About DVD - VI

How should I clean and care for DVDs?

Since DVDs are read by a laser, they are resistant to fingerprints, dust, smudges, and scratches.
However, surface contaminants and scratches can cause data errors. On a video player, the effect of data errors ranges from minor video artifacts to frame skipping to complete unplayability. So it's a good idea to take care of your discs. In general treat them the same way as you would a CD.

Your player can't be harmed by a scratched or dirty disc unless globs of nasty substances on it actually hit the lens. Still, it's best to keep your discs clean, which will also keep the inside of your player clean. Don't attempt to play a cracked disc, as it could shatter and damage the player. It doesn't hurt to leave the disc in the player, even if it's paused and still spinning, but leaving it running unattended for days on end might not be a good idea.
In general, there's no need to clean the lens on your player, since the air moved by the rotating disc keeps it clean. However, if you use a lens cleaning disc in your CD player, you may want to do the same with your DVD player. It's advisable to use a cleaning disc specifically designed for DVD players, because there are minor differences in lens positioning between DVD and CD players.

Periodic alignment of the pickup head is not necessary. Sometimes the laser can drift out of alignment, especially after rough handling of the player, but this is not a regular maintenance item.
Care and feeding of DVDs

Handle only at the hub or outer edge. Don't touch the shiny surface with your popcorn-greasy fingers.
Store in a protective case when not in use. Don't 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.

Make certain 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), pets, small children, and other destructive forces. The DVD specification recommends that discs be stored at a temperature between -20 to 50 °C (-4 to 122 °F) with less than 15 °C (27 °F) variation per hour, at relative humidity of 5 to 90 percent. Artificial light and indirect sunlight have no effect on replicated DVDs since they are made of polycarbonate, polymer adhesives, and metal (usually aluminum or gold), none of which are significantly affected by exposure to light. Exposure to bright sunlight may affect recordable DVDs, specifically write-once DVDs (DVD-R and DVD+R) that use light-sensitive dyes. Magnetic fields have no effect on DVDs, so it's ok to leave them sitting on your speakers.
Coloring the outside edge of a DVD with a green marker (or any other color) makes no difference in video or audio quality. Data is read based on pit interference at 1/4 of the laser wavelength, a distance of less than 165 nanometers. A bit of dye that on average is more than 3 million times farther away is not going to affect anything.

Cleaning and repairing DVDs

If you notice problems when playing a disc, you may be able to correct them with a simple cleaning.
· Do not use strong cleaners, abrasives, solvents, or acids.
· With a soft, lint-free cloth, wipe gently in only a radial direction (a straight line between the hub and the rim). Since the data is arranged circularly on the disc, the micro scratches you create when cleaning the disc (or the nasty gouge you make with the dirt you didn't see on your cleaning cloth) will cross more error correction blocks and be less likely to cause unrecoverable errors.
· Don't use canned or compressed air, which can be very cold and may thermally stress the disc.
· For stubborn dirt or gummy adhesive, use water, water with mild soap, or isopropyl alcohol. As a last resort, try peanut oil. Let it sit for about a minute before wiping it off.
· There are commercial products that clean discs and provide some protection from dust, fingerprints, and scratches. CD cleaning products work as well as DVD cleaning products.

If you continue to have problems after cleaning the disc, you may need to attempt to repair one or more scratches. Sometimes even hairline scratches can cause errors if they just happen to cover an entire error correction (ECC) block. Examine the disc to find scratches, keeping in mind that the laser reads from the bottom. There are essentially two methods of repairing scratches: 1) fill or coat the scratch with an optical material; 2) polish down the scratch. There are many commercial products that do one or both of these, or you may wish to do it yourself with polishing compounds or toothpaste. The trick is to polish out the scratch without causing new ones. A mess of small polishing scratches may cause more damage than a big scratch. As with cleaning, polish only in the radial direction.

Libraries, rental shops, and other venues that need to clean a lot of discs may wish to invest in a commercial polishing machine that can restore a disc to pristine condition after an amazing amount of abuse. Keep in mind that the data layer on a DVD is only half as deep as on a CD, so a DVD can only be repolished about half as many times.

What's a MiniDVD?

The term "miniDVD" confusingly refers to 8-cm DVDs and to CDs with DVD-Video content on them, more appropriately called cDVDs. 8-cm DVDs are defined in the DVD specification and will play on almost all DVD players and drives, but they don't work in most slot-loading systems, such as in cars. cDVDs play on most DVD PCs, but only on very few DVD players


What are .IFO, .VOB, .AOB, and .VRO files? How can I play them?

The DVD-Video and DVD-Audio specifications define how audio and video data are stored in specialized files. The .IFO files contain menus and other information about the video and audio. The .BUP files are backup copies of the .IFO files. The .VOB files (for DVD-Video) and .AOB files (for DVD-Audio) are MPEG-2 program streams with additional packets containing navigation and search information.

Since a .VOB file is just a specialized MPEG-2 file, most MPEG-2 decoders and software DVD players can play them. You may need to change the extension from .VOB to .MPG. However, any special features such as angles or branching will cause strange effects. The best way to play a .VOB file is to use a DVD player application to play the entire volume (or to open the VIDEO_TS.IFO file), since this will make sure all the DVD-Video features are used properly.
Many DVDs are encrypted, which means the .VOB files won't play when copied to your hard drive.
If you try to copy the .IFO and .VOB files to a recordable DVD it may not play.

.VRO files are created by DVD video recorders using the DVD-VR format. In some cases you can treat the files just like .VOB files, but in many cases they are fragmented and unplayable. Newer version of Cyberlink PowerDVD, InterVideo WinDVD, and Sonic Cineplayer can play them. Otherwise you'll need a utility such as Heuris Extractor or Panasonic DVD-MovieAlbum to copy them to a hard disk in usable format. Alternatively you can use DVD disc creation software such as InterVideo WinDVD Creator, MedioStream neoDVD, or Sonic MyDVD can import from -VR discs and write out standard DVD-Video discs