DVD-RW and DVD+RW. The formats are not compatible, but discs recorded on the machines are playable on many existing DVD players. All these machines will record programmes off television, and can be used to record footage from your digital or analogue video camera. In addition, you can edit the content of the discs you record. You cannot copy DVD-Video movie discs, but you can play them. Each format has a record once only type disc and a rewritable disc.

Compatible computer DVD drives are now available for each of the formats, which means you can burn material to a DVD disc much as you would with a CD writer.

DVD-ROM
DVD-ROM is the base format of DVD that holds data. A DVD-ROM drive in a computer will read a DVD-Video formatted disc just as a CD-ROM drive will read an audio CD disc. To make this happen, however, you will need both a video card and a sound card that are up to the job, and the appropriate software.

Of course, DVD-ROM drives also read programme data like games, and DVD-Video discs like Shrek incorporate interactive games that are meant to be played on computer.

DVD-ROM drives are expected to take over from CD-ROM as more software appears on DVD discs and the drives get cheaper.