The major difference is that in constant speed time remapping, we have only two keyframes: one at the In Point and one at the Out Point of the clip. Both are "corner" keyframes, which means they are angles with no Bezier adjustment abilities. The whole clip moves at one "constant" speed—no changes, simple as that. Also, with constant speed changes, the duration of our clip in the Timeline window will change accordingly. With variable speed remapping, we can have many keyframes throughout the clip, and each can be a corner or a "smooth" keyframe. Smooth keyframes have Bezier Handles to control the Ease In/Ease Out function and the slope/shape of the curve around the keyframe point. Also, when we make speed changes, the clip in our Timeline window will not change duration, unlike it did with constant speed changes.
Working in the Viewer Window
To understand the mechanics of variable-speed remapping, let’s first go over making and changing keyframe points in the Viewer’s Time Remap graph. I suggest that if you want to begin experimenting with variable speed, use a long clip with lots of space before the In point and lots of space after the Out point (i.e., a clip with very long handles).
I’ll begin by opening a clip from the Timeline window into the Viewer window, going to the Motion tab, and opening the Time Remap section. I hit "P" to switch to my pen tool and click along the green line to make keyframe points. Then, I can right-click each point to change it. If it is a corner point, I’m given the choice of deleting the point or changing it to a smooth point. If it is already a smooth point, I’m given the choice of changing it to a corner point or deleting it (Figure 1, below).
I can also hit "A" to switch back to my default selection or use the arrow tool to grab these points and move them up and down or left and right. Or I can grab the Bezier handles and move them closer toward the points (shorten Ease In/Ease Out time), drag them farther from the point (lengthen Ease In/Ease Out time), or rotate them to create curves and shapes.
Now, that by itself is just dangerous information since it doesn’t really tell you how to use it. You need to know how you can manipulate these points in the Viewer’s Time Remap graph. And just like last time, a line going at 45 degrees from lower left to top right (relatively speaking) is normal 100% speed. The flatter the line is, the closer the clip is to being a still image; the steeper the line is, the faster you’re speeding the clip up. A slant going from any upper-left point to a lower-right point is going backward in time.
So let’s look at Figure 1 (above) again, and I’ll walk you through this graph. It is important to understand the graph—to be able to simply look at it and know right away what is happening—as this graph is the best tool you have for doing variable speed remapping. There are other tools that are helpful. But to me, this one is the most important to understand.
Beginning with the first of six keyframe points in this graph, which sits on our clip’s In point, we see a Bezier handle on it, so we know that first keyframe is a smooth point. And I can see clearly that our movement in this clip will begin in slow motion due to the shallow slope of the green line. As the timeline playhead plays forward, it will approach the curve, speeding up to very fast motion playback as it does, indicated by the very steep curve in the line at the end of that segment. Then, just before the second keyframe point (corner), it suddenly slows down until it hits that second point. The line from the second point to the third point (corner) is flat, which means that we’ll be looking at a still image of whatever frame that second keyframe point was on. Then when we hit our third point (corner), moving forward to the fourth point, we see a nice 45-degree straight line, which tells me the clip will be playing forward at normal speed to the fourth point (corner). As we pass the fourth point and head up to the fifth keyframe corner point (smooth), we’ll be playing normal speed at first, but about halfway between the points, we will begin to taper off, playing slower and slower until we hit an almost still frame at the fifth point.
Following the curve from there, we will actually begin to play backward in slow motion (downward, shallow slope), going faster until we get to what seems to be a 100% speed playback in reverse. As we reach the trough of this curve, we will gradually slow down into slow motion until we ease into a still frame. We then ease out of it playing in forward slow motion, gradually increasing speed until we play at normal 100% forward motion. Finally, we hit the sixth (smooth) point, which is at our clip’s Out point.
Working in the Timeline Window
In the Timeline window, there are a couple of neat tools that will help you. The first thing we have to do here is turn on Clip Keyframes. This button is in the lower-left corner of the Timeline window, and it looks like two parallel lines, the top one being shorter than the other (Figure 2). When this is turned on, a large space opens up below the video and audio tracks. This space is where you can look at keyframe points and move them around. It also reveals a timing marker track. The timing marker track has vertical lines in it showing the timing of the clip. Evenly spaced lines represent normal 100% forward speed. The closer together the marks are, the faster the clip plays; the farther apart they are, the slower the clip plays.
