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Basic Knowledge |
DVD
writers are not all that different from CD writers, so most of the terminology
and knowledge associated with DVD writing should be familiar to anyone who has
done CD writing before.
Recordable DVDs, unlike recordable CDs, have two different main usages. One,
like recordable CDs, if for data storage. The other is for audio and video
storage (in the form of DVD-Video and DVD-Audio).
There are actually three different standards for DVD recordables, DVD-R/RW,
DVD+R/RW and DVD-RAM. All three different formats come in the 4.7 GB (single
sided, single layer : DVD-5) format, although DVD-RAM come in double sided form
factor (DVD-9). DVD-RAM is the only format that requires a cartridge/caddy,
which means that many drives are not able to read this format. More information
about the different DVD recordable standards can be found on the next
page.
DVD devices (including DVD-ROM drives and DVD video players) will playback DVD
recordable discs, although different devices will have different abilities in
terms of reading. The three different formats also makes things more
complicated, since the different standards also have different compatibility
problems (for example, a DVD video player may read one format, but not the
other). Support for DVD re-writable discs are usually rarer than for write-once
discs. More information about compatibility issues can be found on this
page.
Many first generation DVD recorders did not support CD-R/RW writing, or used
smaller 3.9 GB media. New generation drives pretty much all support CD-R/RW
writing (although usually at lower speeds than dedicated CD-R/RW writers).
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Three Standards and a
Caddy |
The biggest single reason why DVD recording has
not taken off as quickly is perhaps what the press bills as the "Format
Wars".
There is big money to be made in terms of licensing of recordable media standards.
This is why several different companies have formed two different groups to
promote their own DVD recordable format.
The compatibility of these formats are discussed further
on in this article.
DVD-R/RW, created by Pioneer, is support by the DVD-Forum industry group.
DVD+R/RW, created by Sony and HP, is the format of choice of the DVD+RW
Alliance industry group. Despite what you may hear from both camps, neither groups
are "official" groups. And to add to the confusion, DVD-RAM, which is
supported by the DVD-Forum, is also being promoted, although it is mainly
intended for data storage and has the least compatibility with DVD-ROM and
DVD-Video. The DVD-Forum does sound the most official, since they were
responsible for mapping out the DVD-ROM and DVD-Video formats, and are also
behind the now familiar DVD logo that you see plastered everywhere these days.
Despite what you may have read, compatibility for DVD-R/RW and DVD+R/RW with
existing DVD devices is quite similar, and nowhere near 100%.
DVD-R/RW :
DVD-R was the first
format to be introduced. At that time, a SCSI DVD-R burner would set you back
well over $10,000. DVD burners these days retail for less than $300. While you
may think that this is a huge price drop, it actually isn't. Professional DVD-R
burners still costs $10,000, mainly because these can be used in the
duplication of DVD movies (hence, a favorite of DVD pirates). The type of DVD-R
burners that are retailing for the lower cost use "General Use"
DVD-Rs, which cannot be used to duplicate DVDs, because they cannot duplicate
CSS encrypted DVDs (and pretty much all commercial DVD movies use CSS
encryption) - although this does not mean you can't still copy a DVD movie to
one :)
DVD-RW is the re-writable
version of DVD-R. DVD-RW can be written only about 1000 times. More precisely,
each sector on the DVD media can be written 1,000 times.
DVD-R media is probably the cheapest on the market right now, mainly because it
was released earlier than DVD+R, and this is the only reason for the price
differences at the moment (there aren't any technological or production reasons
why one format is cheaper or more expensive than the other). DVD-R media
(standard 2x) can be found for $US 1.50, and DVD-RW can be found for $
The maximum writing speed of DVD-R recorders is 4x (5,540 KB/s). DVD-RW are
written to at 2x (2,770 KB/s).
DVD+R/RW :
DVD+R/RW, as mentioned earlier, is the brain child of the DVD+RW Alliance
group. DVD+RW was actually the first released format, with DVD+R coming in
later to compete with DVD-R. Both formats are similar to their DVD- counterparts,
and so the only real difference that separates these formats is the fact that
they are being supported by different industry groups.
