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Store in a protective case when not in use. Do not bend the disc when taking it out of the case, and be careful not to scratch the disc when placing it in the case or in the player tray. Ensure that the disc is properly seated in the player tray before you close it. Keep discs away from radiators, heaters,  hot equipment surfaces, direct sunlight (near a window or in a car during hot weather), LIESEL DE VILLIERS pets, small children, and other destructive Deputy Director, Central Organisation  Nothing. forces. The DVD specification recommends And the official answer is? ‘Nothing.’ The that discs be stored at a temperature original acronym came from ‘digital between 20 to 50°C with less than 15°C What is DVD? disc.’ The DVD Forum decreed in 1999 that variation per hour. Artificial light and indirect DVD, as an international standard, is simply sunlight have no effect on replicated DVDs VD is the new generation of optical three letters. After all, how many people ask since they are made of polycarbonate, poly- disc storage technology. DVD is what VHS stands for? mer adhesives, and metal (usually aluminium Dessentially a bigger, faster CD that Care of DVD players or gold), none of which are significantly can hold cinema-like video, better-than-CD affected by exposure to light. Exposure to audio, still photographs, and computer data. Since DVDs are read by a laser, they are bright sunlight may affect recordable DVDs, DVD aims to encompass home entertain- resistant to fingerprints, dust, smudges, and specifically write-once DVDs (DVD-R and ment, computers, and business information scratches. However, surface contaminants DVD+R) that use light-sensitive dyes. Mag- with a single digital format. It has replaced and scratches can cause data errors. On a netic fields have no effect on DVDs, so it is , is well on the way to replacing DVD player, the effect of data errors ranges fine to leave them sitting on your speakers. videotape and video game cartridges, and from minor video artefacts to frame skipping Colouring the outside edge of a DVD could eventually replace audio CD and to complete unplayability. So it is a good with a green marker (or any other colour) CD-ROM. DVD has widespread support idea to take care of your discs. In general makes no difference in video or audio qual- from all major electronics companies, all treat them the same way as you would a ity. Data is read based on pit interference major companies, and CD. at ¼ of the laser wavelength, a distance of all major movie and music studios. With Your player cannot be harmed by a less than 165 nanometers. A bit of dye that this unprecedented support, DVD became scratched or dirty disc unless globs of nasty on average is more than three million times the most successful substances on it actually hit the lens. Still, it farther away is not going to affect anything. product of all time in less than three years is best to keep your discs clean, which will of its introduction. In 2003, six years after also keep the inside of your player clean. Cleaning and repairing DVDs introduction, there were over 250 million Do not attempt to play a cracked disc, as it If you notice problems when playing a disc, DVD playback devices worldwide, counting could shatter and damage the player. It does you may be able to correct them with a DVD players, DVD PCs, and DVD game not hurt to leave the disc in the player, even simple cleaning. consoles. This was more than half the num- if it is paused and still spinning, but leaving it bers of video cassette recorders (VCR), set- running unattended for days on end might  Do not use strong cleaners, abrasives, ting DVD up to become the new standard not be a good idea. solvents or acids. video publishing. In general, there is no need to clean the  With a soft, lint-free cloth, wipe gently lens on your player, since the air moved by in a radial direction only (a straight line What do the letters DVD stand the rotating disc keeps it clean. However, between the hub and the rim). Since if you use a lens cleaning disc in your CD the data is arranged circularly on the for? player, you may want to do the same with disc, the micro scratches you create All of the following have been proposed as your DVD player. It is advisable to use a when cleaning the disc (or the nasty the words behind the letters DVD. cleaning disc specifically designed for DVD gouge you make with the dirt you did  Delayed, very delayed (referring to the players, because there are minor differences not see on your cleaning cloth) will cross many late releases of DVD formats) in lens positioning between DVD and CD more error correction blocks and be  Diversed, very diversified (referring to players. less likely to cause unrecoverable errors. the proliferation of recordable formats Periodic alignment of the pickup head is  Do not use canned or compressed and other spin-offs) not necessary. Sometimes the laser can drift air, which can be very cold and may  Digital venereal disease (referring to out of alignment, especially after rough han- thermally stress the disc. piracy and copying of DVDs) dling of the player, but this is not a regular  For stubborn dirt or gummy adhesive,  Dead, very dead (from naysayers who maintenance item. use water, water with mild soap, or predicted DVD would never take off) isopropyl alcohol. As a last resort, try  Digital video disc (the original meaning Care and feeding of DVDs peanut oil. Let it sit for about a minute proposed by some of DVD's creators) before wiping it off.  Digital versatile disc (the original mean Handle only at the hub or outer edge. Do  There are commercial products that ing proposed by some of DVD's not touch the shiny surface with your pop- clean discs and provide some protection creators) corn-greasy fingers. from dust, fingerprints, and scratches.

