History of DVD
Mar 26, · DVD-RW discs allow you to format and rewrite data multiple times (the "RW" stands for "rewrite"). This allows you to keep using a DVD-RW again and again to transfer or save files. Before you "rewrite" on your DVD-RW you may need to erase the data already on the disc. Feb 06, · The DVD players sold in PAL countries can play both two sorts of DVD discs while most NTSC players are not compatible with PAL DVD format. To be specific, the commercially available DVD players and TVs can play the two standard DVDs in PAL counties.
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Sample DVD Cover Template
13+ DVD Cover Templates – Free Sample, Example Format Download While the content of your DVD is certainly important, you must pay close attention to the presentation of the DVD as well. And that means the cover of the DVD. The DVD+R format was developed by a coalition of corporations—now known as the DVD+RW Alliance—in mid (though most of the initial advocacy was from Sony). The DVD Forum initially did not approve of the DVD+R format and claimed that the DVD+R format was not an official DVD format until January 25, Aug 14, · Unique to the HD DVD format is a "twin disc" capability, which allows both HD DVD content and DVD content to be imprinted on the same disc. Twin discs are HD DVD on one side and normal DVD on the.
Both terms describe DVD optical discs that can be written to by a DVD recorder , whereas only 'rewritable' discs are able to erase and rewrite data. Data is written 'burned' to the disc by a laser , rather than the data being 'pressed' onto the disc during manufacture, like a DVD-ROM. Pressing is used in mass production, primarily for the distribution of home video.
During the burning of a single bit, the laser's intensity affects the reflective properties of the burned dye. By varying the laser intensity quickly, high density data is written in precise tracks.
Since written tracks are made of darkened dye, the data side of a recordable DVD has a distinct color. Burned DVDs have a higher failure-to-read rate than pressed DVDs, due to differences in the reflective properties of dye compared to the aluminum substrate of pressed discs. The larger storage capacity of a DVD-R compared to a CD-R is achieved by focusing the laser to a smaller point, creating smaller 'pits' as well as a finer track pitch of the groove spiral which guides the laser beam.
These two changes allow more pits to be written in the same physical disc area, giving higher data density. The smaller focus is possible with a shorter wavelength 'red' laser of nm, compared to CD-R's wavelength of nm. This is used in conjunction with a higher numerical aperture lens.
The dyes used in each case are different as they are optimized for different wavelengths. Thus, "R" format discs are only suited to non-volatile data storage, such as audio or video. Thus, many discs have the RW logo, but are not rewritable. They are also ideal for home DVD video recorders , where it is advantageous to have a rewritable format capable of digital video data speeds, while being removable, small, and relatively inexpensive. Another benefit to using a rewritable disc is if the burning process produces errors or corrupted data, it can simply be written over again to correct the error, or the corrupted data can be erased.
DVD "dash" R. Higher speed variants, although compatible with lower writing speeds, are written to with the lowest error rate at the rated speed, similarly to CD-RW. It was introduced after the "-" format. The wobble frequency has been increased from All constant linear velocity transfer rates read and write of 2. Thus, specification sheets of optical drives list "2. Earlier optical drives also have a 1. It was then abandoned until , when it was heavily revised in particular, the capacity increased from 2.
Nero DiscSpeed allows proprietarily adding such information for later retrieval. Other changes include the removal of a dedicated SCSI erase command in optical drives , which is done by the software instead that overwrites data with null characters.
This means that the standard does not allow reverting the disc to a blank unwritten state after the first write. As of , the market for recordable DVD technology showed little sign of settling down in favour of either the "plus" or "dash" formats, which is mostly the result of the increasing numbers of dual-format devices that can record to both formats, known as DVD Multi Recorders.
By contrast, DVD Video recorders still [ when? There are a number of significant technical differences between the "dash" and the "plus" format, although most users would not notice the difference. In the PCA, which is located close to the inner edge of the disc, a step procedure is carried out to calibrate vary the power of the disc drive's laser before every and during writing, to allow for small differences between discs and drives.
This process is known as a power test. Calibration during writing allows for small changes in quality between different sections of the disc, such as slightly different optical properties, impurities or dye layer thickness in either the plastic or dye. CDs and possibly DVDs may also have two PCAs: one on the inner edge of the disc, for low speed testing, and another on the outer edge for high speed testing.
This is also known as bitsetting. As RAM stands for Random Access Memory, it works more or less like a hard-drive and was designed for corporate back-up use. Currently available in standard 4. DVD Forum backs this format. It uses physical dedicated sector markers visible as rectangles on the read side of the disc instead of the pre-pits or wobbles used in other types of recordable and rewritable media.
Multi-format drives can read and write more than one format; e. DVD recordable media are sold in two standard sizes, a regular 12 cm size for home recording and computer usage, and a small 8 cm size sometimes known as a miniDVD for use in compact camcorders. The following table describes the maximal speed of DVD-R and the relative typical write time for a full disc according to the reviews from cdrinfo.
Many reviews of multiple brand names on varying conditions of hardware and DVD give much lower and wider measurements than the optimal numbers below. The table below largely assumes CAV. Library of Congress, most recordable CD products have a higher probability of greater longevity compared to recordable DVD products.
Media of higher quality tends to last longer. Using surface error scanning , the rate of correctable errors can be measured. Not all optical drive models are able to scan the disc quality. DVD-R discs are composed of two 0. One contains the laser guiding groove and is coated with the recording dye and a silver alloy or gold reflector. The other one for single-sided discs is an ungrooved 'dummy' disc to assure mechanical stability of the sandwich structure, and compatibility with the compact disc standard geometry which requires a total disc thickness of about 1.
The sandwich structure also helps protect the layer containing data from scratches with a thick "dummy" disc, a problem with CDs, which lack that structure.
Double-sided discs have two grooved, recordable disc sides, and require the user to flip the disc to access the other side. Compared to a CD's 1. In a DVD-R, the addressing the determination of location of the laser beam on the disc is done with additional pits and lands called land pre-pits in the areas between the grooves.
The groove on a DVD-R disc has a constant wobble frequency of In , JVC announced an archival DVD recording medium manufactured with quality control and inspection frequencies techniques greater than is traditionally used in media manufacturing, and using specially developed silver alloy as a reflective layer and organic dye with in-house developed additives to secure long-term data retention. The alloy can be switched back and forth between a crystalline phase and an amorphous phase, changing the reflectivity, depending on the power of the laser beam.
Data can thus be written, erased and re-written. From Wikipedia, the free encyclopedia. Recordable optical disk technology. Optical disc Optical disc drive Optical disc authoring Authoring software Recording technologies Recording modes Packet writing Burst cutting area. Optical media types.
History of optical storage media High-definition optical disc format war. This section needs expansion. You can help by adding to it. July This section needs to be updated. Please update this article to reflect recent events or newly available information.
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