DVD+ media costs more than DVD- media at the moment, mainly because it was
released at a later date - current prices (as of January 2003) for DVD+R media
is between $US 2 and 3, while DVD+RW can be found for between $US 3 to 4.
Prices should drop to around the same level as DVD- within this year.
DVD+RW media supports random read and write, allowing Windows drag and drop
type of file copying. It also supports defect management - more about that
later on. DVD+RW media, like DVD-RW, can only be written to about 1000 times.
The maximum writing speed of DVD+R recorders is 2.4x (3324 KB/s). DVD+RW are
also written to at 2.4x. Note that a 4x DVD+R drive will be released in Q1
2003.
DVD-RAM :
DVD-RAM was the very first re-writable format on the market. Unlike DVD-RW and
DVD+RW, DVD-RAM relies on a cartridge/caddy system, which instantly makes them
physically incompatible with many existing DVD devices. DVD-RAM comes in either
single sided variety (4.7 GB) or double sided (9.4 GB).
DVD-RAM media are the most expensive, costing more than $
DVD-RAM media also supports random read and write and defect management.
DVD-RAM media can be over-written about 100,000 times, much better compared to
the 1000 times that DVD-RW and DVD+RW supports.
The Best of Both Worlds :
There is, however, a simple solution to the problem of deciding the format of
your choice - get a DVD recorder that supports all of them. While such a
recorder doesn't actually exist at the moment, there are however DVD recorders
that support more than one standard.
Take Sony's new DRU500A drive - this DVD recorder drive supports the DVD+R/RW
standard (which is understandable, since Sony was one of the companies behind
the creation of this standard), but a little more surprisingly, it also
supports the competing DVD-R/RW.
There is also Panasonic's new
Comparison Table :
The below is a table that compares the attributes of the various DVD recording
formats discussed on this page. Note that we have yet to discuss in detail
performance and compatibility attributes of these standards, and our opinion of
which format is best will not be made until the end of this article.
|
|
Cost Per (4.7GB) Media |
Writing Speed |
# of Re-writes |
Random Read |
Defect Management |
|
DVD-R |
$1.50 (2x) |
4x |
- |
- |
- |
|
DVD-RW |
$2 - 3 |
2x |
1,000 |
No |
No |
|
DVD+R |
$2 - 3 |
2.4x |
- |
- |
- |
|
DVD+RW |
$3 - 4 |
2.4x |
1,000 |
Yes |
Yes |
|
DVD-RAM |
$7 - 8 |
2x |
100,000 |
Yes |
Yes |
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The Fast and the
Format-less |
This section looks at the performance issues of
the three DVD recording standards.
The DVD+ standards (both DVD+R and DVD+RW) used to have faster writing speeds,
and at 2.4x, this amounts to 3,324 KB/s. However, the new Pioneer A05 drive now
adds 4x burning for DVD-R and 2x burning for DVD-RW (2x burning is equivalent
to 18x CD burning). To put it into perspective, 2x writing, or 2,770 KB/s will
mean that for writing to a full 4.7 GB DVD, a 2.4x drive will be some 5 minutes
faster than a 2x drive. Burning a full 4.7 GB DVD will take around 25 minutes
for a 2.4x drive. A 4x drive will burn the full 4.7 GB in about 15 minutes.
Note that a 4x DVD+R drive will be released in Q1 2003.
Raw burning speed is not the only factor when it comes to performance though.
DVD+RW design ensures shorter lead-in and lead-out times - this will mean it
takes shorter to finalise than DVD-RW media. Formatting for DVD-RM or DVD+RW
media can be done on-the-fly, although some older software for DVD-RW may not
support this feature.
CLV and CAV Burning :
There are also two different recording methods, CLV (Constant Linear Velocity)
and CAV (Constant Angular Velocity). CLV is mainly used in streaming video
applications where high transfer speed is required. CAV has better random
access times, and hence better for computer storage/applications.
