4.3 What about recordable DVD: DVD-R, DVD-RAM, DVD-RW, and DVD+RW?
Description
This article is from the DVD Formats FAQ, by jtfrog@usa.net (Jim Taylor) with numerous contributions by others.
4.3 What about recordable DVD: DVD-R, DVD-RAM, DVD-RW, and DVD+RW?
There are five recordable versions of DVD-ROM: DVD-R/authoring,
DVD-R/general, DVD-RAM, DVD-RW, and DVD+RW. All can read DVD-ROM and
DVD-Video discs, but each uses a different type of disc for recording.
DVD-R can record data once (sequentially only), while DVD-RAM, DVD-RW, and
DVD+RW can be rewritten thousands of times. Final versions of the DVD-R and
DVD-RAM version 1.0 specifications were published in August 1997 (see 6.1).
DVD-RW 1.0 and DVD-R 2.0 are being finalized in early 2000. DVD+RW will be
available in early 2001. Most recordable media are not currently usable for
home video recording (see 1.14), though home DVD recorders became available
in Japan at the beginning of 2000. The three erasable formats (DVD-RAM,
DVD-RW, and DVD+RW) are essentially in competition with each other. The
market will determine which of them succeed. DVD-RAM has a head start of
more than a year.
Toshiba, Panasonic, and others released combination DVD-ROM/CD-RW drives
near the end of 1999.
Each writable DVD format is covered briefly below. For more on writable
DVD, see Dana Parker's article at
<http://www.emediapro.net/EM1999/parker1.html>. If you're interested in
writable DVD for data storage, visit Steve Rothman's DVD-DATA page for FAQ
and mailing list info.
DVD-R and DVD-RW
DVD-R uses organic dye polymer technology, like CD-R, and is compatible
with almost all DVD drives and players (the Sony DVP-S7000 and DVP-S3000
being notable exceptions). First-generation capacity was 3.95 billion
bytes, but was later extended to 4.7 billion bytes. Matching the 4.7G
capacity of DVD-ROM was crucial for desktop DVD-ROM and DVD-Video
production. In early 2000, the format was split into an "authoring" version
and a "general" version. The general version will use a 650nm laser
(instead of 635nm) for future ability to write DVD-RAM.
DVD-RW (formerly DVD-R/W and also briefly known as DVD-ER) is a
phase-change erasable format that became available at the end of 1999.
Developed by Pioneer based on DVD-R, using the similar track pitch, mark
length, and rotation control, DVD-RW will be playable in most DVD drives
and players. (Some drives and players are confused by DVD-RW media's lower
reflectivity into thinking it's a dual-layer disc. Simple firmware upgrades
will be required to solve the problem.) DVD-RW uses groove recording with
address info on land areas for synchronization at write time (land data is
unnecessary during reading). Capacity is 4.7 billion bytes. DVD-RW can be
rewritten about 1,000 times. DVD-R discs are expected to last anywhere from
50 to 250 years, about as long as CD-R discs. DVD-RW discs won't last quite
as long. See
<http://www.ee.washington.edu/conselec/CE/kuhn/otherformats/95x9.htm> and
<http://www.cd-info.com/CDIC/Technology/CD-R/Media/Kodak.html> for more
info. For comparison, magnetic media (tapes and disks) lasts 10 to 30
years, high-quality acid neutral paper can last a hundred years or longer,
and archival-quality microfilm is projected to last 300 years or more. Note
that optical media can become technically obsolete within 20 to 30 years,
long before it physically deteriorates.
Pioneer released 3.95G DVD-R 1.0 drives in October 1997 (about 6 months
late) for $17,000. New 4.7G DVD-R 1.9 drives appeared in limited quantities
in May 1999 (about 6 months late) for $5,400. A future version of the drive
will support DVD-R 2.0 media and DVD-RW media. Price for blank DVD-Rs is
about $40. Initial DVD-RW prices will be about the same. Blank media is
being made by Eastman Kodak, Hitachi Maxell, Mitsubishi, Mitsui, Pioneer,
Ricoh, Ritek, TDK, Verbatim, and Victor. Ricoh, Yamaha, Sony, and others
will join Pioneer in making 4.7G DVD-R/RW drives.
In December 1999, Pioneer released DVD-RW home video recorders in Japan.
The unit costs 250,000 yen (about $2,500) and blank discs cost 3,000 yen
(about $30). Since the recorder uses the new DVD-VR (video recording)
format, the discs won't play in existing players (the discs are physically
compatible, but not logically compatible). Recording time varies from 1
hour to 6 hours, depending on quality. The player is expected to be
released in the U.S. and elsewhere around the middle of 2000. Sharp
announced a $2,200 DVD-RW recorder, and Zenith (LG) announced a $2,000
DVD-RW recorder, both expected near the end of 2000.
The advantages of DVD-R and DVD-RW drives, which are used primarily for DVD
production, are higher capacity and compatibility with most DVD players and
drives.
The DVD-R 1.0 format is standardized in ECMA-279.
