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548Final Cut Pro User Guide
Smooth out a slow-motion clip with video quality presets
To smooth out the apparent motion of a clip playing back in slow motion, you can apply
frame blending or optical flow analysis to the retimed clip.
Note:
Final Cut Pro 10.2 or later uses an advanced optical flow algorithm that can
accommodate a wide range of source footage. Any new projects created with Final Cut Pro
10.2 or later will benefit from these improvements (if they include an optical flow video
quality setting). If you have projects created in earlier versions of Final Cut Pro that have
optical flow settings, you can reanalyze them for improved quality by choosing Optical Flow
in step 2 below.
1. In the Final Cut Pro timeline, select a range, a whole clip, or a group of clips set to play
in slow motion.
2. Click the Retime pop-up menu below the viewer and choose Video Quality, then choose
a setting from the submenu.
• Normal: The default setting. Frames are duplicated, and no frame blending is applied
to the slow-motion clip. No rendering is required.
• Frame Blending: Adds in-between frames by blending individual pixels of
neighboring frames. Slow-motion clips created with Frame Blending appear to
play back more smoothly than those created with the Normal (duplication) setting.
Rendering is required.
• Optical Flow: Adds in-between frames using an optical flow algorithm, which
analyzes the clip to determine the directional movement of pixels and then draws
portions of the new frames based on the optical flow analysis. Rendering is required.
Only the portion of the clip used in the project (the media between the clip start and
end points) is analyzed.
Tip: Before using Optical Flow, try using Frame Blending and experiment with various
slow-motion settings until you’re satisfied with the speed. Then, if you see artifacts or
want the very best image quality, try using Optical Flow.
Create variable speed effects in Final Cut Pro
In addition to constant speed changes, you can create variable speed effects in which
the playback speed of a clip changes dynamically. For example, a clip might start in slow
motion, speed up to fast motion, and then slow back down to regular speed. You create
variable speed changes by identifying ranges of a clip as speed segments—sections in a
clip that have different playback speeds. Each speed segment has its own constant speed
setting. You can set speed segments to any speed value, forward or backward, and you can
create abrupt shifts between speed segments, or gradual transitions (also called ramps).
Note: You can’t create smooth transitions between a speed segment set to a forward speed
and a speed segment set to reverse speed (and vice versa).