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Sure, it would be nice to be on the cutting edge of technology
and also have everything running smooth, but by definition the cutting edge
isn’t smooth. Nowhere is this more apparent than in the profusion of standards
for DVD-video and DVD-ROM. In this tip we will attempt to reduce some of the
turmoil in the subject.
Pre-recorded DVDs come in two sizes, 80mm and 120mm (same
size as the standard CD). As our first step in simplification we are going to
ignore the 80mm size (DVD 1-4) and focus on the 120mm formats most commonly used
for DVD-ROM. There are five formats to be concerned with that vary primarily in
the number of data layers and whether they can accept data on both sides of the
disc.
|
Format |
Sides |
Layers |
Data Capacity |
MPG-2 Video |
|
DVD-5 |
Single |
Single |
4.7GB |
2.2 hrs |
|
DVD-9 |
Single |
Double |
8.5GB |
4.0 hrs |
|
DVD-10 |
Double |
Single |
9.4GB |
4.4 hrs |
|
DVD-14 |
Double |
Both |
13.2GB |
6.3 hrs |
|
DVD-18 |
Double |
Double |
17.1GB |
8.0 hrs |
8.0 hrs |
When you rent or buy a movie on DVD today it will most
likely be DVD-9, although older films and a few newer ones will be found on
DVD-5. The other three formats are emerging technologies used in the video
industry, that may or may not find their way into the retail market.
Just about all DVD players today support both DVD-5 and
DVD-9, and will also play CDs. However, if you want to play CD-Rs and DVDs on
the same unit, make sure you get a player that is labeled “dual optics” or “twin
laser” or something similar (In most cases, the player will state on the box
what types of media it will support ). That’s because CD-R uses a different
frequency of laser, and most DVD players will not read CD-Rs well unless there
is a second laser for that purpose. Or you could get a combo drive, designed to
read DVDs but also to read and write CD-R or CD-RW.
The standards for recordable DVD are a different story
altogether, because there are four versions right now fighting for industry
supremacy and of course they are not compatible. If you invest in the wrong one
it will soon be out in the garage with your old Betamax recorder and that
collection of 8-track tapes.
At the moment DVD-R holds the lead for one-time recordable
DVD discs, and the two front-runners in re-writable DVD are DVD-RW and DVD+RW.
If we had to place a bet on one or the other it would probably be DVD+RW because
it provides the greatest compatibility, for both video and data recordings. A
recent test showed DVD-RW to be compatible with just over 70% of the players on
the market. Also recently available are DVD-ROM recorders that support DVD+R/RW
AND DVD-R/RW formats for maximum compatibility.
|
Format |
Sides |
Layers |
Data Capacity |
MPG-2 Video |
|
DVD-R1.0 |
Single |
Single |
3.95GB |
1.9 hrs |
|
DVD-R2.0 |
Single |
Single |
4.7GB |
2.2 hrs |
|
DVD+R1.0 |
Single |
Single |
4.7GB |
2.2 hrs |
Now that prices on DVD recorders have dropped from
thousands of dollars to less that $250 for an adequate model, you may be
thinking it would be nice to back up some of the expensive DVD movies your kids
are playing around the clock. If you look at the tables above, you will notice
that none of the recordable DVD formats are double-sided, and the maximum
capacity is 4.7GB. A little basic arithmetic will tell you that a DVD-9 movie
just isn’t going to fit, but there are some options available.
First, if you copy the movie only and omit the extras,
you’ll find that many if not most films will fit nicely on a 4.7GB disc. For
longer films, compression is an option if you are willing to sacrifice a certain
amount of image quality. And of course you can always split the movie onto two
discs, just like the old days at the Main Street movie house. Two reels per
feature, with an intermission.
This all assumes that the original disc isn’t copy
protected. There are several copy protection schemes out there with the most
common being Macrovision, and there are even DVDs copy-protected by country or
region. You may have heard that there are ways to bypass copy protection, but
according to our lawyers you didn’t hear it from us.
Well, we hope this has helped to clear things up rather
than scare you away. No matter how you cut it, DVD is a giant leap from the
700MB / 80 min. limit of CD-RW, and in one form or another DVD is here to stay
for awhile.
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