DVD Today and Tomorrow
Copyright © 2000 Walt Crawford
Originally presented at an
ALA ACRL Program, July 8, 2000
I started writing about DVD in April 1996, not too long after the format was adopted as a compromise standard.
I said at the time that it would probably be important to libraries in "a year or three"--and I'd say
that was a reasonable projection. Today, I'd like to review the basics of DVD, where it is today, its relation
to some other media, and what I think might and might not happen. Let's start out with some broad statements:
- DVD is not laserdisc. It's not likely to go away or become an arcane niche product.
- DVD won't wipe out VHS--at least not anytime soon.
- Making something digital doesn't make it better--but good DVDs do offer much better picture
quality than VHS.
- DVD is not the last word in video distribution. It has nothing to do with HDTV (and very little
to do with DTV). You can't assume the ability to make perfect archival copies--or any copies, for that matter. The DVD label does not assure good picture or sound quality.
- Recordable DVD is here now, getting cheaper, and shows some promise--but it suffers from compatibility
problems and expensive media, and real-time DVD compression is no easy task.
- DVD is a great circulating medium for libraries, ignoring the archival problems.
- As far as I can tell, DVD has no special virtues for network video delivery, and networked delivery
eliminates some of DVD's special virtues.
Now it's on to a quick review of DVD basics, notes on DVD and the marketplace, DVD and libraries, DVD and other
video media, and so on.
A DVD is a "fancy CD"--a laser-read stamped disc, 12cm in diameter, containing billions of tiny pits
and lands in one very long track. The DVD laser has a shorter wavelength, and the pits and lands are shorter and
narrower, which means that a single-layer DVD can contain 4.7 billion bytes of raw data (4.7 gigabytes):
seven times the capacity of a CD.
Many DVDs have two information layers on one side, one layer semitransparent. These discs, called DVD9 in the
industry, can hold roughly 9 gigabytes. All DVD and DVD-ROM drives can read dual-layer discs, and on modern drives
the transition from one layer to the other is transparent.
Some DVDs are two-sided, typically carrying the full-width version of a movie on one side and a panned-and-scanned
"screen-filling" version on the other. No current DVD player, as far as I know, can play both sides automatically;
you have to flip the DVDs. A two-sided DVD can hold up to 17GB of data.
A single-layer DVD can hold more than two hours of video accompanied by multichannel CD-quality sound thanks
to MPEG2 compression. According to what I've read recently, typical compression is 36 to 1. Thus, less than 3%
of the original video data is stored.
MPEG2 compression works two ways. Intraframe compression reduces repetitive data within a single picture, such
as areas of a single solid color; interframe compression takes advantage of the fact that most moving images don't
change much from one frame to the next. Most DVD frames are stored as differences or deltas from the preceding
frame, with full "key" frames stored when there are dramatic changes, or often enough to make the mechanics
You might assume that dual-layer DVDs are only for very long movies or for movies stored in more than one version.
Not necessarily. Disney, for example, releases some relatively short films on dual-layer DVDs to use less compression
and a higher average bit rate, potentially yielding a better picture.
Many (perhaps most) DVDs offer extras--scenes deleted from a film, trailers, alternate language sound tracks,
or alternate sound tracks containing commentaries by directors or stars. Some DVDs even include alternate camera
angles for certain scenes, but these are mostly so-called adult videos.
DVD in the Marketplace
DVDs have been around for four years, widely publicized for three years or so, and widely available for two
years. At the beginning of this year, U.S. consumers owned roughly five million DVD TV players and 30 million DVD-ROM
drives on PCs; that represents very strong growth for a young medium. In February 2000, six thousand DVD titles
were available in the U.S., nine thousand worldwide. Unlike audio CDs but like videocassettes, DVDs aren't universally
playable. Order a DVD from France, and you probably won't be able to play it on your U.S. set-top box or DVD-ROM
DVD discs and players have achieved fairly complete market saturation. Target and Kmart sell DVD players and
discs; Columbia House has a DVD club. You can buy $170 name-brand DVD players, $250 Sony players, and $13 DVDs
of some recent films. Those are all numbers that suggest that DVD is becoming a true mass medium: players costing
less than $200 and discs costing less than $25. Five percent household penetration may not be fabulous, but for
a three-year-old medium it's remarkably good.
Although there's a strong DVD rental market, studios have not used the multitiered pricing with DVD that they
do with VHS: that is, an initial release at $90-$100 followed by a rerelease at $20 after a year or so. Most new
DVDs sell for $20 to $24, and most studios release DVD versions simultaneously with VHS.
A dual-layer DVD can hold more than four hours of video, and we're beginning to see some great video collections
on DVD. For example, most seasons of The Avengers are out in reasonably priced boxes, as is all of Monty
Python's Flying Circus. We're likely to see a lot more of this, and we're likely to see many more specialty
videos, ones that may be particularly suitable for libraries. DVD's combination of high-quality video and high-quality
sound has resulted in quite a few concert DVDs, both popular and classical.
