Motion - Working with Keyframes February 11, 2005
Working with Keyframes in Motion, Part 1
Creating and Manipulating KeyframesBy: Mark Spencer
With all the hulabaloo about Behaviors, it's easy to forget that you can use traditional keyframing techniques to create animation in Motion. You can create keyframes for just about any parameter of any object, mask, or effect, and you can manipulate the keyframes in Motion's full-featured Keyframe Editor. However, there are a few quirks in the way Motion handles keyframes that can trip you up - especially if you are used to keyframing in other applications - so let's take a look at how to create and adjust keyframes in Motion while avoiding these pitfalls. This article assumes basic familiarity with the Motion interface and the concept of keyframes. For an overview of navigating the interface with keyboard shortcuts, see my article here.
Creating Keyframes with Record Animation
The quickest and easiest way to set keyframes in Motion is by using the handy Record Animation feature. You enable recording of keyframes by clicking the red Record button, or pressing the keyboard shortcut A. Then, with the object you want to animate selected and the playhead positioned where you want to add a keyframe, you simply change the value of any parameter - that new value is automatically recorded at that frame.
To change transform parameters, such as position, scale, rotation, or anchor point, you can manipulate the object directly in the Canvas (control-click on the object to change to the appropriate tool if needed). For other parameters you can use the Dashboard (press D to reveal it) or go to the appropriate tab of the Inspector for a complete list of all available parameters.
Move the playhead, change a parameter value, and repeat as needed. Easy and intuitive. You can even change parameter values while the project is playing, and your changes will be recorded in real time - this method is called "on the fly" recording.
A few things to watch out for when using Record Animation: first, remember to turn off recording so you don't accidentally create keyframes where you don't want any! Click the Record button or press A again to turn it off (it glows red when it's active). If you find that you are accidentally leaving it on, you can tell Motion to ignore it during playback by selecting Recording Options under the Mark menu, and checking the "Don't record keyframes during playback" checkbox.
Second, it's important to understand that when you turn on Record Animation, a keyframe is automatically set at the first frame of the selected object.
For example, if you turn on Record Animation, move the playhead to 5 seconds into the duration of an object, and set a Scale keyframe for 150%, then the object will grow from the previous value to 150% over the first 5 seconds that it's visible. Sometimes, this is not the behavior you want. Maybe you want the object to remain at 100% for the first 3 seconds, then grow to 150% between 3 seconds and 5 seconds. To acheive this, you could "trick" the Record Animation feature to set a keyframe at the 3 second mark by changing the scale value to any new value and then back to 100%, but in cases like this, I prefer to set keyframes the old-fashioned way: manually.
Creating Keyframes Manually
Although Record Animation is the fastest way to set keyframes, for the most control you'll want to set keyframes manually. To do this, you use the Animation Menu - an easily ignored little dash next to each keyframeable parameter in each tab of the Inspector (It's also available in the Keyframe Editor, but we'll get to that a little later).
Simply select your object or effect, position the playhead at the location for the keyframe, then select Add Keyframe from the Animation Menu.
Once you set a keyframe, the dash changes to a solid diamond. If the playhead is not parked directly on a keyframe, the diamond becomes hollow.
After setting your first keyframe, just repeat the process. But here's the quirk: you must add the keyframe before you set the new value for that keyframe. If you change the value before you add the keyframe, you are changing the value at all points in time. This process is different from both Final Cut Pro and After Effects, and if you are used to setting keyframes in those applications, it's sure to trip you up. So remember: add the keyframe first, then set the new value.
The Animation menu in the Inspector is also useful for jumping from one keyframe to the next, for disabling the animation (which retains the keyframes but just ignores them), or for resetting the parameter (which deletes all the keyframes and restores the parameter to its default value). But if you want to get deep into tweaking keyframes, the Keyframe Editor is the place to do it.
Oh, you may be wondering - what are the keyboard shortcuts for adding a keyframe? Or for moving from one keyframe to another? That brings us to another quirk of Motion: no keyboard shortcuts for adding or moving between keyframes. As opposed to After Effects (e.g., option-p to set a position keyframe) or Final Cut Pro (control-K sets a keyframe for most of the Motion tab parameters), you must click and drag in the Animation menu every time you want to set a keyframe or jump to a keyframe. So try to remember to use Record Animation whenever possible because it's just plain faster.
