- Frequently Asked Questions
It is a type of high density compact disc
that can hold from 7 to 14 times as much information as a conventional CD. It can hold
video, audio, or computer data. At the present time, DVDs are used mostly for playing
movies, although computer drives also use DVD-ROM discs.
What do the
letters DVD stand for?
Officially, nothing. But many people
translate the letters as Digital Versatile Disc or Digital Video Disc.
What are the
DVD format types?
The most common ones are:
||Stores 4.7 Gbytes
||Data on 1 side in 1 layer
||Stores 85. Gbytes
||Data on 1 side in 2 layers
||Stores 9.4 Gbytes
||Data on 2 sides in 1 layer
||Stores 17.0 Gbytes
||Data on 2 sides in 2
Why are there
To accommodate different amounts of data.
One side of one disc can hold about two hours worth of video and audio, but of
course some movies are longer than that. Some of the first long movies on DVD needed to be
flipped partway through; new technology allows about four hours of seamless playback on
one two-layer side. In some cases, publishers have put two versions of a movie wide
screen and so-called "pan and scan" on the two sides of a disc, so
purchasers can have a choice. Only about 5 percent to 10 percent of movies are too long to
fit on one side of a DVD disc.
Is a DVD disc
made like a CD?
In many ways, the process is similar, but
there are some big differences. The DVD disc is made of two layers, each half the
thickness of a CD. So when theyre bonded together they are as thick as a CD (1.2
mm). The pits of a DVD disc are half as big, and much more closely spaced, than those of a
CD. That means the laser that "reads" the disc must be smaller and more sharply
Are all DVD
discs compatible with all DVD players?
Generally, yes. For legal reasons, some
publishers encode DVD discs so that they may play only in certain parts of the world. This
is called "regional coding."
Are DVD players
compatible with my television now?
Yes. You just hook it up as you would any
What about High
Definition Television (HDTV)?
At the present time, DVD wont work
with HDTV because its data rates are so much higher.
Do DVD players
play my present CDs too?
What can DVD do
that VHS videotape cant?
To begin with, the picture and sound
quality of DVD are far superior to that of VHS. The discs wont wear out or degrade
over time, as tape will. They cant be accidentally erased. Plus DVDs can have many
extra features such as a choice of languages on the sound track, the ability to play back
favorite sections instantly, special-effects playback (such as slow-motion), the choice of
parental "locks" on objectionable scenes, and in some cases the ability to
select different camera angles, such as in a filmed concert. The audio is better than that
of a CD.
compared with laserdiscs?
The quality of DVD video has generally
been judged better than that of laserdiscs.
Can labels be
printed on DVD discs?
It depends on the type of disc. If it is
single-sided, a label may be printed on the top side. But because DVDs are more
susceptible to heat than CDs are, silk-screening which uses ultraviolet heat
may not be the best choice. Ink also affects the flatness of DVDs more than CDs. So-called
"pit art" was developed to avoid these problems. In it, the pits are recorded
only in some parts of a disc side, in a graphic pattern that gives the appearance of a
design or a label.
If a DVD disc has data on both sides,
neither silk-screening nor pit art may be used on the main surface. The so-called
"mirror band" in the center of the disc may be printed on.
FAQ-Authoring and Replication