| A DVD-RW is a rewritable optical disc | | | | handle both, often labeled "DVD±RW", |
| with equal storage capacity to a DVD-R, | | | | are very popular since there is not yet |
| typically 4.7 GB. The format was | | | | a single standard for recordable DVDs. |
| developed by Pioneer in November 1999 | | | | There are a number of significant |
| and has been approved by the DVD Forum. | | | | technical differences between the |
| Unlike DVD-RAM, it is playable in about | | | | "minus" (or often and incorrectly |
| 75% of conventional DVD players. | | | | "dash") format and the "plus" format, |
| The primary advantage of DVD-RW over | | | | though most consumers would not notice |
| DVD-R is the ability to erase and | | | | the difference. One example is the ADIP |
| rewrite to a DVD-RW disc. According to | | | | system of tracking and speed control |
| Pioneer, DVD-RW discs may be written to | | | | being less susceptible to interference |
| about 1,000 times before needing | | | | and error than the LPP system used by |
| replacement, making them comparable with | | | | DVD-R, which makes the ADIP system more |
| the CD-RW standard. DVD-RW discs are | | | | accurate at higher speeds. In addition, |
| commonly used for volatile data, such as | | | | DVD+R(W) has a more robust error |
| backups or collections of files. They | | | | management system than DVD-R(W), |
| are also increasingly used for home DVD | | | | allowing for more accurate burning to |
| video recorders. One benefit to using a | | | | media independent of the quality of the |
| rewritable disc is if there are writing | | | | media. Additional session linking |
| errors when recording data, the disc is | | | | methods are more accurate with DVD+R(W) |
| not ruined and can still store data by | | | | versus DVD-R(W), resulting in fewer |
| erasing the faulty data. | | | | damaged or unusable discs due to buffer |
| One competing rewritable format is | | | | under-run and multi-session disks with |
| DVD+RW. Hybrid drives that can handle | | | | fewer PI/PO errors.[citation needed] |
| both, often labeled "DVD±RW", are very | | | | Like other "plus" media, it is possible |
| popular since there is not yet a single | | | | to use bitsetting to increase the |
| standard for recordable DVDs. | | | | compatibility of DVD+R media. |
| The recording layer in DVD-RW and DVD+RW | | | | As of 2006, the market for recordable |
| is not an organic dye, but a special | | | | DVD technology shows little sign of |
| phase change metal alloy, often GeSbTe. | | | | settling down in favor of either the |
| The alloy can be switched back and forth | | | | "plus" or "minus" formats, which is |
| between a crystalline phase and an | | | | mostly the result of the increasing |
| amorphous phase, changing the | | | | numbers of dual-format devices that can |
| reflectivity, depending on the power of | | | | record to both formats; it has become |
| the laser beam. Data can thus be | | | | very difficult to find new devices that |
| written, erased and re-written. | | | | can only record to one of the formats. |
| A DVD+R is a once-writable optical disc | | | | However, because the DVD-R format has |
| with 4.7 GB (4.38 GiB) of storage | | | | been in use since 1997, it has had a |
| capacity (more precisely, 2295104 | | | | five-year lead on DVD+R. As such, older |
| sectors of 2048 bytes each). The format | | | | or cheaper DVD players (up to 2004 |
| was developed by a coalition of | | | | vintage) are more likely to favour the |
| corporations, known as the DVD+RW | | | | DVD-R standard exclusively, and when |
| Alliance, in mid 2002. Since the DVD+R | | | | creating DVDs for distribution (where |
| format is a competing format to the | | | | the playing unit is unknown or older) |
| DVD-R format, which is developed by the | | | | the DVD-R format would normally be |
| DVD Forum, it has not been approved by | | | | preferable. |
| the DVD Forum, which claims that the | | | | DVD+R DL (DL stands for Double Layer), |
| DVD+R format is not an official DVD | | | | also called DVD+R9, is a derivative of |
| format. | | | | the DVD+R format created by the DVD+RW |
| In October of 2003, it was demonstrated | | | | Alliance. Its use was first demonstrated |
| that double layer technology could be | | | | in October 2003. DVD+R DL discs employ |
| used with a DVD+R disc to nearly double | | | | two recordable dye layers, each capable |
| the capacity to 8.5 GB per disc. | | | | of storing nearly the 4.7 GB capacity of |
| Manufacturers have incorporated this | | | | a single-layer disc, almost doubling the |
| technology into commercial devices since | | | | total disc capacity to 8.55 GB. Discs |
| mid-2004 (see DVD+R DL). | | | | can be read in many DVD devices (older |
| Unlike DVD+RW discs, DVD+R discs can | | | | units are less compatible) and can only |
| only be written to once. Because of | | | | be created using DVD+R DL and Super |
| this, DVD+R discs are suited to | | | | Multi drives. DL drives started |
| applications such as nonvolatile data | | | | appearing on the market during mid 2004, |
| storage, audio, or video. This can be | | | | at prices comparable to those of |
| very confusing because the DVD+RW | | | | existing single-layer drives. However, |
| Alliance logo is a stylized "RW" (See | | | | the price of DL media ($1 to $5 USD per |
| image, below). Thus, a DVD+R disc can | | | | disc) is many times that of single-layer |
| have the RW logo, but it is not | | | | media. The latest DL drives write double |
| rewritable. | | | | layer discs slower (2.4x to 8x) than |
| The DVD+R format is divergent from the | | | | current single-layer media (8x-16x). |
| DVD-R format. Hybrid drives that can | | | | |