DVD-RW
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| Optical discs |
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A DVD-RW disc is a rewritable optical disc with equal storage capacity to a DVD-R, typically 4.7 GB (4,700,000,000 bytes). The format was developed by Pioneer in November 1999 and has been approved by the DVD Forum. The smaller Mini DVD-RW holds 1.46 GB, with a diameter of 8 cm.[1]
The primary advantage of DVD-RW over DVD-R is the ability to erase and rewrite to a DVD-RW disc. According to Pioneer, DVD-RW discs may be written to about 1,000 times before needing replacement.[2] DVD-RW discs are commonly used to store data in a volatile format, such as when creating backups or collections of files. They are also used for home DVD video recorders. One benefit to using a rewritable disc is if there are writing errors when recording data, the disc is not ruined and can still store data by erasing the faulty data.
One competing rewritable format is DVD+RW. Hybrid drives that can handle both, often labeled "DVD±RW", are very popular due to the lack of a single standard for recordable DVDs.
The recording layer in DVD-RW and DVD+RW is not an organic dye, but a special phase change metal alloy, often GeSbTe. 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.
Drive specifications
Standard DVD-R/RW compatible drives use a 650 nm red semiconductor laser diode. The average power consumption rating is 250 mW to 4000 mW. Power consumption varies depending on the write speeds and dual layer support. Higher speed drives require more power for increased data throughput, and dual layer disks require more power to penetrate to the second layer of data.
Dual layer
A specification for dual-layer DVD-RW discs with a capacity of 8.5 GB (8,500,000,000 bytes) was approved by the DVD Forum,[3] and JVC announced their development of the first media in the format in 2005.[4]
However, manufacturing support for rewritable dual-layer discs did not materialize due to costs and expected competition from newer and higher-capacity formats like Blu-ray and HD DVD.
Capacity comparison
| Diameter | Disk Type | Data sectors (2,048 B each) |
Capacity | ||
|---|---|---|---|---|---|
| cm | Bytes | MB | GB | ||
| 12 | DVD-R, DVD-RW (SS-SL) | 2,298,496 | 4,707,319,808 | 4489.250 | 4.7 |
| DVD+R, DVD+RW (SS-SL) | 2,295,104 | 4,700,372,992 | 4482.625 | 4.7 | |
| DVD-R DL (SS) | 4,171,712 | 8,543,666,176 | 8147.875 | 8.5 | |
| DVD+R DL (SS) | 4,173,824 | 8,547,991,552 | 8152.000 | 8.5 | |
| DVD-R DS, DVD-RW DS (SL) | 4,596,992 | 9,414,639,616 | 8978.500 | 9.4 | |
| DVD+R DS, DVD+RW DS (SL) | 4,590,208 | 9,400,745,984 | 8965.250 | 9.4 | |
| DVD-R DS (DL) | 8,343,424 | 17,087,332,352 | 16,295.750 | 17.0 | |
| DVD+R DS (DL) | 8,347,648 | 17,095,983,104 | 16,304.000 | 17.0 | |
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References
- ^ "TEAC Corporation DVD/CD-Rewritable Drive Specification DV-W5500S-000 Rev. 0.94 1/24 DVD/CD-Rewritable Drive Product Specification Model : DV-W5500S-000 Drive Specification" (PDF). TEAC Corporation. Retrieved 30 January 2015.
- ^ "Pioneer Announces New, Lower Prices for DVD-R and DVD-RW Media". Pioneer Electronics USA.
- ^ DVD Specifications for Re-recordable Disc for Dual Layer (DVD-RW for DL) Physical Specifications, Version 2.0
- ^ "JVC Develops World's First Single-sided, Dual Layer DVD-RW Disc Technology" (PDF). 2005-04-04. Archived from the original (PDF) on 2014-12-21. Retrieved 2016-03-25.
Victor Company of Japan, Ltd. (JVC) is pleased to announce that it has developed the world's first [as of April 4, 2005] single-sided, dual layer DVD-RW disc technology with a maximum storage capacity of 8.5GB
External links
- ISO/IEC 17342, 80 mm (1,46 Gbytes per side) and 120 mm (4,70 Gbytes per side) DVD re-recordable disk (DVD-RW)
- ISO/IEC 17342:2004 - publicly available standard
- Understanding Recordable & Rewritable DVD by Hugh Bennett
- DVD Forum