The DVD video format - a brief guide

DVD - what is it?

DVD, standing for "Digital Video Disc" or "Digital Versatile Disc" is a form of optical storage media. It is the same size as a CD, yet can hold digital video, photos, music and data. DVD's have come down in price so much in recent years, it is highly likely that they will end up replacing cds altogether. In fact, many of the latest Hi-Fi systems allow you to play mp3 files directly from DVD. This allows you to store up to 50 albums worth of music on one DVD.

How good is the quality of DVD video?

DVDs provide a far superior format to that of the video tape. However, dvd-video is coded in the MPEG-2 format which is a "lossy" format. This means that information that is deemed as not required by the compression algorithms is removed. Occasionally, as no algorithm is perfect, this can lead to perceptable flaws.

What video information can DVD's store?

• Between one and a half and eight hours worth of high quality video, depending upon whether the disc is single sided single layered (4.7 GB), single sided double layered (8.4 GB) or employing the latest double sided double layered technology (17 GB).
• It can support widescreen or standard formats (16:9 and 4:3 aspect ratios).
• It can support up to 8 different audio tracks to provide translations of the movie into many languages.
• It supports online menus.
• Playing does not degenerate the quality as it did with video tapes. It is safe and quick to fast forward and rewind the DVD as much as is required.

What is DVD audio?

DVD audio is a different format to DVD video, and therefore will not usually play in a standard DVD player. It contains very high fidelity audio, which is copy protected, although it is arguable whether the human ear can distinguish the superior quality audio from normal cd quality music. This format should not be confused with DVD-music. DVD-music is a standard DVD disc containing music files that will play in a standard DVD player.

What are region codes?

There are six region codes that may be applied to a purchased DVD. The region codes are:

1. The US and Canada
2. Europe, South Africa, Greenland, Egypt and Japan
3. South East Asia
4. South and Central America and Australasia
5. Most of Africa and Asia
6. China

The region code denotes the area of the world where playback was intended to take place. This was to artificially prevent DVD's being distributed in countries where they had not yet been officially released eg the latest films are often released in the US first before appearing in the UK. This would allow the film studios to control the distribution and price of the latest movies on a regional basis. However, in practice the majority of DVD players are "multi-region", meaning that they will play discs from any region, or can be modified to do so.

What does the future hold?

Time never stands still in the world of technology, and new formats are currently being developed that will ultimately replace DVD. These include:

• Maxell's Holographic Versatile Disc (HVD) which will be able to store up to 300 GB of data, support a transfer rate of 160 Mbit/s and is due for release at the end of 2006.
• Sony and Panasonic's "Blu-ray Disc" (BD) which can hold up to 50 GB of data on dual layers.
• Toshiba's HD DVD, the HD standing for "High Density" which can hold up to 30GB of data on dual layers.

Both the Blu-ray and HD-DVD technologies will most likely to be able to store more data in the future than is indicated above, by working on multi layer technology to increase the number of layers per disc. Both of these formats should be backwards compatible with current technology.

Sony has recently banned adult films being used by the Blu Ray production system. This has forced the producers of adult films to use the alternative HD-DVD technology. Currently, more movie studios are moving toward Blu Ray than HD-DVD, but this move by Sony could alter the balance the other way. Interestly, the failure of the Betamax video format (against VHS) may have been because Sony banned adult films being processed by Betamax tape duplicators. Could history be repeating itself?

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