DVD-R

DVD-R is a digital optical disc storage format. A DVD-R is a DVD that can be written once and read arbitrarily many times.

A DVD-R typically has a storage capacity of 4.7 GB. Pioneer has also developed an 8.5 GB dual layer version, DVD-R DL, which appeared on the market in 2005.

DVD-R(W) is one of three competing industry standard DVD recordable formats; the others are DVD+R(W) and DVD-RAM. A DVD-R can be written only once, in contrast with a rewritable DVD formats such as DVD-RW or DVD+RW which can be rewritten multiple (1000+) times.

History

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

Technical specifications

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, a red laser beam with a wavelength of 640 nm (for general use recordable DVD, versus a wavelength of 780 nm for CD-R) 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.