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article last updated on
5.14.2003 | printer-friendly
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DVD-Video is the best thing to come along since the digital audio CD
format. It provides a stunningly detailed picture that is virtually free of noise and surround sound audio that rivals that of the best commercial movie
theaters. With the DVD-Video format’s breakthrough in digital video and audio technology, home theater enthusiasts and movie collectors have a format that finally meets their
needs. And with DVD-Video player prices below $80, DVD-Video is now affordable to most everyday
consumers. The DVD-Video format is seeing phenomenal success world wide, with an adoption rate unequalled by previous technology introductions.
Naturally, the next best thing to come along would be DVD recorders.
The ability to record TV programs and home videos onto a DVD disc would allow DVD technology to fully supplant the home video (VHS)
format. But can we throw away our VCRs yet? In this article, we introduce you to the world of recordable DVD
formats. Yes, formats! (As in more than one.) We will discuss each of the three recordable DVD formats in turn,
highlighting the key differences and addressing each format's backwards compatibility with existing DVD-Video players and computer DVD-ROM
drives. So if you are interested in using DVD recorders to time
shift TV programs, to transfer home videos from camcorder video tapes
to more durable recordable DVD discs, to archive and share home videos
on the robust recordable DVD discs, keep reading...
Three Recordable DVD Formats One big factor playing into the phenomenal success of the DVD-Video format is its single unified
format. Some of you may be old enough to remember the launch of the home video format, with the competing Betamax and VHS
formats. With the success of the DVD-Video format, you would think that
the consumer electronics industry learned something about launching a new product with a single
format. No, unfortunately not. To our dismay, there are no less than three DVD recordable
formats! Equally appalling is that each format is not compatible with the other two.
The formats are DVD-R/RW, DVD+R/RW, and
DVD-RAM. If you want to invest in a DVD recorder today, you
will need to know what you’re getting
into. Don't worry, we will help you choose the most appropriate format
as part of this tutorial.
And when you are ready, we will show you what to look for in our DVD Recorder Buying
Guide.
DVD-R/RW Format
 The DVD-R/RW format consists of the write-once DVD-R
(spoken as “DVD dash R”, not “DVD minus R”) and the rewritable DVD-RW
(spoken as “DVD dash RW”)
formats. “DVD-R/RW” is shorthand for “DVD-R and DVD-RW”. Some literature refers to DVD-R and DVD-RW as two separate formats, but we refer to it as one format, with two variants to account for its write-once
and rewritable characteristics.
Write-once means you can only record to the disc once, like CD-R
discs. You can never erase the recording, and you can never record over
an area that has already been recorded. Rewritable means new information can be re-recorded over a previously recorded segment, making the entire disc reusable for repeated recordings (much like a VHS tape). Of course, the previous recorded segment is erased when you re-record over it.
The DVD-R variant of the DVD-R/RW format was the first to be
defined. Making its debut in late 1997, it quickly followed the DVD-Video format’s introduction in the second quarter of
1997. DVD-R is backwards compatible with most existing DVD-Video players and computer DVD-ROM drives,
perhaps partly due to its early definition. Backwards compatibility ensures that the DVD-R disc will be readable by
existing DVD-Video players and computer DVD-ROM
drives. This allows you to record content to a DVD-R disc and playback on any ordinary DVD-Video player or a computer DVD-ROM drive, whether the unit belongs to you,
a family member, or a friend.  DVD-R comes in two flavors: DVD-R for
Authoring
(a.k.a. “DVD-R Authoring”) and DVD-R for General (a.k.a. “DVD-R General”).
DVD-R for Authoring is for the commercial world, where its primary application is DVD authoring
(or content
generation). DVD-R for General, as the name implies, is for consumer and home
use. When you buy a DVD-R disc, be sure to buy the DVD-R General format.
DVD-R for Authoring discs will not work, as they are designed for DVD-R Authoring devices which employ slightly shorter 625-nm wavelength
lasers. Early DVD-R discs have two capacities, 3.95 GB or 4.7 GB. Nowadays,
all DVD-R discs are made with 4.7 GB capacity.
Recording works on the principle of a red laser permanently transforming a dye-recording layer on the DVD-R disc, similar to how CD-R recording (or “burning”)
works. This permanent transformation of the media is characteristic of a write-once
format. DVD-R has an expected lifespan of about 100
years. Like the DVD-Video format, the video information is written as a single track, starting from the inner-most portion of the disc and
spiraling out to the outer
edge. (We bet you didn't know that.) Since it achieves a reported better than 90% backwards compatibility with existing DVD-Video players and computer DVD-ROM drives,
DVD-R is ideal for archiving and distributing home
videos. There’s a high likelihood that the DVD-R you make would be viewable on any DVD-Video player and computer DVD-ROM drive, but
there is no 100% guarantee. Obviously 100% compatibility would be
expected by everyday consumers, but it is not possible in today’s world of recordable DVD
formats. This is as good as it gets for now. The rewritable version of DVD-R/RW format is the DVD-RW variant, formally known as “DVD Re-Recordable”.