DVD-R/RW uses CLV, which makes them good for DVD-Video applications. DVD+R/RW
can use both CLV and CAV.
DVD-RAM uses Zoned CLV, which is a combination of CLV and CAV and similar to
how a hard-disk works.
CD Burning :
CD burning speeds for DVD recorders are usually slower than compared to
dedicated CD burners. However, CD burning speeds are already at super fast
speeds (48X!!), and differences in speed can now be measured in terms of
seconds, rather than minutes.
Comparison Table :
|
|
Maximum |
Burning Time (full 4.7 GB) |
Burning Method |
|
DVD-R |
4x |
15 Minutes |
CLV |
|
DVD-RW |
2x |
30 Minutes |
CLV |
|
DVD+R |
2.4x |
25 Minutes |
CLV and CAV |
|
DVD+RW |
2.4x |
25 Minutes |
CLV and CAV |
|
DVD-RAM |
2x |
30 Minutes |
Zoned CLV |
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Stand-alone by me |
Perhaps the biggest issue when choosing a DVD
recorder, specifically, choosing a particular DVD recording standard to use, is
whether the burned disc will be compatible with your existing DVD devices.
Compatibility is not a big issue when it comes to data storage, in that the DVD
recorder drive you used to burn the DVD will always be able to read the burned
disc back. However, if you plan to use the burned DVD in another computer, this
may pose a slight problem. In general, discs burned at 1x will have greater
chance of being compatible than discs burned at higher speeds.
DVD-ROM Compatibility :
The problem is that not all computer DVD-ROM drives will read all the
recordable formats, in particular, DVD-RAM. DVD-R and DVD+R have the best
chance of being read by your DVD-ROM drive. It's hard to say which, out of
DVD-R and DVD+R, is the most compatible with existing DVD-ROM drive. For DVD-R,
you might argue that since it was designed by the same industry group that
designed DVD-ROM (DVD Forum), compatibility may be better. For DVD+R, you might
argue that since it was released later than DVD-R, compatibility issues may
have been solved. Regardless, newer DVD-ROM drives will most likely be more
compatible than older drives, although do not expect 100% compatibility
whichever format you choose. DVD-RAM is the least compatible (since a cartridge
system is used), so unless your DVD-ROM drive specifically says it is
compatible with DVD-RAM, don't expect it to be compatible. For DVD-R and DVD+R,
expect around 60 to 70 % of all DVD-ROM drives to be compatible with them.
Stand-alone DVD Player Compatibility :
The compatibility issue with stand-alone DVD players is similar to that of
DVD-ROM drives, in that no one format is particularly better than any other.
Again, DVD-R and DVD+R will have better compatibility than DVD-RW, DVD+RW or
DVD-RAM. Also expect 60-70% compatibility.
Comparison Table :
|
|
Compatibility |
|
DVD-R |
Very Good |
|
DVD-RW |
Good |
|
DVD+R |
Very Good |
|
DVD+RW |
Good |
|
DVD-RAM |
Poor |
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Conclusion |
It
is hard to come to a conclusive finding.
One thing is clear though - none of the DVD recording formats existing today are
perfect, each with their own advantages and disadvantages. DVD-R/RW are cheaper
and has the fastest burning speed (4x - unmatched for the time being), while
DVD+R/RW employ better technology. It's hard to foresee which format will be
the final DVD recording format (although at this time, you can pretty much rule
out DVD-RAM as a DVD video recording format).
The Format Wars does not look like it will end anytime soon, which can actually
be a good thing. As long as the Format Wars continue, you can be sure that none
of the current DVD recording formats will be abandoned anytime soon, and so no
matter which format you choose, you can be sure that it will be perfectly
usable, probably long after your next computer upgrade. For those that want to
be sure of this, you can purchase DVD recorders that support multiple formats,
such as the Sony DRU500A or the
But with prices dropping quickly, and with DVD burning technology starting to
mature, now is a good time to consider purchasing a DVD recorder.