Hardware Reference
In-Depth Information
DVD+R DL, also known as DVD-R9, is a dual-layer version of the DVD+R standard that was
introduced in October 2003. DVD+R DL is essentially a dual-layer version of the DVD+R disc, using
the same recording method, laser wavelength, and other specifications. However, DVD+R DL discs
have two recording layers, with the reflective surface of the top layer being semi-transparent to
permit recording on the second layer. Because of the lower reflectivity of the top layer, some DVD-
ROM drives cannot read DVD+R DL media. DVD+RW DL media is typically rated at 8x recording
speeds.
Multiformat Rewritable DVD Drives
The DVD Multi specification from the DVD Forum was developed for drives and players that are
compatible with all DVD Forum standards, including DVD-R/RW, DVD-RAM, DVD-ROM, DVD-
Video, and eventually DVD Audio (DVD+R/RW are not DVD Forum specifications and are not
supported). The original version of DVD Multi was published in February 2001; the current version,
version 1.01, was approved by the DVD Forum and published in December 2001. The first DVD
Multi products for computers reached the market in early 2003.
To provide support for different types of DVD media in a single drive, all rewritable DVD drive
vendors now sell drives compatible with both DVD+R/RW and DVD-R/RW discs. These drives are
commonly known as DVD±R/RW. LG's Super Multi Drive series was the first to also add
compatibility with DVD-RAM, and most current DVD±R/RW drives from other makers are also
compatible with DVD-RAM. Many (but not all) current drives also support DVD-R DL, so you can
now buy a single drive that supports all common formats supported by both the DVD Forum and the
DVD+RW Alliance. Lite-On uses the term Super AllWrite to refer to drives that support all these
media types.
BD
In February 2002, the leading optical storage companies formed the Blu-ray Disc Founders (BDF)
and announced the initial specifications for BD, a high-capacity optical disc format. By May 2002,
BD specification 1.0 was released, and in April 2003, Sony released the BDZ-S77 for the Japanese
market, the first commercially available BD recorder. In January 2006, the Blu-ray Disc Association
also released a 2.0 specification for BD-RE discs. Blu-ray is a fully rewritable format that enables
recording up to 25GB of data or up to 11.5 hours of standard-definition video on a single-sided,
single-layer 12cm diameter disc (which is the same as existing CDs and DVDs) using a 405nm blue-
violet laser. Dual-layer BD-R DL recorders are also available and can record up to 50GB or 23
hours of standard-definition video. The latest BD specifications, BDXL (recordable) and BD-RE XL
(rewritable), can store up to 100GB or 128GB at 2x or 4x speeds.
Although backward compatibility with DVD and CD is not a requirement of the Blu-ray specification,
it is a feature drive manufacturers have included. One of the main applications for higher-capacity
optical storage is recording high-definition TV, which takes an incredible amount of storage. Current
DVD recorders can't store enough data to handle high-definition video. Blu-ray, on the other hand, is
designed to store up to 4.5 hours of high-definition video (or more than 13 hours of standard
broadcast-quality TV) on a single-layer disc, and 9 hours on dual-layer versions. As with DVD, Blu-
ray uses the industry-standard MPEG-2 compression technology.
BD also supports 3D video playback on different types of devices, including HDTV, computers, and
game systems. For example, Sony has released a firmware upgrade for PlayStation 3 consoles that