Introduced in late 1999, DVD-RW supports 1,000 rewrite cycles with a 4.7 GB data
capacity. It uses phase-change technology, allowing video and data to be recorded
incrementally as a series of sequential recording
sessions. The format also allows for a single start-to-finish disc-at-once recording session, when the disc is finalized at the
end. Finalization is a process that essentially
"completes" the recording process and makes the disc readable by
playback-only devices. DVD-RW has a backwards compatibility rate of roughly
65% with existing DVD-Video players and DVD-ROM drives. Its expected
shelf life is at least 30 years. As of May 2003,
a blank DVD-R disc costs about $2 - $4, while a blank DVD-RW disc runs
for $6 - $20. DVD-R is more appropriate for home video distribution and archival purposes, while the rewritable DVD-RW format is better suited for TV program time shifting, when you would want to
re-record over TV programs that you have viewed (just like you would reuse a VHS tape
by record over a previously recorded program).
The DVD-R/RW format was initially championed by Pioneer
Electronics, and is supported by the DVD Forum (the same body of industry representation that
is behind the successful DVD-Video
format). Today, DVD-R/RW is supported by the likes of Pioneer, Sony, Toshiba, Apple Computer, and Compaq Computer.
DVD-RW includes provisions for content protection via the Content Protection for Recordable Media
(CPRM). The current crop of standalone DVD-R/RW recorders available today includes the
Pioneer Elite DVR-7000 ($1,200, as low as
$899.88),
Sharp DV-RW2U ($600),
and the Sony RDR-GX7 ($800, available June 2003). For more information on DVD recorders, check
our DVD Recorder Buying
Guide.
Pioneer Elite DVR-7000
DVD-R/RW recorder ($1,200)
(click on image to enlarge)
DVD-R/RW drives for computers are also
available. Together with a DVD authoring software package, you can transfer the digital video footage from your camcorder
to your computer’s hard drive, edit in a non-linear fashion (i.e., random cut and
paste of video segments), and record the final sequence to a DVD-R or DVD-RW disc for playback on most any DVD-Video player and computer DVD-ROM
drive. You can even create professional looking DVD menus and chapter selection, just like commercial DVD-Video movie
titles. For more information on this, read these frequently asked
questions (FAQs).
DVD+R/RW Format
Like the previous format we discussed, the DVD+R/RW format consists of the
write-once DVD+R (spoken as “DVD plus R”) and the rewritable DVD+RW
(spoken as “DVD plus RW” or “DVD plus ReWritable”)
variants. DVD+RW officially stands for “DVD+ReWritable Video”.
Note the previous format had a
dash (“-”), while this format has a plus (“+”). In comparison with the other formats, the DVD+R/RW format was last to be introduced.
The rewritable DVD+RW variant was introduced in late 2001, before its
write-once variant was even conceived. The write-once DVD+R variant was later
announced by Philips at the 2002 Consumer Electronics Show for introduction in
mid-2002. DVD+R/RW competes directly with the DVD-R/RW format.
Interestingly, DVD+R and DVD+RW formats are not endorsed by the DVD Forum, nevertheless, the following manufacturers have committed to this format: Sony (who also supports the DVD-R/RW format), Yamaha, Thomson, Ricoh, Mitsubishi Chemical, Hewlett-Packard, Dell, and
Microsoft. Together, they call themselves the
DVD+RW Alliance.
Microsoft joined the DVD+RW Alliance late, in May 2003.
So what does the DVD+R/RW format have going for it? Well, technically the DVD+R
variant allows editing to be performed until the disc is
finalized. And finalizing a DVD+R disc takes about one minute, versus about 15 minutes for
a DVD-R disc.
Philips claims that DVD+R/RW is backwards compatible with most existing DVD-Video players and computer DVD-ROM
drives. Realistically, expect about
85% backwards compatibility for DVD+R and about
65% backwards
compatibility for DVD+RW.
 DVD+R holds 4.7 GB for a single-sided disc, or 9.4 GB for a double-sided
disc. Video can be recorded in High Quality (HQ) or standard play (SP) recording mode for up to 500 lines of resolution, or in Long Play (LP) or extended play (EP) recording mode for up to 250 lines of
resolution. The DVD+R/RW formats use “lossless linking” to maximize recording
time. This works by minimizing the large blank spots caused by multiple recording sessions.
