Advanced Green-screen Editing

Advanced Green-screen Editing

In the September issue, we showed you how to build a green screen, then use chroma-keying to trim the subject out of a green-backed video clip to place that subject on a different background clip (Make (and Use) Your Own Green Screen). This month we’ll show you how to get a handle on synchronizing everything between two clips visually and along the timeline, plus color-keying tricks to help you make fun, easy work out of green-screen compositing.



> Final Cut Express ($299) or Final Cut Pro (as part of Final Cut Studio, $1,299)



The Interface (as shown above)

1. Browser. Your imported video clips and Final Cut Sequences live here under Project tabs; the Effects tab contains all of Final Cut’s audio and video filters and transitions. Use the icons to change from list to thumbnail view for easy clip identification.


2. Viewer. Double-click a clip to load it into the Viewer and select the Filters tab to access the configurators for that clip’s filters; click the Motion tab to move or resize clips in the frame.


3. Canvas. Preview your composition here, using the Scrubber to scrub or the control buttons to navigate through the frames.


4. Timeline. Drag clips here to get started. The bottom track (V1) is the background, and you can stack as many as 98 more tracks sequentially above it. Final Cut automatically rips the clips’ audio tracks to the Timeline’s lower section.

5. Toolbar. More for celluloid-style film editing, the tools won’t do anything to clips in the Viewer window until you select View > Image + Wireframe to activate Wireframe mode.


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1. Set the Stage

Launch Final Cut and use the default new project that opens with the app, or select File > New Project. Import all of your footage for the project by dragging files into Final Cut’s Browser, and then save your project (if you don’t save it at this point, Final Cut will prompt you that it can’t perform its auto-save magic until you do). Drag the background clip into the Timeline’s V1 track and drag the foreground clip into V2.


You can jump right into the effects now, but eventually you’ll want to reposition the start and end points of the clips or edit them for length (hint: use the Razor Blade tool). Click and drag to move the clips along the Timeline, and for precise placement, highlight the clip and press Option and the left or right arrow key to move one frame at a time. When trimming clips for length, just activate the Razor Blade and click on the clip in the Timeline; highlight the scraps and press Delete to remove them. To manipulate the video in the frame, select View > Image + Wireframe and use the Selection and Crop tools to manipulate the image in the Viewer window.


Press Option-left Option-right arrow to nudge a clip along the timeline; View > Image + Wireframe puts adjustment handles on your clips.






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