PC Hardware in a Nutshell, 3rd Edition [Electronic resources] نسخه متنی

12.2 DVD Writable and Rewritable

In addition to DVD-ROM, there are three
writable DVD formatsDVD-R(A) for
authoring, DVD-R(G) for general recording, and
DVD+Rand three rewritable DVD
formatsDVD-RW,
DVD-RAM, and DVD+RW. All
DVD writers and rewriters can read DVD-ROM discs, but each records to
its own type of disc, none of which is fully compatible with any
other or with existing standard DVD-ROM drives and players.

Incompatibility between the various standards has hindered the market
acceptance of all of them, a problem that manufacturers have begun to
address by introducing hybrid devices that read and write more than
one format. For example, Pioneer produces a combination DVD-R and
DVD-RW drive that also writes CD-R and CD-RW, and next-generation
DVD-RAM drives will read and write DVD-RAM, DVD-R(W), and CD-R(W). As
time passes, we expect this trend to continue.

The DVD Forum has introduced a DVD Multi logo that certifies compatibility with DVD-R, DVD-RW, and DVD-RAM (although not with DVD+RWthe DVD Forum and the DVD+RW Alliance don't much like each other). A DVD Multi drive or player can play all three formats, and a DVD Multi writer can write all three formats.

The following sections
describe the competing writable/rewritable DVD formats.

12.2.1 DVD-R

DVD-R (Recordable) was the first
recordable DVD standard. DVD-R uses organic dye technology, and is
similar conceptually to CD-R. DVD-R discs can be read by most DVD-ROM
drives and DVD players. DVD-R 1.0 drives shipped in late 1997, cost
$17,000, and stored 3.95 GB on a write-once DVD-R 1.0 disc, which at
the time cost $80 each. TheDVD-R 1.0 standard
is specified by ECMA-279
(http://www.ecma-international.org/publications/standards/ECMA-279.HTM).
DVD-R 1.9 drives shipped in mid-1999, cost $5,000,
stored 4.7 GB on a write-once DVD-R 1.9 disc (which at the time cost
$50 each), and could also write 3.95 GB 1.0 discs. DVD-R 2.0 drives
shipped in late 2000, store 4.7 GB on write-once 2.0 discs (which are
copy-protected), and can also write 1.0 and 1.9 discs. DVD-R branched
into two subformats in early 2000:

DVD-R(A)

(DVD-R
Authoring) drives are for professional use, and use a 635
nm laser which can write DVD-R(A) discs, but not DVD-R(G) discs.
DVD-R(A) drives can read either type of DVD-R disc, as can most DVD
drives and DVD players. DVD-R(A) drives sell for $1,500 to $5,000,
and DVD-R(A) discs cost roughly twice what DVD-R(G) discs cost.

DVD-R(G) (DVD-R General)
drives are for home use, are particularly suited to video recording,
and use a 650 nm laser that can also write DVD-RAM discs, although as
of July 2003 only Panasonic has shipped combination DVD-R(G)/DVD-RAM
drives. DVD-R(G) drives can use double-sided discs and incorporate
CPRM (Content Protection for Removable
Media) copy protection, which means that DVD-R(G) drives
cannot be used legally to duplicate DVD-Video discs.

According to various figures we have seen, DVD-R discs can be read by
roughly 85% of older DVD-ROM drives and DVD players.

12.2.2 DVD-RW

DVD-RW (Rewritable) is a newer Pioneer
technology, based on DVD-R but using phase-change erasable media
similar conceptually to CD-RW. DVD-RW was formerly called DVD-ER and
DVD-R/W before Pioneer settled on the DVD-RW designation. Like DVD-R,
DVD-RW stores 4.7 GB per disc and produces discs readable by many
DVD-ROM drives and players, although the lower reflectivity of DVD-RW
discs fools some DVD-ROM players into thinking
they're reading a dual-layer disc. DVD-RW discs can
be read by about 65% of older DVD-ROM drives and DVD players. Recent
DVD-ROM drives or players that have difficulty with DVD-RW discs can
often be upgraded to support DVD-RW simply by installing updated
firmware.

