what are the technical differences between dvd+r and dvd-r media and dvd readers/writers?

Answer 1

DVD-R (pronounced as DVDR) is a DVD recordable format. A DVD-R has more storage capacity than a CD-R, typically 4.7 GB (4.38 GiB) instead of 700 MiB, although the capacity of the original standard was 3.95 GB. Pioneer has also developed an 8.54 GB dual layer version, which appeared on the market in 2005. A DVD-R can be written to only once, whereas a DVD-RW (DVD-rewritable) can be rewritten multiple times.

The DVD-R format was developed by Pioneer in autumn of 1997. It is supported by most DVD players, and is approved by the DVD Forum.

A competing format is DVD+R (also DVD+RW for the rewritables). Hybrid drives that handle both formats are often labeled DVD±R and Super Multi (which includes DVD-RAM support) and are very popular.

The larger storage capacity of a DVD-R compared to a CD-R is achieved through smaller pit size and smaller track pitch of the groove spiral which guides the laser beam. Consequently, more pits can be written on the same physical sized disc. In order to write smaller pits onto the recording dye layer (see CD-R) a red laser beam with a wavelength of 650 nm (for general use recordable DVD) is used in conjunction with a higher numerical aperture lens. Because of this shorter wavelength, DVD-R and DVD+R use different dyes from CD-R to properly absorb this wavelength.

DVD-R discs are composed of two 0.6 mm polycarbonate discs, bonded with an adhesive to each other. One contains the laser guiding groove and is coated with the recording dye and a silver, 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 1.2 mm. 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 1.2 mm of polycarbonate, a DVD's laser beam only has to penetrate 0.6 mm of plastic in order to reach the dye recording layer, which allows the lens to focus the beam to a smaller spot size to write smaller pits.

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 used for motor control etc.

A DVD+R is a writable optical disc with 4.7 GB (4.38 GiB) of storage capacity (actually 2295104 sectors of 2048 bytes each). The format was developed by a coalition of corporations, known as the DVD+RW Alliance, in mid 2002. Since the DVD+R format is a competing format to the DVD-R format, which is developed by the DVD Forum, it has not been approved by the DVD Forum, which claims that the DVD+R format is not an official DVD format.

In October of 2003, it was demonstrated that double layer technology could be used with a DVD+R disc to nearly double the capacity to 8.5 GB per disc. Manufacturers have incorporated this technology into commercial devices since mid-2004 (see DVD+R DL).

Unlike DVD+RW discs, DVD+R discs can only be written to once. Because of this, DVD+R discs are suited to applications such as nonvolatile data storage, audio, or video.

The DVD+R format is divergent from the DVD-R format. Hybrid drives that can handle both, often labeled "DVD±RW", are very popular since there is not yet a single standard for recordable DVDs. There are a number of significant technical differences between the dash and plus formats, although most consumers would not notice the difference. One example is the ADIP system of tracking and speed control being less susceptible to interference and error than the LPP system used by DVD-R, which makes the ADIP system more accurate at higher speeds. Also DVD+R(W) has a more robust error management system than DVD-R(W), allowing for more accurate burning to media independent of the quality of the media. Additional session linking methods are quite a bit more accurate with DVD+R(W) versus DVD-R(W), resulting in fewer coasters (damaged or unusable discs that are practical only to put under cold beverages) due to buffer under-run and multi-session disks with fewer PI/PO errors.

Like other plus media, it is possible to use bitsetting to increase the compatibility of DVD+R media.

As of 2006, the market for recordable DVD technology shows little sign of settling down in favor 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; it has become very difficult to find new devices that can only record to one of the formats.

Answer 2

DVD-R was invented first, and original DVD players could only play DVD-R. DVD+R came along for computer DVD burners, and were cheaper. Today, 99.9% of all DVD players can use either, and as prices for either is now about the same, use whichever you want.

There is a 3rd format, DVD+-RW. A DVD+R or DVD-R can only be burned to once. After that the content of the disk can not be changed, updated, deleted or add to. With a DVD+-RW (think ReWrite), you can continue to add to the disk until it is full, delete files, update files, etc. as if the DVD was a gigantic 4.7 gig floppy disk. The RW DVDs are more expensive. Many people use them when they are putting together a layout for a DVD. They will test it first on a RW, and if it is not perfect, they can correct it. Once they have it perfect, they burn a permanent copy on a -R or +R, and then clear off the RW for reuse on their next project.

The difference between a reader and a writer: A reader can only read existing DVDs, while a writer can also create new DVDs.

Answer 3

I'm going to explain the differences between DVD-R and DVD+R first.

DVD-R

DVD-R allows you to burn data, music, video or anything that you want that is in data form. However, once the DVD-R is full, you cannot delete the data you do not want (even when your DVD-R is not full).

DVD+R

DVD+R is the same thing as DVD-R, but it could be a double layer disk.

DVD+RW

DVD+RW is the same thing as DVD+R, but you can delete previously stored data. (Double Layer

DVD-RW

DVD-RW is a DVD-R that allows you to delete previously stored data.