Cape Libr., Nov/Dec 2005 52 PRACTICAL

CD cleaning products work as well as cause errors, or even damage a player, is especially good for double-sided discs, DVD cleaning products. especially if they peel off while the disc is which have no space for stickers. If you continue to have problems after spinning. Pressure-sensitive adhesives break The Library Service is still investigating cleaning the disc, you may need to repair down over time, so it is possible for labels to various products for the cleaning of discs one or more scratches. Sometimes even come loose after a few years. Libraries and and the strengthening of the centre part of hairline scratches can cause errors if they DVD rental outlets often want to label discs the disc which is the most vulnerable. The just happen to cover an entire error cor- or attach magnetic strips for security, but it is commercial products are quite expensive rection (ECC) block. Examine the disc to best not to use them at all. If you must, use and will add significantly to the processing find scratches, keeping in mind that the laser a ring-shaped ‘donut’ label that goes around cost, but if it can extend the life of a DVD it reads from the bottom. the centre of the disc. As long as the circular is worthwhile looking into. Any information There are essentially two methods of label doesn’t interfere with the player clamp- and suggestions on the care of DVDs by repairing scratches: fill or coat the scratch ing onto the hub, it should be fine. If you public libraries will be welcomed. DVDs are with an optical substance; polish down have to use a non-circular sticker, place it as here to stay (for the next few years at least!) the scratch. There are many commercial close to the centre as possible to minimise and we will have to find ways to optimise products that do one or both of these, or unbalancing. Placing a second sticker straight their life span. you may wish to do it yourself with polishing across from the centre will also help. Writ- Source compounds or toothpaste. The trick is to ing with a marker in the clear (not reflective) http:// www.dvddemystified.com/dvdfag.html polish out the scratch without causing new area at the hub is better than using a sticker, ones. A mess of small polishing scratches although there is not much room for writing may cause more damage than a big scratch. in. Write only in the area inside a 44mm Assorted titles on DVD As with cleaning, polish only in the radial di- diameter. Writing anywhere else on the disc rection. It is recommended that DVDs with is risky, since the ink could possibly eat away scratches that cannot be polished down be the protective coating and damage the data CHARL SEPTEMBER returned to the Library Service for repairs. layer underneath. Audiovisual Librarian, Cataloguing Section The DVDs will be handled in the same way In most cases a better alternative for as damaged CDs. security is a case that can only be opened he DVD is a relatively new format with special equipment at the register or that will eventually replace the VHS What happens if a disc is checkout counter. Barcodes, stickers, and T format completely. As a result of security strips can be placed on the case this technological development, the Library scratched? without endangering discs (or players). This Service has started to acquire large numbers Scratches may cause minor data errors that are easily corrected. That is, data is stored on DVDs using powerful error correction techniques that can recover from even large Quick reference guide for care and handling scratches with no loss of data. A common misconception is that a scratch will be worse straight line from the centre of the disc on a DVD than on a CD because of higher Do toward the outer edge storage density and because video is heavily − handle discs by the outer edge or the − use CD/DVD-cleaning detergent, compressed. DVD data density is physically centre hole isopropyl alcohol, or methanol to four times that of CD-ROM, so it is true that − use a non-solvent-based felt-tip remove stubborn dirt or material a scratch will affect more data. But DVD permanent marker to mark the label − check the disc surface before recording. error correction is at least ten times better side of the disc than CD-ROM error correction and more − keep dirt or other foreign matter from Do not than makes up for the density increase. It is disc − touch the surface of the disc also important to realise that MPEG-2 and − store discs upright (book style) in − bend the disc Dolby Digital compression are partly based plastic cases specified for CDs and − use adhesive labels on removal or reduction of imperceptible DVDs − store discs horizontally for a long time information, so decompression does not ex- − return discs in their packaging (or (years) pand the data as much as might be assumed. cases) to minimize the effects of − open a recordable optical disc package Major scratches may cause uncorrectable environmental changes if you are not ready to record errors that will produce an I/O error on − leave discs in their packaging (or − expose discs to extreme heat or high a computer or show up as a momentary cases) to minimize the effects of humidity glitch in DVD-video picture. Paradoxically, environmental changes − expose discs to extremely rapid sometimes the smallest scratches can cause − open a recordable disc package only temperature or humidity changes the worst errors (because of the particular when you are ready to record data on − expose recordable discs to prolonged orientation and refraction of the scratch). that disc sunlight or other sources of ultraviolet − store discs in a cool, dry, dark light Labels or magnetic strips on environment in which the air is clean − write or mark in the data area of the − remove dirt, foreign material, disc (the area the laser ‘reads’) DVDs? fingerprints, smudges and liquids by − clean by wiping in a direction going Labels and adhesive strips are dangerous wiping with a clean cotton fabric in a around the disc. because they can unbalance the disc and 

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