There are three distinct types of DVD-RW discs, all of which store
4.7 GB and can be rewritten about 1,000 times:

DVD-RW 1.0 discs were used with the first DVD-RW drives shipped in
Japan, are seldom seen outside Japan, and have compatibility problems
with some drives.

DVD-RW 1.1 discs do not support CPRM and so cannot be used for
copying any CPRM-protected original DVDs.

DVD-RW 1.1B discs support CPRM, and can be used to copy
CPRM-protected original DVDs (but only if the producer of the
original DVD has encoded the disc to permit copying, and only then by
adhering to the restrictions enforced by the CPRM encoding on the
original disc). In effect, this means that commercial DVD movies
cannot be copied on a DVD-RW drive other than by using special
softwarethe use or even possession of which is illegal in some
jurisdictionsto bypass the copy protection.

In April 2001, Pioneer began shipping the sub-$1,000 DVR-A03 drive,
which despite its name writes DVD-R(G) discs rather than DVD-R(A)
discs. In addition to DVD-R(G) discs, the DVD-A03 writes DVD-RW,
CD-R, and CD-RW, and by March 2002 had dropped to a street price of
about $500. Apple and Compaq bundled relabeled DVR-A03 drives with
some Mac and Presario models, which greatly contributed to the
popularity of DVD-R. Pioneer soon followed with the DVR-A04 drive and
then the DVD-A05 drive, which doubled write speeds to 4X DVD-R, 2X
DVD-RW.

Using 4X DVD-R discs or 2X DVD-RW discs in an older recorder may destroy both the disc and the recorder unless you update the drive firmware before using the newer discs. This problem arises because older recorders do not recognize the newer high-speed discs. In attempting to determine media type, the drive turns on its laser and keeps it on in an endless loop, destroying the disc and burning out the laser. Updating the drive firmware prevents damage to your disc or drive. Pioneer DVR-A03, DVR-103, DVR-A04, and DVR-104 drives are affected, as well as relabeled OEM drives and some standalone recorders produced by Pioneer. Visit http://www.pioneerelectronics.com/hs/ for more details.

Excluding licensing costs, DVD-R(W) drives and
discs are inherently no more costly to produce than CD-R(W), so it is
possible that the broad-based support garnered by DVD-R(W) will
reduce the price of drives and media dramatically, making DVD-R (and
particularly DVD-RW) a viable competitor with other recordable DVD
standards. As of July 2003, DVD-R(G) disks sold for $0.75 to $4 each,
depending on disc quality and packaging, and DVD-RW discs for $1.25
to $5.50 each.

Pure DVD-R(W) drives remain the almost
exclusive preserve of Pioneer, although repackagers such as QPS sell
DVD-R(W) drives under their own labels and other manufacturers such
as Sony produce hybrid DVD-RW/DVD+RW drives that can write DVD-R and
DVD-RW discs. DVD-R(W) has the advantages of wide distribution, the
best suitability for recording video, and the highest compatibility
with older DVD-ROM drives and players. Against those advantages, it
must be said that DVD-R(W) is the least suitable of the competing
technologies for storing data, and therefore the least-appropriate
choice for a general-purpose PC DVD writer.

12.2.3 DVD-RAM

The DVD-RAM
standard is backed by Hitachi, Matsushita (Panasonic), and Toshiba,
which until late 2001 had the writable DVD market all to themselves.
Although DVD-RW and DVD+RW drives became widely available from
several vendors by late 2001, relative to those writable DVD
standards, DVD-RAM has several advantages for use in computers,
including superior defect management, use of zoned CLV (PCAV) for
faster access, and greater media protection via a cartridge. A
DVD-RAM disc can be rewritten at least 100,000 times. Alas, only a
tiny percentage of older DVD-ROM drives and almost no DVD players can
read DVD-RAM discs.

First-generation (DVD-RAM Book 1.0) DVD-RAM drives began shipping in
mid-1998, and used a mix of phase-change and magneto-optical
technology to record 2.58 billion bytes per side on rewritable media.
These discs are not readable by older DVD players and drives,
although some recent DVD-ROM drives will read them. Second-generation
(DVD-RAM Book 2.1) DVD-RAM drives, which began shipping in late 2000,
read and write both original 2.6/5.2 GB DVD-RAM discs and 4.7/9.4 GB
DVD-RAM discs.