Here's an excerpt from Wikipedia

DVD History

In the early 1990's two high density optical storage standards were being developed: one was the MultiMedia Compact Disc (MMCD), backed by Philips and Sony, and the other was the Super Density disc (SD), supported by Toshiba, Time-Warner, Matsushita Electric, Hitachi, Mitsubishi Electric, Pioneer, Thomson, and JVC. IBM's president, Lou Gerstner, acting as a matchmaker, led an effort to unite the two camps behind a single standard, anticipating a repeat of the costly format war between VHS and Betamax in the 1980s.

Philips and Sony abandoned their MMCD format and agreed upon Toshiba's SD format (not to be confused with secure digital cards) with two modifications that are both related to the servo tracking technology. The first one was the adoption of a pit geometry that allows "push-pull" tracking, a proprietary Philips/Sony technology. The second modification was the adoption of Philips' EFMPlus. EFMPlus, created by Kees Immink, who also designed EFM, is 6% less efficient than Toshiba's SD code, which resulted in a capacity of 4.7 GB as opposed to SD's original 5 GB. The great advantage of EFMPlus is its great resilience against disc damage such as scratches and fingerprints. The result was the DVD specification Version 1.5, announced in 1995 and finalized in September 1996. In May 1997, the DVD Consortium was replaced by the DVD Forum , which is open to all companies.

"DVD" was originally an initialism for "Digital Video Disc." Some members of the DVD Forum believe that it should stand for "Digital Versatile Disc" to reflect its widespread use for non-video applications. Toshiba, which maintains the official DVD Forum site [1], adheres to the latter interpretation, and indeed this appeared within the copyright warnings on some of the earliest examples. However, the DVD Forum never reached a consensus on the matter, and so today the official name of the format is simply "DVD"; the letters do not officially stand for anything.[2]

The first DVD players and discs were available in November 1996 in Japan, March 1997 in the United States, 1998 in Europe and in 1999 in Australia. The first pressed DVD release was the film Twister in 1996. The film had the first test for 2.1 surround sound. The first titles released in the U.S., on March 19, 1997, by Lumivision, authored by AIX Entertainment, were IMAX adaptations: Africa: The Serengeti, Antarctica: An Adventure of a Different Nature, Tropical Rainforest, and Animation Greats.

By the spring of 1999 the price of a DVD player had dropped below $300 US. At that point Wal-Mart began to offer DVD players for sale, but DVDs represented only a small part of their video inventory; VHS tapes of films made up the remainder. Wal-Mart's competitors followed suit, and DVDs began to increase in popularity with American consumers.

DVD rentals first topped those of VHS during the week of June 15, 2003 (27.7 M rentals DVD vs. 27.3 M rentals VHS). Major U.S. retailers Circuit City and Best Buy stopped selling VHS tapes in 2002 and 2003, respectively. In June 2005, Wal-Mart and several other retailers announced plans to phase out the VHS format entirely, in favor of the more popular DVD format. However, blank VHS tapes are still widely available since DVD video recorders are significantly less common than DVD players. Many films released to theaters from 2004 onwards are released solely to DVD format and not to VHS format. Consumers have predicted that 2006 would be the final year for new releases on VHS.

According to the Digital Entertainment Group (DEG), all DVD sales and rentals (films, television series, special interests, etc) totaled $21.2 billion in 2004. The sales portion of that was $15.5 billion. In comparison, the total 2004 US box office for theatrical rentals was $9.53 billion (per the National Association of Theater Owners or NATO). While the growth of theatrical films on DVD has cooled recently, that of television programs and music video has increased dramatically.

As of 2006, some retailers, such as Circuit City, no longer offer titles on VHS media, instead concentrating solely on DVDs. The price of a DVD player has dropped to below the level of a typical VCR (although DVD recorders are still usually more expensive than VCRs); a low-end player with reasonable quality can be purchased for under $35 US in many retail stores and many modern computers are sold with DVD-ROM drives. Also popular are units that have integrated a DVD and VHS VCR into a single device; these can be purchased for under $100 US. Most, but not all, movie "sets" or series have been released in boxed sets, as have some entire seasons or selected episode volumes of older and newer television programs.

Initially developed for the need of data storage for back-up and transport, DVD recordables are now also used for consumer audio and video recording. Three formats were developed: -R/RW (minus), +R/RW (plus), -RAM (ram).

Dual Layer recording allows DVD-R and DVD+R discs to store significantly more data, up to 8.5 Gigabytes per disc, compared with 4.7 Gigabytes for single-layer discs. DVD-R DL (dual layer — see figure) was developed for the DVD Forum by Pioneer Corporation, DVD+R DL (double layer — see figure) was developed for the DVD+RW Alliance by Sony.

DVD recordable discs supporting this technology are backward compatible with some existing DVD players and DVD-ROM drives. Many current DVD recorders support dual-layer technology, and the price point is comparable to that of single-layer drives, though the blank media remains significantly more expensive. Currently the technology has severe problems with compatibility in hardware DVD players.[citation needed]

The layer change mechanism in some DVD players can show a noticeable pause, as long as two seconds by some accounts. More than a few viewers have worried that their dual layer discs were damaged or defective. An oft-cited example can be found in the film Black Hawk Down, during the scene when a soldier's arm is severed and another soldier picks it up.