Adobe After Effects CS4 - Manual (Page 252)

246 USING AFTER EFFECTS CS4
Animation and keyframes
Last updated 12/21/2009
Current Frame Holds the layer at the position of the current-time indicator (also the frame displayed in the
Composition panel), and time-stretches the layer by moving the In and Out points.
Layer Out-point Holds the ending time of the layer at its current value and time-stretches the layer by moving its In
point.
Time-stretch a layer to a specific time
1 In the Timeline panel, move the current-time indicator to the frame where you want the layer to begin or end.
2 Display the In and Out columns by choosing Columns > In and Columns > Out from the Timeline panel menu.
3 Do one of the following:
• To stretch the In point to the current time, press Ctrl (Windows) or Command (Mac OS) as you click the In time
for the layer in the In column.
• To stretch the Out point to the current time, press Ctrl (Windows) or Command (Mac OS) as you click the Out
time for the layer in the Out column.
Time-stretch a layer but not its keyframes
When you time-stretch a layer, the positions of its keyframes stretch with it by default. You can circumvent this
behavior by cutting and pasting keyframes.
1 Make a note of the time at which the first keyframe appears. (Placing a composition marker is a good way to mark
the time.)
2 In the Timeline panel, click the name of one or more layer properties containing the keyframes you want to keep
at the same times.
3 Choose Edit > Cut.
4 Move or stretch the layer to its new In and Out points.
5 Move the current-time indicator to the time at which the first keyframe appeared before you cut the keyframes.
6 Choose Edit > Paste.
Reverse the playback direction of a layer
When you reverse the direction at which a layer plays back, all keyframes for all properties on the selected layer also
reverse order. The layer itself maintains its original In and Out points relative to the composition.
Note: For best results, precompose the layer and then reverse the layer inside the precomposition. For more information
on this process, see “
About precomposing and nesting ” on page 60.
1 In a Timeline panel, select the layer you want to reverse.
2 Choose Layer > Time > Time-Reverse Layer, or press Ctrl+Alt+R (Windows) or Command+Option+R (Mac OS).
Reverse keyframes without reversing layer playback
You can select and reverse keyframes across multiple layers and properties, but each set of keyframes for a property is
reversed only within its original time range and not that of any other selected property. Markers in the Timeline panel
are not reversed, so you may need to move markers after reversing keyframes.
1 In the Timeline panel, select a range of keyframes you want to reverse.
2 Choose Animation > Keyframe Assistant > Time-Reverse Keyframes.