Adobe AFTER EFFECTS 5.5 Help Manual page 46

Adobe After Effects Help
Using Help | Contents
To have After Effects determine the correct settings, click Guess 3:2 Pulldown.
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If you know the phase of the 3:2 pulldown, choose it from the Remove Pulldown pop-
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up menu.
About D1, DV, and various pixel aspect ratio footage
Pixel aspect ratio specifies the ratio of width to height of one pixel in an image. Frame
aspect ratio describes the ratio of width to height in the frame dimensions of an image. For
example, D1 NTSC has a pixel aspect ratio of 0.9 (or 0.9 width by 1.0 height). It also has a
frame aspect ratio of 4:3 (or 4.0 width by 3.0 height).
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A 4:3 frame aspect ratio (left), and a wider 16:9 frame aspect ratio (right)
Some video formats output the same frame aspect ratio but use a different pixel aspect
ratio. For example, some NTSC digitizers produce a 4:3 frame aspect ratio, with square
pixels (1.0 pixel aspect ratio), and a resolution of 640 x 480. D1 NTSC produces the same
4:3 frame aspect ratio but uses rectangular pixels (0.9 pixel aspect ratio) and a resolution
of 720 x 486. D1 pixels, which are always rectangular, are vertically oriented in systems
producing NTSC video and horizontally oriented in systems producing PAL video.
If you display rectangular pixels on a square-pixel monitor without alteration, images and
motion appear distorted; for example, circles distort into ovals. However, when displayed
on a broadcast monitor, the images will be correct.
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A. Square pixels and 4:3 frame aspect ratio B. Nonsquare pixels and 4:3 frame aspect ratio
C. Nonsquare pixels displayed on a square-pixel monitor
When you import D1 NTSC or DV source footage into After Effects, the image looks slightly
wider than it does on a D1 or DV system. (D1 PAL footage looks slightly narrower.) The
opposite effect occurs when you import anamorphic footage using D1/DV NTSC
Widescreen or D1/DV PAL Widescreen. Widescreen video formats have a frame aspect
ratio of 16:9.
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Preparing and Importing Footage
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