Adobe AFTER EFFECTS 5.5 Help Manual page 9

Adobe After Effects Help
Using Help | Contents
NTSC (29.97) drop-frame timecode
When you work with a composition that is set to a frame rate of 29.97 fps, After Effects
uses SMPTE 30-fps drop-frame timecode by default, making adjustments using the
SMPTE-standard method of renumbering the first two frame numbers of every minute,
except at every tenth minute. For example, the frame after 59:29 is labeled 1:00:02 instead
of 1:00:00. Non-drop-frame timecode is also available. In both cases, frames are not
discarded or skipped; they are merely numbered differently.
After Effects displays drop-frame timecode by using semicolons between the numbers
and displays non-drop-frame timecode using colons between the numbers. In the Project
Settings dialog box, you can choose how 29.97-fps compositions and footage display their
timecode. See "Setting time-display options" on page 9.
Duration
Each video footage item, layer, and composition in a project has its own duration.
Duration determines the beginning and ending times of the timelines in the Footage,
Layer, and Timeline windows. It is important to notice which duration you are viewing
while you edit in multiple windows. See "Understanding trimming" on page 81 and
"Positioning a layer in time" on page 76.
Frames and fields
Each frame in an interlaced video source is made up of fields. It's important not to confuse
frames with fields. For video, every frame contains two interlaced fields. If you want to use
interlaced video as source footage, you'll usually want After Effects to separate the inter-
laced fields. Separating fields ensures maximum image quality when you apply anima-
tions and effects to video that was originally interlaced. If you're producing a movie for
videotape, you can render the composition to fields in a process known as field-rendering.
See "Interlaced and noninterlaced footage" on page 40 and "Field rendering" on page 44.
Setting time-display options
After Effects supports several methods of measuring and displaying time. The method you
choose applies to time display in the current project and in any subsequent project you
create. Changing the method does not alter the frame rate of footage or a composition—
it changes only how frames are numbered. You can choose from three time-display
options:
Timecode, which counts frames in frames per second (hours, minutes, seconds, frames).
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Frames, which counts frames of footage without reference to time.
•
Feet and Frames, which counts feet of 16mm or 35mm motion-picture film, and counts
•
fractions of feet in frames; 35mm film has 16 frames per foot, and 16mm film has 40
frames per foot.
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A. Timecode B. Frames C. Feet and Frames
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Working with Projects, Windows, and Palettes
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