DVD Demystified

DVD Comparison
363
Features. Beyond the basic VCR features of play, pause, step, slow, fast,
fast forward, and rewind, DVD adds instant rewind, high-speed scan,
instant search, multistory branching, parental control, multiple camera
angles, video menus, interactivity, and more. Not all discs include these features,
but they are part of the basic DVD format.
Convenience. Discs can be more compactly stored and can be sent
through the mail more easily and cheaply. DVD players can be portable and
battery-powered, at a size only slightly larger than the disc itself. DVD jukeboxes
can put hundreds of discs at push-button access in a very small box.
Durability. Videotapes are subject to degradation from wear and stretching,
erasure from magnetic fields, and damage from heat. DVDs never wear
out, are impervious to magnetic fields, and are less susceptible to heat
damage. Discs can be scratched, but as with CDs, only large scratches will
cause noticeable playback problems.
“Tape eating” VCRs eventually may become something to reminisce
about, like the hazards of being covered with soot after a train ride behind
a coal-fired engine. It is possible that loose material or a defect in a DVD
player could scratch a DVD, but this has been very infrequent with millions
of CD players.
VCR owners who rent videos subject their machines to tapes of dubious
history covered with unknown substances, thus requiring more frequent
head cleanings. Frequently rented tapes are recognized easily by
their excessive glitches and tracking problems. Since the laser head in a
DVD player never touches the surface of a disc, the condition of the disc
does not affect the player so long as the disc is not broken or severely
warped. DVDs are doing well in the rental market because their overall
durability, ease of use, and superior video outweigh their susceptibility to
scratches.
VCRs generally break down because of mechanical failure exacerbated
by rewinding. DVD players have much simpler mechanisms and never need
to rewind.
Audio. Videotape audio is analog. The amount of tape dedicated to the
audio track in monophonic VHS and linear stereo VHS is only one-half of
one percent. Hi-fi VHS uses more tape and a helical scan to get close to CDquality
audio. Dolby Surround encoding can be used to matrix two surround
channels into the videotape stereo signal. In comparison, DVD includes up
to eight audio tracks of CD-quality audio with Dolby Digital or DTS discrete
5-channel surround sound and a subwoofer channel. PCM tracks can