Several DVD-RAM media types are available. Single-sided 2.6 GB discs
are available in Type 1 (sealed) or Type 2 (removable) cartridges.
Single-sided 4.7 GB discs are available in Type 2 cartridges.
Double-sided 5.2 GB and 9.4 GB discs were originally available only
in Type 1 cartridges, but are now available in Type 2 cartridges as
well. In late 2002, noncartridge 4.7 GB and 9.4 GB DVD-RAM discs
became widely available. These bare discs can be reliably written and
rewritten in DVD-RAM drives designed to accept them, but many older
DVD-RAM drives simply refuse to write them.

Although a cartridge is advantageous for computer use, a cartridge
raises two issues. First, because standard DVD players and drives
cannot physically accommodate a cartridge, DVD-RAM discs enclosed in
cartridges cannot be read on these devices. Second, once removed from
their cartridges, DVD-RAM discs may no longer be reliably recorded in
some drives, particularly older models, so removing discs from their
cartridges may effectively turn them into write-once media. Most
older DVD-RAM drives will not write reliably (if at all) to a bare
disc, but recent DVD-RAM drives generally write reliably to a
noncartridge disc or to a disc that has been removed from and then
reinstalled in its cartridge.

DVD-RAM 1.0 (2.6/5.2 GB) standards are specified by ECMA-272
(http://www.ecma-international.org/publications/standards/ECMA-272.HTM)
and ECMA-273 (http://www.ecma-international.org/publications/standards/ECMA-273.HTM,
released in June 1999 and February 1998, respectively. DVD-RAM 2.0
(4.7/9.4 GB) standards are specified by ECMA-330 (http://www.ecma-international.org/publications/standards/ECMA-330.HTM)
and ECMA-331 (http://www.ecma-international.org/publications/standards/ECMA-331.HTM),
both released in December 2001.

Superior defect mapping and other technical considerations make
DVD-RAM the best choice for recording data, but its limited
compatibility with older DVD-ROM drives and players makes it a poor
choice for recording video. If you need a DVD writer solely to back
up or archive computer data, DVD-RAM may be the best choice, although
DVD-RAM discs cost more than DVD-R(W) and DVD+R(W) discs, and the
write speed of DVD-RAM drives is much lower than that of DVD-RW and
DVD+RW drives. If you need to record video to be played back on
standard DVD-ROM drives or players, choose another technology.

12.2.4 DVD+RW

Originally
called DVD+RW, changed to +RW when the DVD Forum objected, and later
changed back, DVD+RW is backed by Hewlett-Packard, Mitsubishi
Chemical, Philips, Ricoh, Sony, Thomson Multimedia, and Yamaha.
Although all are members of the DVD Forum, the DVD+RW standard is not
recognized by that organization. First-generation DVD+RW drives were
to use phase-change rewritable technology to store 2.8 GB per side.
DVD+RW manufacturers formally abandoned the 2.8 GB DVD+RW 1.0
standard in late 1999, without ever having produced drives in
commercial numbers. Second-generation DVD+RW drives, which finally
shipped in volume in late 2001, expand capacity to 4.7 GB per side
and support writing CD-R and CD-RW discs. DVD+RW discs are readable
by most recent DVD players and DVD-ROM drives, although as with
DVD-RW the lower reflectivity of DVD+RW discs causes some devices to
mistake them for dual-layer DVD-ROM discs and therefore refuse to
read them. A firmware update solves that problem in many drives and
players that experience it. Roughly 65% of older DVD-ROM drives and
DVD players can read DVD+RW discs.

DVD+RW backers claim two primary advantages for DVD+RW relative to
DVD-RAM. First, like CDs, DVD+RW discs do not use a cartridge
(although non-cartridge DVD-RAM discs are now available). This
translates into lower costs for drives and media, and allows DVD+RW
discs to physically fit standard drives. It also makes DVD+RW drives
a viable alternative for laptop systems, which cartridge-based
DVD-RAM drives are not. Second, DVD+RW drives use CLV access for
sequential data (such as movies) and CAV access for random data,
which allows higher performance. Balanced against this is the fact
that DVD+RW discs can be rewritten only 1,000 times, versus 100,000
for DVD-RAM.