Manipulating Keyframes with the Keyframe Editor
Once you have set a few keyframes, you usually need to make adjustments: move the keyframe in time, align it to another keyframe, change its value, add or delete keyframes, or change how Motion animates, or interpolates, between keyframes. For all this detail work, head over to the Keyframe Editor in the Timing pane. If you select your keyframed object, by default you will be presented with just those parameters that you have animated. Clicking the "Fit visible curves into window" button at the bottom left will quickly resize your keyframes and curves quite nicely, although I like to drag the zoom slider in so that the end keyframes aren't pressed up against the edge of the window.
One way to work with individual keyframes in the Keyframe Editor is to click directly on them. Sliding up and down changes the keyframe value; sliding left or right changes the keyframe's location in time. To avoid changing both the location and the value of the keyframe at the same time, hold down the Shift key to constrain the motion to just vertically or just horizontally.
If you have a precise location in mind for your keyframe, like the current playhead location or another keyframe, turn on snapping by clicking the tiny button in the very bottom left corner. Note that this snapping is different than the Snap feature under the View menu, which turns on snapping in the Canvas.
If you want a precise value for a keyframe, you are better off entering it directly in the Inspector rather than trying to drag the keyframe up and down.
If you want to move multiple keyframes that are applied to an object all at the same frame to a different frame, it's easier to use the Timeline instead of the Keyframe Editor - all keyframes at a given frame are represented by just one keyframe icon - drag it left or right to move them all.
To add a keyframe directly in the Keyframe Editor, either double-click or option-click on a curve. I prefer option-clicking because the cursor changes into a crosshair to confirm that your mouse is directly over the curve.
To delete a keyframe, select it and hit the delete key. You can drag a marquee to select multiple keyframes.
The Keyframe Editor has its own Animation menu, similar to the one found in the the various tabs of the Inspector, so you can use it to set and move between keyframes. But it contains several other options as well, including the ability to choose the interpolation method.
Changing Keyframe Interpolation
Motion offers six different types of keyframe interpolation - that is, determining how the animation changes over time as it approaches and leaves each keyframe. To change the interpolation method for all keyframes, use the animation menu.
To change the interpolation for specific keyframe(s), select them, control-click, and choose the method.
The quirk here is that Motion considers the interpolation to be applied to the curve between the keyframes, which is technically accurate, but different from how other applications behave. For example, if you click on a keyframe and choose Ease In, you would expect the animation to slow down as it approaches the selected keyframe. But no! Instead, it's the next keyframe that gets affected. When you select a keyframe and change its interpolation, you are affecting to curve between the selected keyframe and the next keyframe in time. Once you get the concept, it will become second-hand nature.
Another quirk: depending on the type of parameter, Motion applies a different default keyframe interpolation. For example, if you set keyframes to animate the Scale of an object (using either Record Animation or Add Keyframe), the default interpolation is linear - the object has an instantaneous acceleration and deceleration at the keyframes. However, keyframes for Position are interpolated by default as Bezier - the object speeds up as it leaves one keyframe, and slows down as it approaches the next.
If you happen to be keyframing both position and scale at the same frames, for example panning across and zooming in on photograph, the mismatch in default interpolations will result in a less than ideal animation as the move starts and stops. The fix is to change the interpolation for the Scale parameter to Bezier as well - which brings us to our last quirk: separate x and y keyframes.
Parameters that have spatial components - such as postion, scale, and anchor point - have two keyframes: one for the horizontal value, and one for the vertical value. After Effects and Final Cut Pro both bundle (x,y) coordinate parameters into one keyframe. It's not a problem, it's just a difference you need to be aware of and it can make for some extra work - when changing keyframe interpolation for Position, for example, you need to change it for both the x and y parameters. Sometimes it can be difficult to select one of the values because the curves may lay directly on top of each other - in these cases, click the visibility checkbox to turn off the one that's in the way.
Summary
While behaviors are incredibly powerful and a lot of fun, the fact is that when you need to set precise, specific values for an animation, keyframes are they way to go. Motion has a powerful keyframe toolkit, and once you understand the differences between how Motion works with keyframes and other programs you may be used to, you can begin to work faster and with greater confidence. There's much more to keyframing in Motion that we didn't cover here, and there are more quirks along the way - we'll cover some more territory in Part 2. In the meantime, feel free to send Apple feedback as you get deeper into this surprisingly powerful application.
Copyright © 2005 Day Street Productions, Inc.
Mark Spencer is a freelance producer/editor, Apple-certified instructor for Final Cut Pro, Final Cut Pro Advanced, and Motion, and the author of the Motion Visual Quickstart Guide from Peachpit Press.
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