DVD Demystified

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TABLE A.19 cont.
Video resolution
1. DTV is neither PAL nor NTSC. The values are placed in the NTSC rows for convenience.
2. Wide aspect ratios (1.78 and 2.35) for VHS, LD, and VCD assume a letterboxed picture. For comparison, letterboxed 1.66 aspect ratio resolution is about seven
percent higher than 1.78. Letterbox is also assumed for DVD and DTV at a 2.35 aspect ratio. DVD’s native aspect ratio is 1.33; it uses anamorphic mode for 1.78.
DTV’s native aspect ratio is 1.78.
3. The very rare 1.78 anamorphic LD has the same pixel count as 1.33 LD. Anamorphic LD letterboxed to 2.35 has almost the same pixel count as 1.78 LD (567 �
363). The mostly non-existent 1.78 anamorphic VHS has the same pixel count as 1.33 VHS. Anamorphic VHS letterboxed to 2.35 has almost the same pixel count
as 1.78 VHS (333 � 363). No commercial 2.35 anamorphic format exists and no corresponding stretch mode exists on widescreen TVs.
4. TVL is lines of horizontal resolution per picture height. For analog formats, the customary value is used; for digital formats, the value is derived from the actual
horizontal pixel count adjusted for the aspect ratio. DVD’s horizontal resolution is lower for 1.78 because the pixels are wider. Pixels for VHS and LD are approximations
based on TVL and scan lines.
5. Resolutions refer to the medium, not the display. If a DVD player performs automatic letterboxing on a 1.85 movie (stored in 1.78), the displayed vertical resolution
on a standard 1.33 TV is the same as from a letterboxed LD (360 lines).