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What is DVD? Either "Digital Video Disc" or "Digital
Versatile Disc" depending on your preference. The keyword is
"digital", which means that, unlike VHS tapes, both the
picture and sound quality of a DVD are as good as the original master
copy and will not degrade after repeated playing.
A DVD is the same size as a CD but has a much greater storage capacity,
thus allowing it to play full-length movies and carry lots of unique
extra features too. You can get single discs with just the film
plain and simple, or multiple-disc sets such as Gladiator for example,
which has an additional disc crammed full of extras including documentaries,
behind-the-scenes footage, an audio commentary by the director and
deleted scenes among other goodies.
But if you've just got a DVD player, or even if you're still thinking
about taking the plunge, you might feel a little daunted by the
technical jargon. Despair no more. If you don't know your anamorphic
from your academy ratio, your DTS from your Dolby Digital, Amazon.com's
handy guide to DVD jargon will ensure that you won't need a technical
manual to get the most out of DVD.
Anamorphic
Simply put, if you own a widescreen TV and play an anamorphic
DVD the image is expanded to fill the full frame without any loss
of picture. This does away with the need for letterboxing most widescreen
films (CinemaScope movies--see under "Ratios"--are still
too wide to abandon letterboxing completely). Even if you don't
own a widescreen TV, anamorphic prints of films are a better bet
because they are almost always better quality.
Double-Sided & Dual-Layer
Discs
Potentially every DVD can carry information on both sides of the
disc. Each side has two layers, one semi-transparent so the laser
can "see" through it to the layer below. Practically though,
most films can comfortably be stored on one side of a disc, and
even longer features with extras can usually be accommodated by
using both layers.
Notoriously, certain discs, usually older ones, only use one layer
on each side and need to be turned over halfway through the film.
These are known as "flippers" and should be avoided.
DVD
Either "Digital Video Disc" or "Digital Versatile
Disc" depending on your preference, a DVD is the same size
as a CD but has a much greater storage capacity, thus allowing it
to play full-length films and carry lots of unique extra features
too.
A single-side, single-layer DVD has a 4.7-gigabyte (GB) capacity,
seven times greater than that of a CD. This is the data-storage
equivalent of a 133-minute film. Even with all the extra features,
most films will fit comfortably on a single-layer DVD. Single-side,
dual-layer discs have a capacity of 8.5GB, while double-sided, dual-layer
discs can carry a massive 17GB. See also "Double-Sided &
Duel-Layer Discs" and "DVD-ROM"
DVD-ROM
The increased storage capacity of DVD compared with CD makes it
ideal for multimedia applications (eg: high-definition computer
games). Increasingly, film DVDs have a DVD-ROM component allowing
home-cinema buffs to access even more extra features by putting
the disc in the DVD-ROM drive of their PC.
MPEG
MPEG encoding (developed by the Motion Picture Experts Group, hence
the acronym) is the data compression system used for transferring
film to DVD. It is based on the idea that from frame to frame of
a film there are certain elements that remain the same: less data
is required for these redundant details while more data is reserved
for complex details such as rain, smoke, crowd scenes, etc.
Ratios
Widescreen
The standard "widescreen" cinema ratio is 1.85:1--which
just means that the picture you see on a cinema screen is 1.85 times
wider than it is tall. CinemaScope or Panavision films are wider
still, typically with a ratio of 2.35:1.
Standard vs. Widescreen TV
The standard TV ratio is 1.33:1 (the old "academy" cinema
standard) or 4:3, i.e., 4 units wide to three tall. Thus "widescreen"
films made for cinema release have to be letterboxed to allow the
wider picture to fit on the almost square TV screen. Widescreen
TVs are designed to allow films to be shown in a ratio closer to
their theatrical format and have a width-to-height ratio of 16:9,
which works out as 1.77:1 (i.e. almost but not quite cinema width).
Anamorphic DVDs (see above) have banished most letterboxing for
anyone who owns a widescreen TV by automatically formatting the
picture to fit the TV ratio (CinemaScope movies still require some
letterboxing).
Very few modern films (with some notable exceptions such as The
Blair Witch Project and Eyes Wide Shut) are intended to be seen
in the TV-sized 4:3 ratio, so a DVD formatted like this is usually
a cropped "pan & scan" image in which up to 33 per
cent of the cinema picture is lost.
Region Coding
Most DVDs are region coded and theoretically only playable on machines
with the same region code. Thus in Britain and Europe, DVDs are
Region 2 encoded, and will not work on players set up to play Region
1 (North American) discs.
Region coding was introduced at the insistence of the film studios
to control their global release schedules. The world was divided
into eight different regions: Region 2 covers all of Europe, Japan,
the Middle East and South Africa. These are the DVDs available from
Amazon.co.uk. Region 1 discs (Canada and the U.S.A.) are available
from Amazon.com's DVD store
Surround Sound Systems
These come in various guises on DVD, most commonly Dolby Surround,
Dolby Digital 5.1 and DTS.
Dolby Surround
Dolby Surround uses five channels: front left, front right, centre,
left surround and right surround.
Dolby 5.1
Dolby 5.1 has an extra sixth channel for "rumbling" low-frequency
effects. This "LFE" channel is referred to as ".1"
DTS
DTS is an acronym for "Digital Theater Systems". As with
Dolby 5.1 it uses six discrete channels (five plus a subwoofer for
the low stuff), but is claimed to be an improvement over Dolby as
the sound across all channels is digitally encoded, ensuring flawless
reproduction.
VHS
An outmoded format, soon to go the way of eight-track cartridges. |
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