Adobe AFTER EFFECTS CS3 PROFESSIONAL User Manual page 70

Note: If you remove 3:2 pulldown from interlaced video footage, After Effects automatically sets the frame rate of the
resulting footage item to four-fifths of the original frame rate. When removing 3:2 pulldown from NTSC video, the
resulting frame rate is 24 fps.
The composition's frame rate should match that of the final output format. In most cases, you can simply choose a
composition settings preset. In contrast, set the frame rate for each footage item to that of the original source footage.
See also
"Work with render settings" on page 591
"Converting movies" on page 623
Change frame rate for a footage item
1 Select the footage item in the Project panel.
Choose File > Interpret Footage > Main.
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3 Select Conform To Frame Rate, enter a new frame rate for Frames Per Second, and then click OK.
Change frame rate for a composition
1 Choose Composition > Composition Settings.
Do one of the following:
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• Choose a composition settings preset from the Preset menu.
• Set the Frame Rate value.
Change pixel aspect ratio
Pixel aspect ratio is the ratio of width to height of one pixel in an image. Frame aspect ratio is the ratio of width to
height of the frame dimensions of an image.
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A 4:3 frame aspect ratio (left), and a wider 16:9 frame aspect ratio (right)
Most computer monitors use square pixels, but many video formats—including ITU-R 601 (D1) and DV—use non-
square rectangular pixels.
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 nonsquare pixels (0.9 pixel aspect ratio) and a
resolution of 720 x 486. D1 pixels, which are always nonsquare, are vertically oriented in systems producing NTSC
video and horizontally oriented in systems producing PAL video.
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User Guide