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The DVD-Video format has revolutionized the
home entertainment industry by offering image and sound quality
far superior to that of VHS videotape. This impressive digital
format can generate pictures in amazing detail using nearly 500
lines of horizontal resolution! And, it's capable of delivering
six discrete channels of exhilarating audio to create the ultimate
surround sound experience. The DVD format also allows for an
incredible amount of data to be stored on a single disc: up to 17
gigabytes worth!
Thanks to almost 500 lines of horizontal resolution, you'll
immediately appreciate the startling brilliance and clarity of the
picture quality delivered in the DVD-Video format nearly twice
that of standard VHS tapes! And because DVD-Video uses a laser
pick-up system, nothing touches the disc's playing surface. So it
won't wear out. Of course, you don't rewind a disc, which makes it
even more durable.
DVD-Video players are compatible with whatever aspect ratios are
encoded on the DVD-Video disc you're watching. You can play movies
recorded in a 4:3 format (conventional TV proportions), or in
letterbox, which presents an image for panoramic viewing on a
conventional TV. If you own one of the latest 16:9 widescreen TVs,
you can select the widescreen format for maximum impact.
Much like a CD player, a DVD-Video player uses a laser to
translate the microscopic pits that are in the disc, into music,
video or information. But that's where the similarity ends. A DVD-Video
disc holds much more information than a standard CD. Engineers
increased its data-storage capacity by shrinking the microscopic
pits and placing them closer together. However, the standard CD
laser could not read this tightly packed information. A unique
laser, with a thinner beam and shorter wavelength was developed.
Theoretically, the most efficient method to put more information
onto a disc was to construct a disc with two layers of
information. A dual-layer disc stores an astounding 8.5 gigabytes
of information, while a dual-layer, double sided DVD-Video disc
can store as much information as roughly 12,000 floppy discs,
which would create a pile 120 feet high. That's 17 gigabytes worth
of information!
DVD-Video players can also play CDs. In order to make this
possible, a dual-focus hologram lens is used to split the beam of
the already super-fine laser so that it can read two different
depth levels, one for DVD-Video and one for CD or Video CD. Some
players even have two lens.
DVD-Video has the same NTSC vs. PAL problem as videotape and
laserdisc. The MPEG video on DVD is stored in digital format, but
it's formatted for one of two mutually incompatible television
systems.
Some players will only play NTSC discs, some players will only
play PAL discs, and some will play both. All DVD players sold in
PAL countries play both. These multi-standard players partially
convert NTSC to a 60-Hz PAL (4.43 NTSC) signal.
DVD players also feature a system to protect motion picture
studios that want to control the home release of movies in
different countries. Therefore they have required that the DVD
standard include codes that can be used to prevent playback of
certain discs in certain geographical regions or zones. Each
player is given a code for the region in which it's sold. The
player will refuse to play discs that are not allowed in that
zone. This means that discs bought in one country may not play on
players bought in another country.
Regional codes are entirely optional for the maker of a disc.
Discs without codes will play on any player in any country, but
there aren't many of these out there. Some players (often called
world zone players) will play all zones and other units can be
modified to play all zones.
There is also a few forms of copy protection system incorporated
on the discs, the most common is called macrovision. This system
prevent a video recorder to lock on to the DVD picture rendering
the copy unwatchable. If it was not for this system the piracy of
movies would be enormous There are modifications for some units to
turn macrovision off, so its often a good idea to do some research
on the unit you are purchasing if you want a world zone unit or
macrovision free unit.
For info on setting up a DVD player check out our
DVD setup guide.
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