The obsolete and abandoned +RW standard is specified by ECMA-274
(http://www.ecma-international.org/publications/standards/ECMA-274.HTM).
The current DVD+RW standards are maintained by the DVD+RW Alliance
(http://www.dvdrw.com) and as
ECMA-337 (http://www.ecma-international.org/publications/standards/ECMA-337.HTM).
Another good (albeit unofficial) source for DVD+RW information is
http://www.dvdplusrw.org.

12.2.5 DVD+R

The first DVD+RW
drives could use only rewritable DVD+RW discs. CD-R remains popular
despite the availability of rewritable CD-RW discs, and it was clear
to DVD+RW supporters that a write-once version of DVD+RW would fill
an important niche. The write-once version of DVD+RW, as you might
expect, is called DVD+R. DVD+R provides the equivalent of a 4.7 GB
CD-R disc. Roughly 85% of older DVD-ROM drives and DVD players read
DVD+R discs, which is to say they have about the same level of
compatibility as DVD-R discs.

DVD+R discs began shipping in mid-2002, and a firestorm erupted
almost immediately. Some DVD+RW drive makers had preannounced the
availability of DVD+R discs and had told buyers of first-generation
DVD+RW drives that a simple firmware update would allow the drives to
use DVD+R discs as well. That turned out not to be the case, and
buyers of early DVD+RW drives learned that the only way to add DVD+R
support was to replace their drives. Current DVD+RW drives support
DVD+R and DVD+RW discs interchangeably. Like CD-R and DVD-R before
it, DVD+R discs use organic dye technology, so nothing other than
patent royalties prevents DVD+R (and DVD-R) discs from eventually
falling to prices nearly as low as CD-R discs.

12.2.6 Writable DVD Formats Compared

It's clear that the competition to become the
mass-market writable DVD standard is a three-horse race, but it is
uncertain which will ultimately triumph. In the first edition of this
book, we noted that the market had not yet determined a winner in the
writable DVD format wars and that we hoped a single standard would
prevail by the time the second edition was published. We said the
same thing in the second edition, and now we're
forced to say the same in the third.

Perhaps by the time the fourth edition is published
we'll finally have a single standard. But we
won't hold our breath. The issue is the huge amount
of money at stake. If one standard prevails, DVD writers will become
as commonplace as CD writers are now, and DVD blanks will sell by the
billion. The company or consortium that holds the patents on the
winning standard will rake in huge amounts in licensing fees for
drives and discs. That means the companies involved
aren't going to compromise, and the only hope for
achieving a single standard is that the market will sort things out.

These formats have the strong backing of Pioneer and Apple and the
increasing popularity of home video editing to sustain them. DVD-R
and DVD-RW discs are inexpensive (and getting cheaper every month)
and readily available. Current drives write DVR-R discs at 4X, which
matches DVD+R, and DVD-RW discs at 2X, versus the 4X write speed of
DVD+RW. For the time being, DVD-R/RW discs are cheaper than DVD+R/RW
discs, although we expect that to change as DVR+R/RW drives continue
to gain market share.

DVD-R is an excellent choice for recording video because it offers
very high compatibility with older DVD-ROM drives and DVD players.
DVD-R(G) and DVD-RW are not the best choice for recording data
because the DVD-R(W) format lacks defect mapping support (although
new-generation drives may support Mt. Rainier, which implements
defect mapping in drive hardware). DVD-RW is the least-desirable
rewritable standard because its sequential access method prevents
incremental rewrites.

Because of the high price of drives and discs, DVD-R(A) is and is likely to remain a niche product, of interest primarily to professional video producers.

