Adobe After Effects CS3 - Manual (Page 66)

AFTER EFFECTS CS3
User Guide
61
If the selected composition includes items that are turned off (that is, the Video or Audio switch is deselected in the
Timeline panel), the Reduce Project command does not remove those items.
If an expression in a selected composition refers to an element in a nonsubordinate composition, Reduce Project
removes the nonsubordinate composition and the applied expression. A message appears after you choose Reduce
Project to remind you of this possibility, so you can undo the command if needed. To avoid removing the expressions
from a nonsubordinate composition, drag the nonsubordinate composition into the composition that refers to it.
Then deselect the Audio and Video switches for the composition that you added.
Work with placeholders and proxies
When you want to temporarily use a substitute for a footage item, use either a placeholder or a proxy.
Placeholder A still image of color bars used to temporarily take the place of a missing footage item. Use a placeholder
when you are building a composition and want to try out ideas for a footage item that is not yet available. After Effects
generates placeholders automatically, so you do not have to provide a placeholder footage item.
Proxy Any file used to temporarily replace a footage item, but most often a lower-resolution or still version of an
existing footage item used to replace the original. Often, storyboard images are used as proxies. You can use a proxy
either before you have the final footage or when you have the actual footage item but you want to speed up
previewing or rendering of test movies. You must have a file available to use as a proxy.
Any masks, attributes, expressions, effects, and keyframes that you apply to the layer are retained when you replace
its placeholder or proxy with the final footage item.
In the Project panel, After Effects marks the footage name to indicate whether the actual footage item or its proxy is
currently in use:
• A box containing a black square indicates that a proxy item is currently in use throughout the project; the name
of the proxy appears in boldface in the project list.
• An empty box indicates that the actual footage item is in use throughout the project.
• No box indicates that no proxy is assigned to the footage item.
Proxy items in Project panel
A. Proxy assigned and in use B. Proxy assigned, but original in use C. No proxy assigned D. Proxy name
See also
“Work with render settings” on page 597
“Use a post-render action” on page 602
A
D
B
C