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Optical disc authoring
Optical disc Optical disc image Recorder hardware Authoring software Recording technologies Recording modes Packet writing
Optical media types
Laserdisc Compact Disc/CD-ROM: CD-R, CD-RW MiniDisc DVD: DVD-R, DVD-R DL, DVD+R, DVD+R DL, DVD-RW, DVD+RW, DVD+RW DL, DVD-RAM Blu-ray Disc: BD-R, BD-RE HD DVD: HD DVD-R: HD DVD-RAM UDO UMD
Standards
Rainbow Books File systems ISO 9660 Joliet Rock Ridge Amiga extensions to Rock Ridge El Torito Apple ISO9660 Extensions Universal Disk Format Mount Rainier

DVD-R is a DVD recordable format. A DVD-R has a larger storage capacity than a CD-R, typically 4.7 GB (or 4.377 GiB) instead of 700 MB, although the capacity of the original standard developed by Pioneer was 3.95 GB (3.68 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.

Contents 1 History 2 Competing formats 3 Technical specifications 4 References 5 See also 6 External links

The DVD-R format was developed by Pioneer in the 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), causing some people to refer to DVD-R as DVD "minus" R unofficially (though, in countries like the UK, this was always said as standard from the beginning, not just in contrast to the plus later-on). Hybrid drives that handle both formats are often labeled DVD±R and Super Multi (which includes DVD-RAM support) and are very popular.

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. However, because the DVD-R format has been in use since 1997, it has had a five-year lead on DVD+R. As such, older or cheaper DVD players (up to 2004 vintage) are more likely to favour the DVD-R standard exclusively, and when creating DVD’s for distribution (where the playing unit is unknown or older) the DVD-R format would normally be preferable.

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 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. The sandwich structure also helps protecting the data containing layer from scratches by a thick "dummy" disk, a problem with CDs that 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 1.2 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.

• Bennett, Hugh. "In DVD's Own Image: DVD-R Technology and Promise." EMedia Professional July 1998: 30+
• Bennett, Hugh. Understanding Recordable & Rewritable DVD. Cupertino: Optical Storage Technology Association, Apr. 2004. [1]

• DVD
• DVD recorder
• DVD-R DL
• MultiLevel Recording
• CD-R
• DVD+R
• DVD-RW
• DVD+RW
• DVD-RAM

• Understanding Recordable & Rewritable DVD by Hugh Bennett
• Pioneer Corporation
• DVD Forum
• Pro DVD+R(W) comparison of DVD+R(W) and DVD-R(W)
• DVD-R Dual Layer First Look
• Care and Handling of CDs and DVDs by Fred R. Byers