The low end of the market is there already. Madacy, a Canadian firm that specializes in cheap sets of audio
CDs frequently offering low-quality sound now seems to be producing cheap sets of DVDs offering low-quality video.
But there are, and will be, DVD equivalents of Rhino, LaserLight, and Vox--companies producing high-quality special-interest
DVDs at good prices.
DVD mastering is more expensive than VHS mastering or CD mastering, largely because good MPEG2 encoding requires
a two-pass process using equipment and expert personnel currently in short supply. On the other hand, DVD production
should be cheaper than VHS production and only a little more expensive than CD production. Effective DVD mastering
requires high-quality video or film to start with, for at least two reasons. One, DVD's higher quality makes flaws
more obvious. Two, some common flaws in mediocre source material will interfere with compression, leading to more
new artifacts--for example, random noise or snow in a picture makes compression incredibly difficult, because it
results in much greater frame-to-frame differences.
DVD in the Library
DVDs are great for libraries. DVD offers a more durable video storage medium than videocassettes. As with CD,
there's no physical contact between the playing head and the disc--and, as with CD, the data surface is protected
by chemically inactive plastic. While DVDs do have higher physical density than CDs, DVDs also have superior error
correction. We don't really know how DVDs will stand up to years of rough handling by library patrons, but it's
reasonable to believe that they will hold up quite well, and certainly much better than VHS.
DVDs offer the film as it was created, not the partial film as seen on VHS, and most feature DVDs offer extras.
For aficionados and film students, the ability to study frames individually and reach any scene rapidly make DVD
a much better study medium.
When it comes to circulation, DVD has the same problems as CDs. You shouldn't label the discs (and can't really
label two-sided discs) except with perfectly-centered labels right around the hole, and the discs don't cooperate
with security systems very well. If you've solved those problems for CDs, you've solved them for DVDs, and the
costs aren't much different. There's really no excuse for charging borrowers a fee for borrowing DVDs, unless
you also charge fees for books and CDs!
I said that DVD wouldn't replace VHS in any great hurry. There are just too many VHS recorders out there; most
people seem to find VHS quality adequate; and VHS recorders are--well--recorders.
You don't need new shelving for DVDs. DVD boxes are like thin VHS boxes and will fit nicely on the same shelves.
DVD producers wanted the boxes to be different than CD jewelboxes so there would be no confusion, and wanted to
make it easy for stores to sell DVDs as well as (or in place of) VHS. That decision serves libraries well.
DVD and Other Media
DVD-ROMs are basically CD-ROMs with a lot more capacity, and they haven't done well despite those 30 million
DVD-ROM drives. That has a lot to do with the depressed state of CD-ROM publishing in general and is also influenced
by the incredible price competition among PC makers. Because CD-ROM drives are a few bucks cheaper than DVD-ROM
drives for makers, we're still seeing six times as many CD-ROM drives as DVD-ROM drives shipped in new PCs. Last
year, I thought there would be hundreds of DVD-ROMs out by the end of this year; at this point, I'd settle for
dozens and may not see even that many.
Every DVD player and DVD-ROM drive can play audio CDs, period--and every DVD-ROM drive can play CD-ROMs. Most
DVD players and drives can read CD-RW (rewritable) discs. Some DVD players and drives can read CD-R discs--but
older ones can't. That's unfortunate, given the explosion in CD-R sales: more than 1.5 billion last year.
Recordable DVD? Three incompatible formats have been announced, but only one has made it to market: DVD-RAM,
a rewritable format that began with 2.6 GB per side but is gaining full DVD capacity. The drives are still $500
or more but getting cheaper; Apple has included DVD-RAM standard on its top-end Mac. Some newer DVD players will
play DVD-RAM discs. The other two formats may be fading away or going into specialized uses; there's some reason
to believe that DVD-RAM will become the dominant recordable standard.
Unfortunately, DVD-RAM discs are expensive ($25 to $30 or more), and real-time MPEG2 compression doesn't work
that well. DVD-RAM doesn't threaten VHS as a home recording medium just yet; in the future, who knows?
There are two incompatible audio-only DVD formats (SACD and DVD-Audio), but I'm not sure that either one will
make much difference.
One persistent myth about DVD is that it has something to do with Digital TV or High-Definition TV, DTV and
HDTV respectively. There's no connection whatsoever; HDTV requires something four times the resolution of DVD.
Will there be a high-definition successor to DVD--call it HDVD? Technologically, it's feasible using blue lasers,
although the prices don't make sense just yet. But if DVD is being adopted rapidly here and abroad, HDTV is turning
out to be an enormous disappointment at least in the United States. Maybe we should have expected that: the government
mandated HDTV as a replacement for analog TV, and that's not the kind of thing government should be involved
in. So far, HDTV seems to be a nonstarter that's resulted in giving away huge chunks of the broadcast spectrum
to the same stations that have used their existing chunks so selflessly--and the plan to take back the existing
chunks has an escape clause wide enough for the QE2.
