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DVD formats
Blu-ray, DVD+R, DVD+RW, DVD-RAM, DVD-R, DVD-RW, DVD-ROM; which format is compatible with your system?
BLU-RAY
Developed by Sony, Blu-ray Disc (BD) is a next-generation optical disc format
meant for storage of high-definition video and high-density data. The Blu-ray
standard was jointly developed by a group of consumer electronics and PC
companies called the Blu-ray Disc
Association (BDA). Compared to the HD DVD format, its main competitor,
Blu-ray has more information capacity per layer, 25 instead of 15 gigabytes.
Blu-ray gets its name from the shorter wavelength (405 nm) of a "blue"
(technically blue-violet) laser that allows it to store substantially more
data than a DVD, which has the same physical dimensions but uses a longer
wavelength (650 nm) red laser.
Video: Wayde Robson compares HD DVD with Blue-ray
DVD-
These formats are supported by Panasonic, Toshiba, Apple Computer, Hitachi,
NEC, Pioneer, Samsung and Sharp. These formats are also supported by the
DVD Forum.
DVD-R
A DVD-Recordable or DVD-R is an optical disc with a larger storage capacity
than a CD-R, typically 4.7 GB (4.38 GB) instead of 700 MB, although the
capacity of the original standard was 3.95 GB. Pioneer developed the 8.54
GB dual layer version, launched in 2005. A DVD-R can be written to only
once, whereas a DVD-RW (DVD-rewritable) can be rewritten multiple times.
The DVD-R format was developed by Pioneer in autumn of 1997. It is supported
by most DVD players, and is approved by the DVD Forum.
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, 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. 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, which
is key for writing 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.
DVD-RW
A DVD-RW is a rewritable optical disc with equal storage capacity to a
DVD-R, typically 4.7 GB. The format was developed by Pioneer in November
1999 and has been approved by the DVD Forum. Unlike DVD-RAM, it is playable
in about 75% of conventional DVD players.
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, making them comparable
with the CD-RW standard. DVD-RW discs are commonly used for volatile data,
such as backups or collections of files. They are also increasingly used
for home DVD video recorders.
Unlike DVD-R, the DVD-RW standard has always dictated a capacity of 4.7
GB. One competing rewritable format is DVD+RW. Hybrid drives that can
handle both, often labeled "DVD±RW", are very popular
since there is not yet 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.
DVD+
DVD+R and DVD+RW formats are supported by Philips, Sony, Hewlett-Packard,
Dell, Ricoh, Yamaha and others.
DVD+R
DVD+R is a writable optical disc with 4.7 GB (4.38 GiB) of storage capacity.
The format was developed by a coalition of corporations, known as the
DVD+RW Alliance, in mid 2002. Since the DVD+R format is a competing format
to the DVD-R format, which is developed by the DVD Forum, it has not been
approved by the DVD Forum, which claims that the DVD+R format is not an
official DVD format.
In October of 2003, it was demonstrated that double layer technology could
be used with a DVD+R disc to nearly double the capacity to 8.5 GB per
disc. Manufacturers have incorporated this technology into commercial
devices since mid-2004.
Unlike DVD+RW discs, DVD+R discs can only be written to once. Because
of this, DVD+R discs are suited to applications such as nonvolatile data
storage, audio, or video.
The DVD+R format is divergent from the DVD-R format. Hybrid drives that
can handle both, often labeled "DVD±RW", are very popular
since there is not yet a single standard for recordable DVDs. There are
a number of significant technical differences between the dash and plus
formats, and although most consumers would not notice the difference,
the plus format is considered by some to be better engineered.
Like other plus media, it is possible to use bitsetting to increase the
compatibility of DVD+R media.
DVD+RW
A DVD+RW is a rewritable optical disc with equal storage capacity to a
DVD+R, typically 4.7 GB. The format was developed by a coalition of corporations,
known as the DVD+RW Alliance, in late 1997, although the standard was
abandoned until 2001, when it was heavily revised and the capacity increased
from 2.8 GB to 4.7 GB. Credit for developing the standard is often attributed
unilaterally to Philips, one of the members of the DVD+RW Alliance. Although
DVD+RW has not yet been approved by the DVD Forum, the format is too popular
for manufacturers to ignore, and as such, DVD+RW discs are playable in
3/4 of today's DVD players.
Unlike the DVD-RW format, DVD+RW was made a standard earlier than DVD+R.
One competing rewritable format is DVD-RW. Hybrid drives that can handle
both, often labeled "DVD±RW", are very popular since
there is not yet a single standard for recordable DVDs.
