What is the difference between buying automobiles clothes and dvd

These observations on the effects of light are based on preliminary tests conducted at NIST. This film, however, is affected by heat; in fact, it is heat generated from the intense laser beam that writes data in the phase-changing film. Heat buildup in RW or RAM discs caused by direct sunlight will accelerate the degradation rate of the phase-changing film just as it does that of the dye in R discs.

The phase-changing film in RW and RAM discs degrades naturally, and from heat buildup by direct sunlight, at a faster rate than the dye in R discs. The polycarbonate substrate, or the plastic composition, that makes up most of the disc is a polymer material that is vulnerable to moisture. Any prolonged exposure to moisture resulting from a spill, humid air, or immersion allows water to become absorbed into the disc, where it may react with any of the layers. Returning the disc to a dry environment will allow the absorbed moisture or water to dissipate out of the disc over time; however, water or a water-based liquid may leave behind, within the disc, contaminants such as dyes or other dissolved minerals.

If the disc has experienced no permanent damage from absorption of the liquid, it should play normally. In NIST tests, a CD totally submerged in clean water for 24 hours was found to be unreadable initially after removal and surface drying.

Contact of the disc with strong organic solvents must be avoided. Harsher solvents such as acetone or benzene will dissolve the polycarbonate and thereby damage the disc beyond repair. Limited contact cleaning with mild solvents such as isopropyl alcohol or methanol is permitted, as these solvents evaporate quickly and will not dissolve the polycarbonate. They may, however, dissolve or damage labels or optional coatings on the label side of the disc.

The effects on optical discs of magnetism, X-rays, microwaves, and radiation can be summarized as follows:. Optical discs should be kept in individual storage containers until used and returned to those containers immediately thereafter. Typical storage containers, as listed below, isolate and help protect discs from airborne contaminants and other foreign material. They also help buffer rapid environmental changes that can cause stresses to the disc.

Cases are designed to keep surfaces of the disc from contact with the inside of the case. Only one disc should be placed on the hub or each hub in the case. To remove the disc, one should press down on the hub tab while holding the outer edge of the disc with the fingers and then lift up. Bending the disc while lifting it off the hub tab should be avoided. For long-term disc storage, it may sometimes be prudent to remove the label insert or booklet from inside the case and attach it to the outside, perhaps in a sleeve.

In theory, the paper can attract moisture and produce higher moisture content in the case. The paper may also spread moisture by contact with the disc. This recommendation is based on no specific tests of the effects of paper inside a case; it is merely a consideration—one that takes on added significance with large amounts of paper inside a disc case and higher-than-recommended humidity conditions.

Anything on an optical disc surface that impedes the ability of the laser to focus on the data layer can result in missing data as the disc is being read. Fingerprints, smudges, scratches, dirt, dust, solvents, moisture, and any other foreign material can interfere with the ability of the laser to read the data. They can also interfere with the ability of the laser to follow the data track in the disc. Light scratches and fingerprints are very common, and while they both can impede laser reading, their effects on the disc are somewhat different.

Scratches affect discs differently depending on the side of the disc affected, the severity and direction of the scratch, and the type of disc. Scratches generally cross data lines or tracks on the disc, and how bad deep and wide they are will determine the extent of interference with laser focus on the data.

Small or occasional scratches will likely have little or no effect on the ability of the laser to read the disc, because the data are far enough below the surface of the disc that the laser is focused beyond the scratch.

Even assuming a scratch is deep or wide enough to influence laser focus, error detection and correction coding in the disc drive can in many cases recover the misread data. However, scratches that are deep, wide, or bunched together can adversely affect the readability of the disc. These scratches can cause the laser to misread enough data to make error correction coding ineffectual.

While data errors generated from scratches that run outward from the center of the disc stand a good chance of correction by the error correction firmware, scratches running in the direction of the track, the same direction as the laser reads the disc, are more likely to cause uncorrectable errors. If scratches are deep enough to damage the data or metal layers on the reading side of a disc, the data cannot be read or repaired.

Scratches on the label side of CDs can be a more serious problem. Because the reflective metal layer and data layer are so close to the surface of the label side of the disc, they can be damaged very easily. A slight indentation, or pinhole in the metal from a scratch, pen, pencil, ultrafine marker, or other sharp object will destroy the reflectivity of the metal in that area on the other side laser reading side and the readability of the data by the laser. This type of damage cannot be repaired.

As with scratches on the laser-reading side, optical disc drives are usually able to read through minor damage easily, even if the damage is caused from the label side. The difference is that this damage is permanent. If the error detection and correction firmware in the disc drive cannot correct the data, it will not be recoverable.

