FEATURE ARTICLE (A0003) : -
DVD
Formats - Get a clear Picture?
(By Mok Heng Ngee,
Computer Times September 18, 2002)
With prices already below
the $1,000 mark, have you considered getting a DVD burner for
your PC? If so, do some research first, because a DVD created
by certain burners may not run on some DVD players.
Distributing your data or amateur home videos
on DVDs seems like a cool idea, especially since home DVD
players are getting common. A single DVD, or digital versatile
disc, can store between 4.7 GB and 17 GB of data, or seven
times more than a 650 MB CD-ROM.
The DVD movies which you buy are encoded in
a format called DVD Video, which can be read by all home DVD
players and PC DVD drives. Some software makers are also starting
to distribute their applications on a single DVD-ROM instead
of multiple CD-ROMs.
While the two read-only DVD formats -- DVD Video
and DVD-ROM -- are mature today, there is a technology war
being fought over the DVD recordable formats.
Shop around for a DVD burner and you will come
across models supporting different recording formats: DVD-RAM,
DVD-R, DVD-RW, DVD+R and DVD+RW. And yes, the plus sign is
not a typo mistake.
Check the facts about compatibility before you settle for
a DVD burner or player.
| DVD
Burners: How they compare: |
| FORMAT |
PURPOSES |
COMMENTS |
| Read-only
Formats |
| DVD Video |
Used to
commercially distribute movies which can be played
on home DVD players |
Capacity
is 17 GB (if two layers on both sides are used),
huge capacity is big advantage over CD-ROM as more
movie details can be stored. |
| DVD-ROM |
Used
to store/ distribute data in the same way CD-ROMs
are used. |
Similar
to DVD Video, but with computer-friendly file formats. |
| Recordable
formats |
| DVD-R and DVD+R |
Used for
storing data or movies. Write-once only; non rewritable |
Two versions
of DVD-R: DVD-R(G) and DVD-R(A). (DVD+R is relatively
new in the market) |
| DVD-RW |
Used for
storing data or movies. Rewritable up to 1,000 times. |
Supports
only CLV* rotation method; constant bit rate; native
Mac support; may be able to read DVD-RAM disc. |
| DVD+RW |
Same as
above |
Defect management;
supports both CLV and CAV** rotation methods; variable
bit rate; will be supported by Mount Rainier file
system in Windows Longhorn. |
| DVD-RAM |
Used as
a virtual hard disk/ shared storage on PCs. Rewritable
up to 100,000 times. |
Features
random read-write access; capacity is 2.6 GB to
4.7 GB per side. |
| * CLV or Constant Linear
Velocity: The disc is read/ write at a constant
speed regardless of which part of the disc is being
accessed. |
| ** CAV or Constant Angular
Velocity: The disc is read/ write at different speeds
depending on which part of the disc is being accessed. |
| |
|
|
|
Two
camps : -
From the names, it is obvious that DVD-R and
DVD+R are write-once formats.
Like their CD-R counterparts, DVD-R/+R discs
can only be recorded upon once.
On the other hand, DVD-RW and DVD+RW are rewritable
formats, which support up to 1,000 rewrites.
The fact is that the DVD-R/-RW and DVD+R/+RW
specifications originated from different camps, and are backed
by equally influential industrial bodies.
With members including Hitachi, Matsushita (Panasonic),
Toshiba and Pioneer, the DVD Forum (http://www.dvdforum.org/)
and the Recordable DVD Council are behind the DVD-R/-RW (and
DVD-RAM) specifications.
Supporting the DVD+R/ +RW standards is the DVD+RW
Alliance (http://www.dvdrw.com/) with leading companies such
as Sony, Ricoh, Hewlett-Packard, Philips, Mitsubishi, Yamaha
and Thomson Multimedia under the flag.
If you get a DVD-R/-RW burner, make sure you
get the corresponding DVD-R or DVD-RW discs only. All five
types of recordable media are easily available in Singapore
from $8 (for a 4.7 GB DVD-R) to $39 (for a 4.7 GB DVD-RAM).
While both standards record to a 4.7 GB disc,
DVD-RW and DVD+RW differ in several aspects. Most DVD-RW burners
provide native Macintosh support and can also read DVD-RAM
discs.
To make matters more complex, the DVD-R format
are sub-categorised into two groups: DVD-R(A), and DVD-R(G)
-- the A and G representing "Authoring" and
"General" respectively. The difference
is significant since a DVD-R(A) burner may not record to a
DVD-R(G) disc and vice-versa.
Virtual
hard disk : -
While you may want to burn your home videos
on a DVD-R/-RW or DVD+R/ +RW disc, the DVD-RAM format, which
is also supported by the DVD Forum, is geared more towards
data storage.
Unlike the other media types, DVD-RAM discs
are usually sold in cartridges and feature real random read-write
access. You can rewrite data to a DVD-RAM disc for up to 100,000
times. On PCs and Macintoshes, a DVD-RAM drive is very much
like a hard drive of a capacity of between 2.6 GB and 9.4
GB.
Compatibility
issues : -
Now comes the tricky part: compatibility. If
you are one of those gizmo-geeks who had purchased your home
DVD player when it first appeared in the shops, the bad news
is that it is unlikely that your player can play movies recorded
on DVD-RW/+RW discs, although most DVD-R/+R discs should work.
On the other hand, the newer DVD players and
DVD-ROM drives should be able to access data and movies stored
on DVD-R/-RW/+R/+RW discs with the exception of DVD-RAM discs.
DVD-RAM discs are really only good for data back-up and storage.
Most DVD+RW burners will also be able to write
to DVD+R discs. Similarly, most DVD-RW burners will be able
to write to DVD-R discs. And almost all DVD-R/-RW/+R/+RW burners
will be able to read from any of the recordable media types
(except DVD-RAM discs). Most of these (except DVD-RAM burners)
should also be able to read from and write to CD-R and CD-RW
discs.
The above rules only act as a rough guideline;
be sure to ask your dealer about compatibility with the various
DVD recording formats.
So, which standard should you invest your dollars
in if you really want a DVD burner now?
For data back-up or shared network storage,
DVD-RAM is fine, if you ignore the compatibility issues.
For recording home videos, check if the target
DVD player supports your chosen format.
Many have likened the rivalry between the two
DVD recordable camps to the Sony Betamax versus VHS showdown
a couple of decades ago, or the competition between the Iomega
Zip disk and the LS-120 SuperDisk.
Nevertheless, in February this year, several
major electronic makers agreed on greater cooperation for
setting standards when the next generation of blue laser DVDs
appear.
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