Like DVD-R, DVD+R uses a red laser to permanently transform a dye-recording layer on the DVD+R disc for write-once
recording. DVD+R has an expected lifespan of about 30-100 years and each
blank disc costs about $4 as of May 2003.
 DVD+RW uses phase-change technology for multiple re-rewrites,
up to 1,000 cycles. It boasts a defect management feature and short formatting
time. DVD+R/RW writes data from the inside edge spiraling out the outer edge,
just like a DVD-Video disc. The format supports recording in both constant angular velocity
(CAV) (constant rotation speed)
and constant linear velocity (CLV) (constant linear track speed, with disc rotation faster when the track
being written to/read from is closer to the inner hub) modes.
You should always use the CLV mode, since CAV recordings cannot be read by
DVD-Video players and computer DVD-ROM drives. A blank DVD+RW disc costs
about $6 as of May 2003.
The current crop of DVD+R/RW recorders available today includes the
Philips DVDR 985 ($600, as
low as $499.88),
Philips DVDR 75, Philips DVDR 80, Yamaha DVD-R2000, and Sony RDR-GX7
($800, available June 2003). For more information on DVD recorders, check out
our DVD Recorder Buying
Guide. DVD+R/RW drives are available for personal computers, and you can use it to burn your DVD+R or DVD+RW disc when you’re done with your non-linear editing and DVD
authoring. For more details on this, read these FAQs.
Philips DVDR 985 DVD+R/RW
recorder ($600)
(click on image to enlarge)
DVD-RAM Format
 The third recordable DVD format is DVD-RAM (spoken
as “DVD ram”).
It was invented by Matsushita, the parent company of Panasonic and Technics,
and was introduced in summer of 1998. The DVD-RAM format is supported by the DVD
Forum. A DVD-RAM disc looks like any other DVD, and the name DVD-RAM incorporates the letters “DVD”.
But make no mistake, DVD-RAM is in many ways not a real DVD. As the
second part of its name clearly states, it is like random access memory
(RAM). The easiest way to explain the DVD-RAM format is to think of it as a removable hard
disk. DVD-RAM uses phase change dual and magneto-optic technologies for up to 100,000 recording cycles.
A single-sided 12-cm (4.75-inch) DVD-RAM disc
(about $8, as of May 2003) holds 4.7 GB, so a double-sided 12-cm DVD-RAM disc (about
$15, as of May 2003) holds 9.4
GB. DVD-RAM discs also comes in a compact size of 8-cm (3-inch). This smaller version is used in DVD-RAM
camcorders from Hitachi and Panasonic. A double sided 8-cm DVD-RAM disc
(about $30) has a capacity of 2.8 GB, enough for 60 minutes of high resolution
video. The early version of the DVD-RAM format required a disc cartridge (or caddy), while later models may or may not use the cartridge
design. The current design allows the disc to be removed from the cartridge housing. DVD-RAM is expected to have a lifespan of about 30 years. DVD-RAM’s principal advantages are its removable hard disk characteristic and robustness, making it ideal for computer data
storage. Data storage is random and non-linear, meaning data can be stored in non-contiguous blocks, much like
a computer hard
disk. In a video editing application, as you perform cut and insert video editing functions with a DVD-RAM recorder,
the video streams can be dynamically linked in the new order that they’re edited, without having to re-record video streams on the disc in physical sequential
order. This is the random access feature of DVD-RAM. Additionally, DVD-RAM incorporates a defect management feature to ensure that
the video stream is recorded in a non-defective area of the disc, so content loss is minimized. Inherent
in its design, a DVD-RAM disc is incompatible with virtually all DVD players and computer DVD-ROM
drives. Only DVD-Video players made by Panasonic since 2001 are
playback-compatible with DVD-RAM
discs. Such players are designated by Panasonic as “DVD-RAM compatible”.
The backwards incompatibility issue puts the DVD-RAM format at a huge disadvantage when it comes to sharing home videos and other recordings with family and friends. Current stand-alone DVD-RAM recorders include the
Panasonic DMR-E50 ($500, as
low as $450), and Panasonic DMR-HS2 ($1,000) with a 40-GB hard disk for more efficient time shifting
functionality. Few other consumer electronics manufacturers have embraced the DVD-RAM
format. Samsung makes the Samsung DVD-R3000 (list $800). For more information on DVD recorders, check out
our DVD Recorder Buying
Guide. DVD-RAM drives are also available for personal computers. For computer data storage applications, DVD-RAM is a highly attractive format for the reasons we previously
discussed.