DVD-RAM has been shipping since 1998, is an official standard of the
DVD Forum, is backed by Hitachi, Panasonic, and Toshiba, and has
distinct advantages for recording data. Despite these advantages,
various industry pundits including John Dvorak have declared DVD-RAM
dead. We suspect that DVD-RAM, like Mark Twain, finds the rumors of
its death to be greatly exaggerated. Without question, DVD-RAM
suffers several disadvantages relative to DVD-RW and DVD+RW. DVD-RAM
discs can be read by relatively few DVD-ROM drives and by almost no
DVD players. DVD-RAM discs cost more than DVD-RW or DVD+RW discs.
Finally, DVD-RAM is slow. Whereas DVD+RW rewrites at 4X and DVD-RW at
2X, DVD-RAM rewrites at just 1X, and that's with
write verification turned off. Turning on write verification slows
DVD-RAM writes to a snail-like 0.5X.

So why would anyone use DVD-RAM? Reliability, pure and simple. When
we write 4.7 GB of data to an optical disc, we want some reasonable
assurance that we will later be able to read every bit of that data
without error. The defect mapping and robust error detection and
correction of the DVD-RAM format provide a level of assurance that
other rewritable formats do not.

DVD+RW and DVD+R are not recognized by the DVD Forum, but are backed
by the DVD+RW Alliance, which comprises, among others, Dell, HP,
Mitsubishi/Verbatim, Philips, Ricoh, Sony, Thomson, and Yamaha.
Second- and third-generation DVD+RW drives write DVD+R discs at 4X
and rewrite DVD+RW discs at 2.4X or 4X. DVD+R discs are compatible
with roughly 85% of older DVD-ROM drives and DVD players, which is
comparable to DVD-R compatibility. DVD+RW discs are compatible with
about 65% of older drives and players, which again is comparable to
DVD-RW compatibility.

Relative to DVD-RAM drives, DVD+RW drives offer much higher speed at
the expense of less-robust error detection and correction. Relative
to DVD-RW drives, DVD+RW drives offer the following advantages:

Current DVD+R and DVD+RW drives write high-speed discs at 4X, versus
DVD-R 4X writes and DVD-RW 2X writes.

Although 2.4X DVD+RW drives were not designed to use 4X discs, many such drives can use 4X discs if you upgrade the firmware.

Although DVD-RAM provides the best error detection and correction,
current DVD+RW drives provide error detection and correction superior
to DVD-RW drives, which do not support hardware defect management.
The defect management used by DVD+RW drives is invisible to standard
DVD-ROM drives and DVD players.

DVD+RW drives support lossless linking, which means they can rewrite
any individual sector of a DVD+RW disc directly, while maintaining
compatibility with DVD-ROM drives and DVD players. Lossless linking
also enables packet writing and Mt. Rainier (EasyWrite) support.
Conversely, making a change to a DVD-RW disc requires rewriting the
entire disc.

DVD-RW and DVD+RW discs must be formatted before they can be written
to. The difference is that DVD-RW drives format discs in the
foreground, which may take an hour to complete in a 1X drive. DVD+RW
drives format discs in the background. After formatting the lead-in
and a portion of the data area, which requires only a minute or so, a
DVD+RW drive can immediately begin writing data to the disc as
formatting continues in the background. A partially formatted disc
can be ejected at any time and can be read by a standard DVD-ROM
drive. When you reinsert the disc in the DVD+RW drive, formatting
recommences and continues until completion.

DVD+RW drives support the DVD+VR video format, which allows editing a
video disc while maintaining compatibility with DVD players.
Conversely, the VR format used by DVD-RW drives requires rewriting
the entire disc if you make even a minor change.

Here's our take on the competition. For backing up
or archiving computer data, the best choice is a DVD-RAM drive. For
general-purpose DVD writing, the best choice is a DVD+R/RW drive or a
hybrid drive that can write DVD-R, DVD-RW, DVD+R, and DVD+RW. Such
drives are often called DVD±RW drives (pronounced
DVD-plus-or-minus-RW), an unofficial but useful designation that
probably annoys both the DVD Forum and the DVD+RW Alliance.
DVD±RW drives can write any DVD blank except DVD-RAM,
which allows you to choose media type by price and suitability for
the intended use. DVD+R and DVD-R blanks are fine for recording
video, and DVD+RW blanks are usable (if not ideal) for backing up and
archiving data.