DVD-RAM
DVD-RAM, with an initial storage capacity of 2.58 billion bytes, uses
phase-change (PD) technology with some MO features mixed in and is not
compatible with current drives (because of defect management, reflectivity
differences, and minor format differences). A wobbled groove is used to
provide clocking data, with marks written in both the groove and the land
between grooves. The grooves and pre-embossed sector headers are molded
into the disc during manufacturing. Single-sided DVD-RAM discs come with or
without cartridges. There are two types of cartridges: type 1 is sealed,
type 2 allows the disc to be removed. Discs can only be written while in
the cartridge. Double-sided DVD-RAM discs are available in sealed
cartridges only. Cartridge dimensions are 124.6mm x 135.5mm x 8.0mm.
DVD-RAM can be rewritten about 100,000 times, and the discs are expected to
last at least 30 years.
DVD-RAM drives appeared in June 1998 (about 6 months late) for $500 to
$800, with blank discs at about $30 for single-sided and $45 for
double-sided. Disc prices were under $20 by August 1998. The first DVD-ROM
drive to read DVD-RAM discs was released by Panasonic in 1999 (SR-8583, 5x
DVD-ROM, 32x CD). Hitachi's GD-5000 drive, released in late 1999, also
reads DVD-RAM discs. Blank DVD-RAM media is manufactured by Hitachi Maxell,
Eastman Kodak, Mitsubishi, Mitsui, Ritek, and TDK.
DVD-RAM version 2.0, with a capacity of 4.7 billion bytes per side, was
published in September (?) 1999. The first drives will appear in early 2000
at about the same price as current DVD-RAMime. 1.0 drives. Future DVD-RAM
discs may use a contrast enhancement layer and a thermal buffer layer to
achieve higher density.
Samsung and C-Cube made a technology demonstration (not a product
announcement) in October 1999 of a DVD-RAM video recorder using the new
DVD-VR format (see DVD-R/RW section above for DVD-VR details). Panasonic
demonstrated a $3,000 DVD-RAM video recorder at CES in January 2000, with
expected availability in late 2000. Samsung said its $2,000 DVD-RAM-based
recorder would be out around the same time. Hitachi showed a camcorder that
uses 8cm DVD-RAM discs, to be available for $3,000 in late 2000.
The DVD-RAM 1.0 format is standardized in ECMA-272 and ECMA-273.
DVD+RW
Phase-Change Rewritable DVD is an erasable format announced by Philips,
Sony, Hewlett-Packard and others based on CD-RW technology. It will become
available in early 2001. DVD+RW is not supported by the DVD Forum (even
though the DVD+RW companies are members), but the Forum has no power to set
standards. DVD+RW drives will read DVD-ROMs and CDs, and probably DVD-Rs
and DVD-RWs, but will not read or write DVD-RAM discs. The drives are
expected to write CD-Rs and CD-RWs. DVD+RW discs, which hold 4.7 billion
bytes (4.4 gigabytes) per side, should be readable in about 70% of the
existing DVD-Video players and DVD-ROM drives.
DVD+RW backers claimed in 1997 that it would be used only for computer
data, not home video, but this was apparently a smokescreen intended to
placate the DVD Forum and competitors. The original 1.0 format, which held
3 billion bytes (2.8 gigabytes) per side and was incompatible with all
existing players and drives, was abandoned in late 1999.
The DVD+RW format uses phase-change technology with a high-frequency
wobbled groove that allows it to eliminate linking sectors. This, plus the
option of no defect management, allows DVD+RW discs to be written in a way
that should be compatible with many existing DVD readers. DVD+RW discs can
be recorded in either CLV format for sequential video access (read at CAV
speeds by drive) or CAV format for random access. DVD+RW media can be
rewritten about 1,000 times (down from 100,000 times in the original
version), and the discs are expected to last at least 30 years.
Media will be produced by MCC/Verbatim. Ricoh and Yamaha have also
announced support for the DVD+RW format.
Philips announced a DVD+RW home video recorder, to be available "after mid
2000." [Jim's prediction: we won't see it until early 2001.] Unlike the
Pioneer DVD-RW recorder, the Philips recorder will use the DVD-Video
format, so discs will play in many existing players.
More DVD+RW information is at <http://www.dvdrw.org>. The obsolete DVD+RW
1.0 format is standardized in ECMA-274.
Others
Other upcoming potential competitors to recordable DVD include AS-MO
(formerly MO7), which holds 5 to 6 billion bytes, and NEC's Multimedia
Video Disc (MVDisc, formerly MMVF, Multimedia Video File), which holds 5.2
billion bytes and is targeted at home recording. ASMO are expected to read
DVD-ROM but not DVD-RAM or first-generation DVD+RW. MVDisc is similar to
DVD-RW and DVD+RW, using two bonded 0.6mm phase-change substrates, land and
groove recording, and a 640nm laser, but contrary to initial reports, the
drives won't be able to read DVD-ROM or compatible discs.
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