DVD+RW discs can be rewritten about 1,000 times, making them comparable
with the CD-RW standard. DVD+RW discs are commonly used for volatile data,
such as backups or collections of files. However, they are not as widely
used for home DVD video recorders as DVD-RW, primarily because they were
originally designed for storage of data, rather than of video. Of late,
a number of cheaper and "no-name" manufacturers have started
releasing DVD recorders using the DVD+RW format rather than DVD-RW, leaving
the branded manufacturers (except Philips of course) to fly the DVD-RW
flag. For computer use, the DVD-R non-rewritable variant of DVD-RW is
vastly more popular than DVD+R, and mail order or bulk pricing of DVD-R
media is significantly cheaper than DVD+R.
DVD+RW disks support "lossless linking", which allows re-writing
and editing of content without requiring a full erasure of the disc.
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.
Other DVD Formats
If you thought a DVD weas a just a DVD, think again. There are a number
of different formats vying for a piece of the lucarative DVD and home
entertainment market.
DVD±R
Hybrid drives that handle both formats are labeled DVD±R and Super
Multi (which includes DVD-RAM support) and are very popular.
DVD-RAM
A DVD format wherein DVD-RAM discs can be recorded and erased repeatedly
but are only compatible with devices manufactured by the companies that
support the DVD-RAM format. DVD-RAM discs are typically housed in cartridges.
DVD-R, DVD-RW and DVD-RAM are supported by Panasonic, Toshiba, Apple Computer,
Hitachi, NEC, Pioneer, Samsung and Sharp. These formats are also supported
by the DVD Forum.
DVD-R DL
DVD-R DL (Dual Layer) (Also Known as DVD-R9) is a derivative of the DVD-R
format standard. DVD-R DL discs employ two recordable dye layers, each
capable of storing nearly the 4.7 GB of a single-layer disc, almost doubling
the total disc capacity to 8.54 GB. Discs can be read in many DVD devices
(older units are less compatible) and can only be written using DVD±RW
DL burners.
Dual layer technology is supported by a range of manufacturers including
Dell, HP, Verbatim, Philips, Sony, Yamaha and others. As the name suggests,
dual layer technology provides two individual recordable layers on a single-sided
DVD disc. Dual Layer is more commonly called Double Layer in the consumer
market, and can be seen written asor DVD-R DL.
DVD-RA
DVD-RA is used for authoring and then used for mastering DVD video or
data and is not typically available to the general public.
HD-DVD
A high definition format developed by Toshiba. It has a smaller capacity
than Blu-ray, but is similar to existing formats, meaning multi-compatibility
might be easier to achieve. HD-DVD initially received the backing of major
film studios but eventually they supported the Blu-ray format. In February
2008, Toshiba stopped making HD-DVDs.
HD-DVD-1
Taiwanese R&D organisation, Opto-Electronics & Systems Laboratories,
has produced an alternative to HD-DVD and Blu-Ray, called HD-DVD-1. HD-DVD-1
is more closely related to HD-DVD than Blu-ray, with a 17GB capacity.
However, there is another format (tentatively called HD-DVD-2) which has
similarities to Blu-ray.
HVD
Holographic Versatile Disc (HVD) is an advanced optical disc technology
still in the research stage which would greatly increase storage over
Blu-ray and HD DVD optical disc systems These disks have the capacity
to hold up to 3.9 terabytes of information, which is approximately 160
times the capacity of single-layer Blu-ray Discs. The HVD also has a transfer
rate of 1 Gbit/s.
EVD
China's own digital video disc format is called Enhanced Video Disc or
EVD. Format uses blue-laser discs, just like AOD and Blu-Ray do, but the
exact capacity is not known at the moment. The most interesting part of
the disc's specifications is in its video compression method. EVD uses
proprietary video codecs developed by American On2 Technologies, called
VP5 and VP6 that deliver significantly better video quality with lower
bitrate levels than the MPEG-2 used in DVD-Video discs.
FVD
FVD, or Forward Versatile Disc, is an offshoot of DVD developed in Taiwan
jointly by the Advanced Optical Storage Research Alliance (AOSRA) and
the Industrial Technology Research Institute (ITRI) as a more inexpensive
alternative for high-definition content. The disc is similar in structure
to a DVD, in that pit length is the same and a red laser is used to read
it, but the track width has been shortened slightly to allow the disc
to have 5.4GB of storage per layer as opposed to 4.7GB for a standard
DVD. The specification allows for up to three layers for total of 15GB
in storage. WMV9 is used as the video codec allowing for 135 minutes of
720p video on a dual layer disc and 135 minutes of 1080i video on a 3-layer
disc. FVD uses AAES copy protection which is one of the same schemes used
in both HD-DVD and Blu-Ray discs. FVD is not expected to be marketed outside
of Taiwan.
An FVD disc can either be a FVD-1 or FVD-2 disc: FVD-1: The coding format
of the first-generation of FVD adopts 8/16 modulation codes (same as DVD).
FVD-2: The second-generation will use the more efficient 8/15 coding for
increasing the ECC capability (to avoid DVD patents).
This information was sourced from the DVD Forum and britlink