What about other optical formats? Audio CDs aren't going away; Video CDs never did work. CD-ROMs will morph
into DVD-ROMs, very slowly, since there's total forward compatibility. The rest of the optical formats have
already become true niche products.
I almost hate to mention this one, but most of you won't have heard of it--and, with luck, you'll never have
to worry about it. Remember Divx, the rental DVD from hell? Well, evil never sleeps: now we have a company called
SpectraDisc that wants to introduce DVDs or CDs with a new twist. "Environmentally safe chemistry" would
be used so that the information layer on the disc starts decaying as soon as the packaging is opened. Your disc
is good for 24 hours, 48 hours, or a week--and then it's just a useless chunk of plastic, metal, and chemicals.
Isn't that heartwarming? Think of books printed with ink that disappears after a week or two, or on hyperacidic
paper that turns into ash within a month. I'm hoping that this marvel of new technology will never make it to market--but
if it does, well, you heard about it here. It's a great way for publishers that hate libraries to release DVDs
or CDs that libraries can't use.
Network Delivery: Quick Notes
I don't really have much to say about network delivery of videos, largely because I don't know much about it.
I do know that DVD isn't a magic bullet to make network delivery easier. The video output from DVD, once it's been
decompressed, is on the order of 124 megabits per second (more than 15MB); the actual data stream from the disc
averages about 3.5 mbps, with a combined audio-video maximum of 11mbps (1.32MBps)--but you could only deliver compressed
form if every user station has DVD software and enough CPU power to use it effectively, which basically means dedicated
use of something like a Pentium II-400. The DVD standard doesn't even allow for digital distribution of the decompressed
stream, for that matter: it's explicitly forbidden in the license. So, realistically, you'll be delivering DVD
as regular video, with all the bandwidth problems and quality issues implied by that. Now, someone else on this
program may know enough to challenge my statements, and I'd be happy to hear such a challenge--but this is the
way I understand it.
There's another aspect to network delivery, which another speaker may clarify for me. If you're delivering the
entire video as a stream, you're eliminating the special features of DVD--the ability to study a film frame by
frame, the alternate sound tracks, and so on. That's certainly appropriate for many cases, but it does mean that
a networked DVD is a poor substitute for an actual DVD.
Notes About the Future
I'm not a great believer in broad futurist projections, and I'm not qualified to make them. Here's a little
of what I think is likely to happen or hope will happen, in addition to the future thoughts I've thrown in along
- Expect to see DVD players sell very well--but it's quite possible that market saturation will
be comparable to true high fidelity systems or PCs, rather than the heights of TV and VCRs. That is, unless studios
really do stop releasing movies on VHS and recordable DVD becomes
as cheap and useful as VHS, I wouldn't be surprised to see DVD reach 40 to 55 percent of U.S. households and become
an upgrade-and-replacement market. That's OK: that's enough of the market for libraries to care about. I'd be very
surprised to see it stall at anything below 25 percent unless clown acts like autodestruct DVDs continue to distract
- Nobody knows for sure how DVDs will hold up in heavy use, but I wouldn't be surprised if DVD
longevity approaches CD life. And for those who believed that CDs would only last five or ten years--well, I was
listening to Paul Simon's Graceland as I edited this speech,
and we've had that CD for 14 years.
- The medium itself seems likely to last at least 20 to 25 years: that's typical for a successful
new medium. Note that this means that CDs have a span of at least 40 years thanks to forward compatibility--but
then, LP sales are on the increase and they've been around more than 40 years.
- Right now, it's trivially easy for a library to burn your own CD-Rs, for oral history, local
festivals, or any other purpose. Will you be burning your own recordable DVDs in a few more years? I don't see
why not. Will such recordings be archival? Not at all, any more than any other digital medium.
- Will broadband Web distribution and video on demand doom DVD? I don't think so--but only time
I look forward to hearing the other speakers. I don't work in a library--and, truth to tell, we don't yet own
a set-top DVD player at home. (I've used a few DVDs, but always on my PC.) DVD is the first truly successful new
medium in more than a decade, and it's one with considerable advantages for libraries. It's not magic, but neither
is anything else. I hope the last 20 minutes have offered some useful insights into the state of the medium and
its plausible futures. Thank you.
[Addendum for Web version]
The document above represents the speech as it was written. The speech as given included impromptu comments
and left out portions of what's here.
At the exhibits during ALA Annual 2000, I learned that Naxos (known for high-quality low-price original classical
music CDs) is already producing DVDs--but, while they're fairly priced ($30-$50 for ballet and opera DVDs), they're
not bargain priced.
My challenge in the conclusion and notes about network delivery were based on a slight misunderstanding of the
program title. "DVD and networked video delivery" described separate portions of the program--two speakers
on DVD, two on networked video delivery--rather than a relationship.
July 12, 2000