Advanced Video Camera and Editing


 
Keyframing

Keyframing changes the parameters of a clip over the course of time. It takes no less than 2 keyframes to do a simple animation. 

The first keyframe is inserted at a certain position in the clip, such as the beginning. The second keyframe is added later in the clip, perhaps at the end. The keyframe parameters can be changed so that the clip does one thing at the beginning and something else at the end.   

These parameters can be anything from changing a video clip’s opacity over time, to changing the levels of audio. You can also keyframe filter parameters and motion.

Final Cut Pro generates keyframe graphs in the Viewer's filter, motion, and audio tabs. It’s also possible to see video opacity and audio levels in the Timeline. Lastly you can display keyframes in the Canvas. 


Keyframing in the Canvas

Keyframes are quite easy to graph in the Canvas. For example, say you want to animate a cannon ball that has been launched into Earth’s orbit (one of Sir Isaac Newton’s thought experiments involved a very powerful cannon shooting a projectile into orbit).

First make sure that the Image+Wireframe is activated in the Canvas. This will make it easier to "grab" the object with the mouse pointer and move it across the frame.

Choose View > Image+Wireframe.

Next, maximise the Canvas window to make it easier to view the keyframes once you start adding them.

Set the zoom controls at the top of the Canvas to 50%.


We want to move the image of the cannon ball left to right across the frame so that it appears to be arcing against the Earth’s curve. We also want the cannon ball to start off looking very small in the distance and then get larger as it approaches the viewer. Eventually, the cannon ball will move past the edge of the frame.

  • Insert the clip of the Earth in the V1 track of the Timeline. 
  • Now, insert the cannon ball image in the V2 track. The image as it appears in the Canvas is the cannon ball over Earth.

As you can see the size of the cannon ball will be made smaller. But first, let's apply the keyframes, starting at the end of the cannon ball's path. The reason we establish the end position first is because the viewer will see this composition for the duration of the scene. In contrast, the beginning happens in a matter of a second or two. 

  • In the Timeline, position the playhead at the point where the cannon ball's path will end.
  • Select the cannon ball clip (double-click it). The wireframe for the clip shows up in the Canvas.
  • Use the pointer and grab the cannon ball image, dragging it to the right corner, just past the frame. 
  • Once you've positioned the image, click the Add Motion Keyframe button, located in the lower right of the Canvas (the keyframe icon is a diamond-shape).                         
  • This particular button selects only the motion parameters. Once you click it, the wireframe in the Canvas turns green, which indicates that the playhead is on the keyframe. 

Press the Up Arrow key to move the playhead to the beginning of the cannon ball clip. This is where you can add the second keyframe, which is actually at the beginning of the motion. Drag the cannon ball image to the starting position, perhaps on the edge of Earth's horizon. Again, click the Add Motion Keyframe button, which will add a keyframe at this point.


You can now see clearly the path of the cannon ball as indicated by the dotted line between the two keyframes. The spacing between the dots shows how fast or slow the object will move. In other words, the closer the dots, the slower the motion.

Now we should change the size of the cannon ball. Since we used the Add Motion Keyframes button, we'll be able to change not just the position of the cannon ball, but also its size as it moves across the frame. 

In the Viewer, select the Motion tab. Each motion parameter has its own keyframe button to the right. The button resembles a diamond shape. If the playhead is parked on a keyframe, you will see that the corresponding keyframe button is coloured green.


You can toggle between keyframes using the Previous Keyframe and Next Keyframe buttons that are on either side of the Add Keyframe button. These buttons dim when there are no more keyframes in that direction.

To the right of the keyframe buttons there is an overview bar showing the keyframe graph for that motion parameter.

In the Size parameter, toggle to the first keyframe and set the value to 0, which will shrink the cannon ball to a singularity. Then toggle to the next keyframe and change the size of the cannon ball to something that might make logical sense depending on how close you want to the cannon ball to get (in this example, 80 units). 

Play the sequence to see your animated effect.

NOTE: You may need to render the clip (Option-R) to play it at full frame rate.

Modifying the Path

The above example shows the cannon ball is moving on a straight path.

However, we want the motion to appear curved.Using the mouse pointer, click the middle of the path. The pointer adds a new keyframe. Grab the new keyframe and drag it to the right. This new path automatically curves. 


Click Undo and this time, park the playhead on the middle keyframe. The cannon ball is now visible at that position. Drag the cannon ball to the right. The path no longer curves, but instead defaults as a corner.


Fortunately, this corner can be smoothed out into a curve with the greatest of ease. 

  • Make sure the cannon ball clip is selected (double-click it).

  • Position the playhead on the middle keyframe.

  • In the Canvas, Control-click the middle keyframe and choose Linear from the shortcut menu.

The path is now curved. Use the Bezier handles to adjust the shape of the curve. It might become necessary to zoom in a bit on the Canvas to see what you're doing.

 

 Bezier handles

Perhaps you’re satisfied with the path, but would like to re-position it in the frame. Rather than move each individual keyframe, there’s a way to move everything all at once.

  • Press the Up Arrow key to make sure the playhead is at the In point of the clip
  • Shift-Command and drag the path to its new position.


Controlling Acceleration

You can control how fast or slow the object moves from one keyframe to the next.

  • Control-click the first keyframe
  • In the shortcut menu, select Ease In/Ease Out
  • Control-click the second or last keyframe and choose Ease In/Ease Out