As shown in Figure 2 (below), a section of our video track’s timing markers toward the end are red. Red markers show reverse playback. This is simply a visual reference that some folks find handy when working with time remapping.The first interactive tool to learn to use at this point is how to resize this keyframe work area below your clip. It’s hard to see, but if you look closely to the very beginning of the track, there’s a small space running up and down the height of the track. In Figure 2 (below), it’s dark gray. It turns dark gray like this when you’re adjusting it. It adjusts the height of the keyframe work area.
When you place your mouse over the bottom left corner of your video clip, you will see one of two double-arrow cursors appear. One is a double-sided arrow pointing left and right. You use this one to trim your video clip—we don’t want that one. We want the one that points up and down. If you see the one pointing left and right, move your mouse just a hair to the left, and it will turn into the up-and-down double-arrow cursor. Click and drag to resize the height of the keyframe work area below the actual clip on that track. The bar will turn dark gray. If you hold the cursor there for a couple of seconds, the tool tip will pop up and "Keyframe Editor Size" will be displayed.
Once you’ve made your keyframe work space taller, the next thing to do is to decide what parameter’s keyframes you want to work with. Mouse over a blank area in the keyframe work area, right-click (or control-click if you’re saddled with a single-button mouse), and a menu will pop up showing all the different areas available in the Viewer’s Motion tab. Go to the bottom for Time Remap and from the secondary menu choose Time Graph.
Again, refer to Figure 2 (above) to see what this should look like. You’ll see a blue line running toward the top of the keyframe workspace. This is the same line in the Time Remap section of the Motion tab in the Viewer window. The points on it are specific frames on your clip that are marked as keyframes. You can pull them left and right, up and down, just as in the Viewer graph. The key concept to remember here is that keyframe is a single frame in your clip that has been uniquely marked as a keyframe. Moving the keyframe point in either of the graphs moves that specific frame in your clip.
Thus, moving a keyframe point to the right bunches up everything to the right, making the frames play faster. And everything to the left of that keyframe gets pulled farther apart, thus causing the frames to play slower.
Therefore, in the keyframe workspace below your clip, you can use your normal arrow cursor to drag those keyframe points left and right. It’s that simple. They don’t go up and down as in the graph in the Viewer.
Using the Viewer Graph and the Timeline Window Graph Together
Figure 3 (below) shows both the Viewer window’s graph and the Timeline window’s graph. The top one is the Viewer window graph, and the bottom one is the Timeline window. Study these closely. You’ll see how they work together, and why I encourage folks to have both open at the same time, using both to do variable-speed remapping. Notice in the area where the Viewer’s graph slopes downward, the speed indicator track in the Timeline shows red marks. Where the Viewer’s graph shows slower speed, the Timeline’s track shows frame marks spaced farther apart. Where the Timeline’s track shows frame marks spaced close together, the Viewer’s graph shows a steep fast motion angle. Notice how all the keyframe points line up together?
You can also hit "P" to get your pen tool in the Timeline window to point and click on the keyframe line to create new keyframe points. Then hit "A" to get back to your normal arrow cursor and drag the points back and forth. In the Timeline window you can’t change from smooth to corner or delete points, and you’ll see your work reflected in the Viewer’s Time Remap graph. But using the two together makes variable-speed time remapping much more controllable and useful.
Using the Time Remap Tool
There is one last tool I’ll mention, even though it’s not my favorite. Some folks like it, but I’ve never been comfortable with it; it all comes down to personal style and taste. I’m referring to the Time Remap Tool, which is found in the Tool palette in the lower right of your standard FCP window setup (Figure 4, below). It’s in the Slip and Slide tools group.
With this tool, you can click directly on your clip in the Timeline and drag left and right. It works just like moving keyframes in the keyframe workspace below the clip, but it offers a visual reference similar to the Slip and Slide tools (Figure 5, below). When you first click on it, it creates a new keyframe point, and as you drag left and right, it shows adjustments made between it and the keyframes to its left and right. It does not affect other existing keyframes. A tool tip pops up showing you the speed of the clip to the left of this keyframe and to the right. If it’s a constant speed remap, it’ll show the percentage. If it’s variable speed, it just reads "Variable."
It also shows a brown overlay on the clip itself, so you know how much room you have to play with. But due to the nature of speed work, I don’t find it very useful or understandable.
But try it, play with it; you may or may not like it. Just be sure to have the graph in the Viewer open at the same time to see the details of what it’s doing.
Ben Balser (benb at bbalser.com) is an Apple Certified Trainer based in New Orleans, Louisiana. He specializes in training and consulting, and he also produces documentaries, educational material, and commercial work. Contact Ben with Final Cut Studio questions and he will try to address them in future tutorials.