 If
you're like me, you've probably experienced some amount of confusion
regarding DVD media formats. When we talk of DVD technology, we
usually just refer to it as "DVD" period, as if it's just
one type of media. Like CD media, where I've since grown comfortable
with the R (recordable) and RW (re-writable) appendages, I naturally
assumed the same thing about DVD media... Well, I have an appendage
for that assumption: RW, as in Really Wrong. The more I looked around,
the more I discovered I didn't know Jack about DVD media. So I did
some research and discovered there are actually several categories
(and sub-categories) of DVD media.
Outwardly, all DVD media are identical — shiny, round pieces
of plastic 120mm in diameter and 1.2mm thick (just like CD media).
Underneath that shiny plastic, however, are several differences.
Let's take a look at them...
DVD-R
Referred to as DVD "dash" R, this is one of the more common
formats of DVD media. The R, of course, stands for Recordable. DVD-R
is a write-once format, meaning you can't record to the same disc
more than once. There are two sub-categories of DVD-R: General Use
DVD-R and Authoring DVD-R. The latter was designed to meet the needs
of professional content and software developers to create master
discs that will be mass produced. General Use DVD-R was designed
for the rest of us, and is intended for general business and consumer
use such as data archiving and one-time video recording. When we
refer to DVD-R media, we're really talking about the General Use
category, as this is the kind that is most readily available commercially
(such as from LabelGear.com). DVD-R media deliver 2X write performance,
which is roughly the equivalent of a 18X CD write speed. DVD-R media
is compatible with most DVD players and DVD-ROM drives in computers.
In fact, next to professionally-produced pressed media such as what
you'd rent at BlockBuster or NetFlix, it is probably the most compatible
of all the current DVD formats.
DVD-RW
The "dash" RW means that this is a re-recordable format,
also referred to as "re-writable." DVD-RW media is recorded
sequentially, making it an ideal format for streaming video. You
can write to a DVD-RW disc in multiple sessions as long as the disc
has not been "finalized," but DVD players and drives can
only read DVD-RW discs after they've been finalized. Most newer
players and drives (those produced in the last couple of years anyway)
can read DVD-RW media. The drawback to DVD-RW (like CD-RW) is lower
write speeds. Currently DVD-RW media is limited to 1X (comparable
to an 9X CD write speed). DVD-RW media is available from LabelGear.com.
DVD+RW
Referred to as DVD "plus" RW, it is an alternative re-writable
format that is ideal for real-time video recording and random data
recording due to its faster write speeds (2.4X) and lossless linking
technology, which allows the drive or video recorder to more accurately
start and stop the writing process.
DVD+R
DVD+R has the features of DVD+RW, but in a write-once format. It
has the same write speed of 2.4X. This may not seem like a big jump,
but a 2.4X speed will write a full DVD disc about five minutes faster
than a 2X DVD-R drive. While the +R and +RW formats offer higher
data transfer rates than -R and -RW, their playback and retrieval
rates are the same.
DVD-RAM
DVD-RAM (DVD Random Access Memory) is the original DVD Forum-approved
rewritable format. DVD-RAM features random write/read support, so
data can be written and accessed much like a typical hard drive.
No "finalization" is required meaning that users do not
have to open and close write sessions. Of all the DVD media types,
it's the only one designed to act as random access memory, allowing
it to quickly find and retrieve data anywhere on the disc. The DVD-RAM
format also allows for the most re-writes (100,000 times) compared
to the other re-writable formats (1,000). Its convenience, however,
has one major drawback: DVD-RAM media is the least compatible format
with DVD players and older DVD-ROM drives. It's a popular format
for personal computer use, but I believe its popularity is waning.
Compatibility
The -R and +R formats offer the broadest compatibility among players
and drives. Write-once media is more reflective, and thus more compatible,
especially with older set-top players and DVD-ROM drives. The next
most compatible are -RW and +RW media. DVD-RAM is the least compatible.
Price
Currently the -R and -RW media types are the least expensive. These
formats are available under the SureThing brand and are sold at
our sister site, LabelGear.com. +R and +RW are more expensive. These
formats are not yet available on LabelGear.com, but will be in the
near future. DVD-RAM media are the most expensive.
Speed
Compared to CD write speeds, DVD write speeds are roughly nine times
faster, so a DVD 1X write speed is the equivalent of a CD 9X speed.
At 2X DVD speeds, which is the speed of DVD-R media, you could fill
a full 4.7GB disc in about 30 minutes. At 2.4X speeds (+R and +RW)
it would take about 25 minutes. DVD-RW media only allows for 1X
write speeds, so in theory it would take an hour to write a full
4.7GB disc (but if you were going to write a full disc at once,
you wouldn't want to use -RW media in the first place -R is cheaper
and faster for write-once applications).
If you have any questions or comments about this article, please
drop us a line at editor@surething.com. |