Scratches that do not reach through the thin protective lacquer coating should have no immediate effect but may ultimately expose the metal to moisture, air pollutants, or other adverse environmental influences.

Adhesive labels see page 23 , though also somewhat vulnerable to adverse environmental influences, can provide CDs with extra protection from scratches. The extra layer on printable discs likewise offers protection. Scratches on the label side of single-sided DVDs are not likely to pose a problem.

Its location makes this layer almost impervious to surface scratches; it is in fact unlikely to be affected by any but the deepest scratches-those deep enough to reach the center of the disc where the metal and data lie. Fingerprints, smudges, dirt, or dust on the laser reading side of the disc can disrupt laser focus on the data even more than a scratch can. Dirt or dust on the disc will block or reduce the light intensity of the laser. If severe enough, it will cause the disc drive to miss data as the disc is being read.

Fingerprints, smudges, or dirt cover wide areas of data and will cause the laser beam to go out of focus or lose intensity. They will also cause widespread misreading of data along the data lines or tracks, to an extent that exceeds the error correction capability of the disc drive. Dust can also spin off into the disc drive and collect on the laser head or other internal components. Very good: The book does not look new and has been read but is in excellent condition. There is no obvious damage to the cover the dust jacket if applicable is included for hard covers.

Good: The book has been read but is in good condition. It has very minimal damage to the cover, including scuff marks, but no holes or tears. The dust jacket for hard covers may not be included. The binding has minimal wear. The majority of pages are undamaged with minimal creasing or tearing, minimal pencil underlining of text, no highlighting of text, and no writing in the margins.

There are no missing pages. Acceptable: The book has obvious wear. It may have some damage to the cover, but its integrity is intact. The binding may be slightly damaged, but its integrity is still intact. There may be possible writing in the margins and underlining and highlighting of text, but there are no missing pages or anything that would compromise the legibility or understanding of the text.

Packaging should be the same as what is found in a retail store, unless the item is handmade or was packaged by the manufacturer in non-retail packaging, such as an unprinted box or plastic bag. New—open box: The item is in excellent, new condition with no functional defects.

The item may be missing original packaging and may have been used for testing or demo purposes. The item includes accessories found with the original product and may include a warranty.

See the seller's listing for full details and a description. Certified refurbished: The item is in a pristine, like-new condition. It has been professionally inspected, cleaned, and refurbished by the manufacturer or a manufacturer-approved vendor to meet manufacturer specifications.

The item will be in new packaging with original or new accessories. Seller refurbished: The item has been restored to working order by the eBay seller or a third party. This means the item was inspected, cleaned, and repaired to full working order and is in excellent condition. This item may or may not be in original packaging. See seller's listing for full details. The item may have some signs of cosmetic wear, but it is fully operational and functions as intended. This item may be a floor model or store return that has been used.

For parts or not working: The item does not function as intended and is not fully operational. This includes items that are defective in ways that render them difficult to use, items that require service or repair, or items missing essential components. Open box: The item is in excellent, new condition with no wear. The item may be missing the original packaging or protective wrapping, or it may be in the original packaging but not sealed. The item includes original accessories.

The item may be a factory second. Certified - Refurbished: The item is in a pristine, like-new condition. Excellent - Refurbished: The item is in like-new condition, backed by a one year warranty. It has been professionally refurbished, inspected and cleaned to excellent condition by qualified sellers. The item includes original or new accessories and will come in new generic packaging. It's a hit and miss technology, though. When used badly it can make the picture too dark or bright, which blocks all that lovely 4K detail.

Our Blu-ray player reviews take these factors into account, so you can buy one that will make the most of your film collection. But sometimes the fault can lie with the Blu-ray itself. Which should mean higher quality. These processing technologies could feasibly be on Blu-rays and DVDs, too, but often they are saved for the 4K releases.

The back of a Blu-ray box will tell you what audio formats and processing is on the disc. But Blu-ray players and 4K Blu-ray players are usually backwards compatible with the lower-resolution discs. It's not always the case that a player will be able to play lower-resolution discs, so it's worth checking our Blu-ray player reviews or the store listing before you buy. Not a DVD player, there's really no point. Very few are still made and we don't test them any more. Ideally, you should buy a 4K Blu-ray player.

Despite some 8K TVs now being released, 4K will be the main resolution used by the TV and film industry for years to come. If you don't have a 4K TV already, then it's likely that you will when you next upgrade, and a 4K Blu-ray player will let you make the most of the display, as well as let you watch your existing Blu-ray and DVD collection if you choose the right model - use our TV reviews to help you.

As 4K Blu-ray players and discs become more common the costs will come down. This happened when Blu-ray was taking over from DVD. Blu-ray discs and players cost a fortune during the transition, but now they cost roughly what DVDs and players did then.