All these technologies are legally useless for duplicating DVD-Video discs (although very few technical hurdles exist and many people already do it on a regular basis). Laws such as the Digital Millennium Copyright Act (DMCA) and standards such as CPRM have effectively eliminated Fair Use provisions of traditional copyright. You can use these drives to store data or video that you have produced, but not as a digital VCR or to back up your DVD-Video discs, at least without breaking the law . Movie industry lobbyists are fighting desperately to make sure you don't have that option.

12.2.7 Read/Write Compatibility

Table 12-2 lists read/write compatibility between
various types of DVD drives with CD and DVD media. Drives are in the
heading row; media types are in the left column. The first circle
indicates read compatibility and the second write compatibility. An
asterisk on either or both sides of the slash means some but not all
drive models of that type read and/or write the media type in
question, possibly with limitations, which may be drive- or
media-specific. For example, only some recent DVD-ROM drives can read
DVD-RAM media, and some DVD-ROM drives cannot read DVD-RW media
because they mistake them for dual-layer DVD-ROM discs.

Compatibility may vary by drive manufacturer. For example, a DVD-ROM
drive made by a member of the DVD-RAM group may read DVD-RAM discs,
but is unlikely to read DVD+RW discs. Conversely, a DVD-ROM drive
made by a member of the DVD+RW group may read DVD+RW discs, but is
unlikely to read DVD-RAM discs.

12.2.8 Choosing a Writable DVD Drive

You take a risk no matter which of the
three competing technologies you choose. Whichever you buy,
there's a chance it will be orphaned if the market
chooses one of the others. So which of these drives should you buy?

If you need reliable, high-capacity optical storage for data, get a
DVD-RAM drive. A DVD-RAM drive is slower than the alternatives and
won't write CD-R or CD-RW, but has very reliable
error correction. DVD-RAM is suitable if the drive and the data it
stores will be used on one computer, or if you need to transfer large
amounts of data between computers that all have DVD-RAM drives. Other
than performance and higher media cost, the chief drawback of DVD-RAM
is that DVD-RAM discs are incompatible with many DVD-ROM drives and
DVD players. In short, DVD-RAM is the most reliable of the competing
formats for storing large amounts of data, but is the best choice
only if high write speeds are unimportant and you will never need to
read the DVD-RAM discs in a system without a DVD-RAM drive.

If you need a general-purpose DVD writer, get a DVD+R/RW drive or a
hybrid DVD+/-RW drive. These drives can write any DVD blank except a
DVD-RAM disc, and most can write CD-R and CD-RW discs as well.
DVD+/-RW drives offer the best combination of flexibility and
reliability for most users. They produce discs that are readable by
most DVD-ROM drives and DVD players, and write discs as fast or
faster than competing single-standard drives. They are ideal for
writing video discs, and a reasonable choice for backing up and
archiving data.

We consider single-standard DVD-R/RW drives undesirable because they
limit your choice of media. In particular, we recommend against a
DVD-RW drive no matter how low the price unless you are certain you
will never use the drive for anything except recording video to DVD-R
discs. In our opinion, DVD-RW compares poorly to DVD+RW for most
purposes, so it makes little sense to saddle yourself with what
amounts to a dedicated DVD-R video writer.

A single-standard DVD+R/RW drive is a much better choice. It writes
DVD+R discs, which are as useful for video as DVD-R discs, and also
supports the superior DVD+RW rewritable format. Choosing a DVD+R/RW
drive means you can't write DVD-R/RW discs, which
for now cost a bit less than DVD+R/RW discs, but a single-standard
DVD+R/RW drive costs $50 to $150 less than a hybrid drive of equal
quality.

Although it's still too soon to declare a winner in the writable DVD format wars, as of July 2003 we think DVD+R/RW is the leading candidate. DVD-RAM cannot compete as a mainstream writable DVD format, although it remains the safest format for archiving data. The only advantage that DVD-R/RW has relative to DVD+R/RW is somewhat lower media cost, and that disparity is disappearing quickly. We expect that discs for either format will soon sell at comparable prices. If that comes to pass, DVD-R/RW will simply fade away.