Apple Final Cut Pro 6 - Manual (Page 1203)

418 Part II Effects
Temporarily Excluding Clips from Playback or Output
In the process of fine-tuning effects in a sequence or experimenting with multilayer effects
in sequences, it can be helpful to compare how the sequence plays with and without
certain clips. In Final Cut Pro, you can exclude (rather than delete) a clip from playback.
Temporarily excluding a clip from playback and output is called disabling the clip. By
temporarily disabling specific clips, you can focus on one clip to the exclusion of clips
above or below it, or you can see how another clip would work in place of the original
without removing it.
It’s helpful to disable a clip rather than deleting it, in case you change your mind and
want to use it again later. Or, you may want to disable just the video or audio portion of
a clip, so that you can keep the video or audio available without including it in
playback or output. This is somewhat like muting channels in an audio mixer, except
that you exclude playback of clips instead of entire tracks.
Superimposing Video When Preparing for EDL Export
In an Edit Decision List (EDL), a Super or Key track is the equivalent of a single
superimposed video track in Final Cut Pro. EDLs can recognize only one Key track, so
V2 is the only video track other than V1 that appears in an exported EDL. Transitions
in track V2 are not allowed in EDLs and are ignored. If you want to use a transition in
track V2, use keyframes in the opacity overlay to dissolve V2 up and down. (See
Volume IV, Chapter 10, “Importing and Exporting EDLs.”)
The opacity overlay in the Timeline appears as the “Key Level” in your exported EDL.
Opacity keyframes, if they exist, are translated into values for the Key Level and are
calculated in the EDL in relation to the timecode of the master tape. These numbers
are for use by a video switcher. Some online systems can translate these for
automatic use by some switchers, but more commonly they are used only as notes
for the editor to use in an online session. These values and their locations appear as
notes in the EDL.