Chapter 1

DVD Technical Details 97
TVs. Some movies, especially animated features and European films, have
an aspect ratio of 1.66, which can be letterboxed for 1.33 display or sideboxed
(windowboxed) for a 1.78 display.
Pan and scan means the thinner TV “window” is panned across the
wider movie picture, chopping off the sides. However, most movies today
are shot soft matte, which means a full 1.33 aspect film frame is used. (The
cinematographer has two sets of frame marks in his or her viewfinder, one
for 1.33 and one for 1.85, so he or she can allow for both formats.) The top
and bottom are masked off in the theater, but when the film is transferred to
video, the full 1.33 frame can be used in the pan and scan process. Pan and
scan is primarily used for 1.33 formatting, not for 1.78 formatting, because
widescreen fans prefer that letterboxing be used to preserve the theatrical
effect. For more details and nice visual aids, see Leopold’s How Film Is
Transferred to Video page (www.cs.tut.fi/~leopold/Ld/FilmToVideo/). A list of
movie aspect ratios is at The Widescreen Movie Center (www.widemovies.com).
Once the video is formatted to a full-screen or widescreen format, it’s
encoded and stored on DVD discs. DVD players have four playback modes,
one for 4:3 video and three for 16:9 video:
• Full frame (4:3 video for 4:3 display)
• Auto letterbox (16:9 anamorphic video for 4:3 display)
• Auto pan and scan (16:9 anamorphic video for 4:3 display)
• Widescreen (16:9 anamorphic video for 16:9 display)
Video stored in 4:3 format is not changed by the player. It appears normally
on a standard 4:3 display. Widescreen systems either enlarge it or add
black bars to the sides. 4:3 video may have been formatted with letterboxing
or pan and scan before being transferred to DVD. All formatting done to
the video prior to it being stored on the disc is transparent to the player. It
merely reproduces it as a standard 4:3 TV picture. Video that is letterboxed
before being encoded can be flagged so that the player will tell a
widescreen TV to automatically expand the picture. Unfortunately, some
discs (such as Fargo) do not flag the video properly, and worse, some players
ignore the flags.
The beauty of anamorphosis is that less of the picture is wasted on letterbox
mattes. DVD has a frame size designed for a 1.33 display, so the
video still has to be made to fit, but because it’s only squeezed horizontally,
33 percent more pixels (25 percent of the total pixels in a video frame) are
used to store an active picture instead of black mattes. Anamorphic video
is best displayed on widescreen equipment, which stretches the video back