Panasonic DMR-E50 DVD-RAM
and DVD-R recorder ($500)
(click on image to enlarge)
Standalone DVD recorder or a computer with recordable DVD drive?
Since you can record DVDs using either a standalone DVD recorder or a computer with a recordable DVD drive, which is the better choice?
The answer depends on what you want to do. Our guess is that most everyday consumers will want to do the following:
-
 transfer,
copy, distribute/share, and archive their home video collection
on recordable DVD media
-
time shift TV programs to view at a more convenient
time, using recordable DVD media
If this is all you want to do then a standalone DVD recorder is the better
choice. However, if you want to:
-
edit home video footage from your camcorder and author a professional-looking DVD,
complete with chapters/scene selections
-
archive video footage downloaded from the web and play them back on
your DVD-Video players and computer DVD-ROM drives
Then you will need a personal computer with a DVD recordable drive and
a video editing and DVD authoring software package. Take a look at our answers to these frequently asked questions
(FAQs). We provide answers there on how to do these last
two tasks. Standalone DVD recorders are not up for these last two tasks.
They are, however, more adept at replacing the VCR in the role of time shifting TV programs.
So which is the best recordable DVD format? Well that really
depends too... You didn’t think it would be that easy, did you?
For a standalone DVD recorder, we think the DVD-R/RW is the best format.
Here is why. The ability to share a recordable DVD disc with families and friends
(and their ability to play it back on their DVD-Video player or computer
DVD-ROM drive) is
important. Therefore, backwards compatibility with existing DVD-Video players and computer DVD-ROM drives is
essential. The write-once DVD-R format reportedly offers a better than
90% backwards compatibility rate. If this is true, it is clearly the best format for sharing your home video
collection. In comparison, DVD+R runs a close second, with an expected backwards compatibility
rate of about
85%. DVD-RAM is a non-starter, with its radically
different design optimized for computer data storage.
For time shifting of TV programs, you want a rewritable format, so you can
make repeat re-recordings and reuse the disc. For this purpose, any of the rewritable formats (DVD-RW, DVD+RW, and DVD-RAM)
is fine. However, if you want to share your recording of this week’s “Survivor” or “Fear Factor” with
family or friends, you will stand the best chance with DVD-RW.
Therefore, if we had to choose one format,
we would choose the DVD-R/RW format. Here is where things
can get interesting... what if you can choose two out of three formats? The
early standalone DVD recorders used a single format. They recorded to DVD-R/RW, or DVD+R/RW, or DVD-RAM
media. Nowadays, some DVD recorders are offering multi-format record
compatibility. For example, the Panasonic DMR-E50 and Panasonic DMR-HS2
recorders offer rewritable DVD-RAM and write-once DVD-R
recording. The Sony RDR-GX7 recorder can record to DVD-R/RW and
DVD+R/RW. Now that some DVD recorders offer multiple format compatibility
, it is better to choose from these multi-format machines. Think of it
as a way to hedge your bet against obsolescence, as there’s no guarantee that the DVD-R/RW format will
in fact be the winner of this three-way recordable DVD format war. But
which two recordable DVD formats should you choose? For standalone
DVD recorders, we would choose DVD-R/RW and DVD+R/RW. We rule out
DVD-RAM, due to its incompatibility with most existing DVD-Video players and
DVD-ROM drives. Between DVD-R/RW and DVD+R/RW, you have a virtual
guarantee that your DVD recorder will be useful for years to come. It is
unlikely that DVD-RAM will emerge as the single format of choice. Though
it is entirely possible that all three formats can coexist in the
marketplace with the advent of “universal” DVD recorders that can record to all
three formats. Only time will
tell.
Between DVD-R/RW and DVD+R/RW, you have a virtual
guarantee
that your DVD recorder will be useful for years to come. So which DVD recorder
should you buy?
Well, that the subject of the
next article, our DVD Recorder Buying
Guide.
Editor's
Note: As a computer recordable DVD drive, DVD-RAM makes a compelling case with
its true random access design and defect management capability. Because
of this, DVD-RAM seems to have a leg up in the professional and business
computer market.
However, the home computer market is another story. In our opinion, it
is too early to
tell how the computer recordable DVD drive market will play out.
Notation: Throughout this web site and in this article, we use 1 GB to mean 1,000,000,000
bytes. Likewise, 1 Mbps is 1,000,000 bits per second. These are not the computer usage where 1 Kilobyte = 1,024 bytes.
For more info, visit (the following links open in a new browser window):
-
General
-
DVD-R/RW
-
DVD+R/RW
-
DVD-RAM
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