After Effects has an interesting animation option, where you can manually animate an object/layer or footage in a frame-by-frame fashion, similar to the way that you would animate an object under a camera and photograph successive movements frame-by-frame. To do this, you will set a Hold keyframe at a point in the Timeline, move along a couple of frames, and then move the object/layer in the Composition Window. By repeating the action and forging ahead, moving along in the Timeline and progressing in the Composition Window, you will create a movement phrase, where you will set all of the keys and in-between positions yourself. In this case, After Effects will not interpolate the moves between keyframes.
To begin, follow the steps above to set an initial keyframe on the Timeline; for example, to animate the Position of an object, set a keyframe at Frame 0 on the layer. After Effects will apply a default Linear keyframe, with a diamond-shape icon on the Timeline.
Locate the Linear keyframe icon with your mouse, context-click on the keyframe (right-click or Mac control-click) and choose Toggle Hold Keyframe. By doing this, you will remove After Effects’ interpolation between keyframes. The diamond-shape keyframe icon should then turn into a part-diamond, part-square shape (diamond on the left-side, square on the right-side).
From now on, After Effects will not figure out the in-betweens for you; you will be able to set the calibrations yourself, just as you would with drawn or object animation.
Go to the next point where you want to set a keyframe in the Timeline. If you would like to animate an object/layer with double-frames, an easy way to move forward is to simply click on the Page Down Key in the numeric keypad.
- Page Down Key = Moves the Time Marker forward in the Timeline by 1 frame
- Page Up Key = Moves the Time Marker backward in the Timeline by 1 frame
Again, using Position animation as an example, once you have placed the Time Marker where you want it in the Timeline, you can use the Selection Tool to move the object/layer in the Composition Window, or adjust the x-axis and y-axis coordinates of the object/layer in the Position section of the layer’s Transform options. By doing this, you will set another Hold keyframe in the Timeline.
A Hold Keyframe is signified by a square-shape in the Timeline.
N. B. Using this frame-by-frame animation method, you do not have to click the “add keyframe” icon to set additional keyframes; After Effects will do it for you. All that you have to worry about is to go to a new position in the Timeline — i.e., click the Page Down Key twice to move forward two frames — and then change the position of the layer/footage by either moving the object in the Composition Window or adjusting the Position’s x- and y-coordinates.
After each move, After Effects will place an [x] in the Composition Window, to mark the calibration you have just made, and connect the marks with a line, to indicate a motion path. These are reference marks and will not appear in the project, but you will probably find the marks useful, as you compose the object’s motion path.