HOME Technology 2003
No optical illusions
For every DVD player sold about 30 DVD disks are sold each year, a trend that will see worldwide demand for read only and re-writable discs more than double to 1.5 billion units in 2004 with annual factory shipments possibly heading to 7 billion units by 2008.

Japanese market research firm Fujiware Rothchild claims global sales of DVD drives and recorders will reach 50 million units in 2004, compared with some 30 million units in 2003, that includes 18 - 25 million DVD drives and 6.7 million DVD recorders.

In fact the DVD as a consumer device is already beginning to outpace its lower capacity cousin the CD and has already left the video market for dead with rental outlets devoting more and more space to DVD titles.

It is estimated over 250,000 New Zealand homes have DVD players and that’s not taking into account games consoles or the latest generation of PCs and laptops that come standard with DVD players.

Optical media, compact discs (CDs) and digital versatile discs (DVDs), have rapidly transformed the way we interact with music, data, photo, and video files. Not only do computers come standard with drives that can read both formats, the CD writer is now a normal and affordable option for both PC and Macintosh and laptops.

External drives, once an expensive add-on, are also becoming mainstream enabling users to take not only their data or music with them but the device that reads and write it.

Imation which manufactures a complete range of CD and DVD media and drives, says the main reasons for the popularity of optical media formats are durability and flexibility.

While users have the choice of write-once media (CD-R) for archiving, music recording and distribution, and rewriteable media (CD-RW) for backup and re-recording, DVD media holds 4.7 gigabytes of information, more than seven times the capacity of a standard CD. This makes DVD media ideal for videos, storing large files or backing up hard drives.

However there is some confusion about the new recordable formats seven different approaches, each with different specifications and drive requirements. Not all are intended for computing (see DVD compatibility chart chart).

Although DVD and CD media and drives have the same form factor, that’s where the similarities end. DVD media achieves its capacity by using multiple recording

layers and recording on both sides of the media. The DVD writes in smaller "pits" (microscopic grooves running in spiral around the disc) than CD technology.

Imation says smaller pits means more data per track. DVD tracks are also closer together and track pitch—the distance from the center of one part of the spiral information to the adjacent part of the track is smaller. This requires special lasers for reading and writing— meaning these drives can’t read CD-ROMs, CD-Rs, CD-RWs, or audio CDs.

However DVD-ROM drive makers have solved the problem by putting two lasers in their drives, one for DVDs, the other for CDs.

DVD accesses data faster than CD and uses more robust error correction. As a result, DVD speed is measured differently. CD drive speeds are expressed as multiples of that formats original data transfer rate "x," or 150KB per second. A 32x CD-ROM drive reads data at 32 times 150Kbit/sec or 4Mbit/secs. In other words DVD’s 1x equals 1.38Mbit/sec which is faster than an 8x CD drive.

Another big difference is that DVD recording uses UDF (Universal Data Format) making it possible to store data, video, audio, or a mix of all three within a single physical file structure. This ensures files can be accessed by any drive, computer, or consumer video.

UDF includes the CD-standard ISO 9660 compatibility, but CDs do not comply with UDF.

There’s been debate over how long DVDs will last. Imation says thorough testing has produced longevity claims of 70 - 100 years. Of course that depends on how you handle them and how well they are stored.

Handling and Cleaning

• Handle the disc only by the outer edge to avoid fingerprints and smears
• Never touch the unlabeled shiny side of a disc. Don’t set it down on a hard surface.

• Use a soft, lint-free cloth for cleaning the disc to remove spots, dust, or fingerprints.

• Always wipe from the centre to the outer edges, never wipe in a circular motion.

• Do not use abrasive or solvent cleaners on the disc.


• Do store the disc in a protective case to avoid scratches.

• Do store discs in a cool, dry place, away from direct light.

• Do not leave the disc in direct sunlight or in a hot, humid environment.

• Do not allow moisture to condense on the disc.

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