DVD Demystified

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Chapter 3
see the unchanged anamorphic picture, making Hardy look like Laurel.
You are not supposed to do this, but just as there are no “mattress tag
police,” there are no “aspect ratio police” to come and take your player
away.
How It Wasn’t Done with DVD. There are other possible solutions for
dealing with widescreen video that could have been used. DVD could have
stored the full-width, undistorted image, but this would have used up more
storage space 21 and would have required reducing the amount of video on
a disc or reducing the video quality.
Another option would have been to always letterbox the video before
storing it on DVD. The problems with this approach are that vertical information
would have been lost, and storage space that could have held picture
information would have been used to hold black mattes instead. A few
widescreen films are put on DVD this way, usually because a letterboxed
transfer from film to video is available and either the original elements are
no longer available or the studio does not want to pay for a new anamorphic
transfer.
Variable anamorphic squeeze also could have been used. The wider the
video, the more it would be squeezed. The advantage to this approach is
that every pixel of video storage space would be used to hold video, no matter
its shape. The problem is that more expensive circuitry would be
required to handle multiple squeeze ratios.
The designers of DVD chose the reasonable compromise of using the
anamorphic technique to fit the most amount of information into the standard
television image space, and they settled on the standard 16:9 wide
aspect ratio (see “Why 16:9?” following). Having the DVD player shrink the
anamorphic picture vertically for letterbox display on a 4:3 TV gives the
same result (and the same information loss) as shrinking and letterboxing
the picture before storing it on the disc, yet preserves more picture information
for widescreen TVs.
Unfortunately, there is no standardized package labeling for anamorphic
DVDs. The following terms are all used to mean the same thing: enhanced
for widescreen TVs, enhanced for 16:9 TVs, 16:9, 16:9 fullscreen version,
widescreen 16 � 9, anamorphic video, anamorphic widescreen, 1.78 edge-toedge,
and widescreen. In general, look for the word enhanced or anamorphic.
21 Thirty-three percent more, to be exact, since 1.78 is 33 percent larger than 1.33. Even more data
would be needed to store movies in their original aspect ratio. Most movies have an aspect ratio
of 1.85, which would require 39 percent more data. Panavision and Cinemascope movies with a
2.35 ratio would require 76 percent more data.