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DVD Technical Details 99<br />
tion is not widely available. Therefore, no anamorphic movies have been<br />
released with auto pan and scan enabled, although a few discs use the pan<br />
and scan feature in menus so that the same menu video can be used in<br />
both widescreen and 4:3 mode. In order to present a quality full-screen<br />
picture to the vast majority of TV viewers yet still provide the best experience<br />
for widescreen owners, some DVD producers choose to put two versions<br />
on a single disc: 4:3 studio pan and scan and 16:9 anamorphic.<br />
The playback of widescreen material can be restricted by the disc producer.<br />
Programs can be marked for the following display modes:<br />
• 4:3 full frame<br />
• 4:3 letterbox (for sending a letterbox expand signal to a<br />
widescreen TV)<br />
• 16:9 letterbox only (the player is not allowed to pan and scan on<br />
a 4:3 TV)<br />
• 16:9 pan and scan only (the player is not allowed to letterbox on<br />
a 4:3 TV)<br />
• 16:9 letterbox or pan and scan (the viewer can select pan and scan<br />
or letterbox on a 4:3 TV)<br />
You can usually tell if a disc contains anamorphic video if the package<br />
says “enhanced for 16:9 widescreen” or something similar. If all it says is<br />
widescreen, it may be letterboxed to 4:3, not 16:9. Widescreen Review has<br />
a list of anamorphic DVD titles.<br />
Additional explanations of how anamorphic video works can be found on<br />
the Web at Greg Lovern’s What’s an Anamorphic DVD? page, Bill Hunt’s<br />
Ultimate Guide to Anamorphic Widescreen DVD, David Lockwood’s What<br />
Shape Image?, and Dan Ramer’s What the Heck Is Anamorphic?. More<br />
information can be found at the Anamorphic Widescreen Support Page and<br />
the Letterbox/Widescreen Advocacy Page. You might also be interested in<br />
Guy Wright’s The Widescreen Scam. See <strong>Chapter</strong> 1 for further discussion<br />
of letterboxing.<br />
Anamorphosis causes no problems with line doublers and other video<br />
scalers, which simply duplicate the scan lines before they are stretched out<br />
by the widescreen display.<br />
For anamorphic video, the pixels are fatter. Different pixel aspect ratios<br />
(none of them square) are used for each aspect ratio and resolution; 720pixel<br />
and 704-pixel sizes have the same aspect ratio because the first<br />
includes overscan. Note that conventional values of 1.0950 and 0.9157 are<br />
for height and width (and are tweaked to match scanning rates). The following<br />
minitable uses less confusing width/height values (y/x � h/w).
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