The RT Retimer effect is located in the Titles Browser in Final Cut Pro X, in the Ripple Tools II category.
To apply the RT Retimer effect, drag it from the Titles Browser over the target clip or clips in your project.
If you want the effect to exactly match the duration of a single clip, then first make sure the playhead or skimmer is over the clip and press the X key to mark the clip range. Then, select the RT Retimer thumbnail in the Titles Browser and press the Q key to connect it to the clip range.
Once in the project you can drag on the title to reposition it or drag on either end to trim it. Now, select it, open the Inspector if necessary (Command-4), and select the Title Inspector.
Enable Show QuickTips for some basic information on how to use the effect. RT Retimer uses a different approach than the retiming functionality built into FCPX. With the built-in approach, when you speed a clip up or slow it down, it changes duration – and if you want to speed-ramp a clip (have it’s speed change over time so that it speeds up, slows down, freezes and/or reverses), there’s no easy way to accomplish that task. RT Retimer lets you retime video without changing the clip duration.
It works best on clips that were shot with a high frame rate so that at normal playback, they appear to play in slow motion. But it can be applied to any type of video clip. Of all the effects in the Ripple Tools II collection, this one takes the most time to understand how to work with it. But it’s not difficult. There are two different ways you can retime your video: either by offsetting from the Current Frame, or from the First Frame. You choose your method in the Offset from pop-up menu in the Inspector.
Method 1: Frame offset set to Current Frame. This the default method. The video plays normally until you set keyframes. Step 1: With the playhead on the first frame of the effect, set a keyframe for the Frame offset at 0.
Step 2: Move the playhead to a point in time to where you want to move a frame. In this example, I want to move the frame where the batter contacts the ball earlier in time, so I first move to the time where I want that frame to appear, at 3:16:02.
Step 3: Drag the Frame Offset slider or value field until the frame you want appears. So in the example, I drag until I see the frame where he contacts the ball.
The clip will now be retimed so that the target frame appears at the target time without changing the clip duration. In my example, the video will play faster up until he hits the ball, then will play slower for the rest of the clip – but the overall clip duration remains the same. If you select the RT Retimer effect and press Control-V (or choose Clip > Show Video Animation), you can see the keyframes.
Important: moving the keyframe with Method 1 changes the frame that plays on the keyframe – this is because, in this case, the frame at the keyframe is always 42 frames away from what was there originally. If you want to move the frame of the guy contacting the ball somewhere else, you would need to move it and then adjust the Frame offset value once again.
Method 2: Frame offset from set to First Frame. This method takes a few steps to set up, but then it works more intuitively (in my opinion of course). By default, the clip is frozen on the first frame, so with the first 2 steps you make it play normally.
Step 1: With the playhead on the first frame of the clip set a keyframe for the Frame Offset at 0. (Same as Method 1).
Step 2: Move the playhead to the end of the RT Retimer effect (down arrow, left arrow), then change the Frame Offset to one frame less than the number of frames in the clip. Now the clip will play normally.
NOTE: to determine the number of frames in the clip, choose Final Cut Pro > Preferences, and in the Editing pane, change the Time Display to Frames. Then close the Preferences window, select the video clip, and press Control-D. The Dashboard will show the number of frames in the clip. In my example, my clip has 655 frames.
The video will now play normally.
Step 3: Move the playhead to a frame you want to move. Set a keyframe, then press Control-V to open the Video Animation editor. Again, in this example, I want to move the frame where the batter contacts the ball. So this time, I move to that specific frame (not to where I want it to end up, as in Method 1).
Step 4: You can now move this frame anywhere else in the clip. If you move it earlier, the frames before will play faster and the frames after will play slower.
You can of course add as many keyframes as you like to speed up, reverse, or freeze the video, so have fun.
Note: Frame Blending and Optical Flow retiming (invoked when you change the Video Quality in the Retime menu) are not available for this effect due to how Final Cut Pro X handles title effects.