In addition to using the trim tools, entering a numeric trim value, and working with shortcut keys, you can also trim dynamically, or on the fly, in the Trim Edit window using the J-K-L keys. This “live play trimming” in Final Cut Pro is called dynamic trimming.
When dynamic trimming is enabled, the J-K-L keys behave exactly as they do in the Avid trim mode. You can use J or L to play and shuttle forward and back, and press K to execute the trim. Also common to both applications, if you hold down K and J or L to shuttle in slow motion, simply releasing the buttons will execute the trim. Unlike the process in Avid, however, when dynamic trimming is enabled in FCP, pressing the spacebar will simply pause the playhead without performing a trim or playing around the edit. This allows you to search again for the trim point before pressing K.
To trim using the J-K-L keys:
- In the Timeline, double-click the edit point you want to edit.
- Select the Dynamic check box.
- Move the pointer over either the A-side or B-side clip. If you’re using the Roll tool, you do not have to click or select the image. FCP responds to the location of the cursor. If you want to dynamically trim just one side of the edit, click to choose it prior to pressing J or L.
- Press J or L to play the clip backward or forward.
- As the clip is playing, press K where you want the new edit point to be.