Apple Final Cut Pro 5 - Manual (Page 1311)

524 Part III Output
 Unlimited RT: Selecting this option tells Final Cut Pro to play as many frames as
possible when your effects exceed the processing power of your computer.
Final Cut Pro does this by spending time to process some frames in real time while
skipping others completely. Unrestricted real-time playback allows you to play
more effects, but increases the likelihood that your sequence will drop frames
during playback. This mode is useful for getting a real-time preview of complex
effects compositions. Embedded projects such as Motion and LiveType can also be
played back in this mode.
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Tip: Turning on Unlimited RT is the only way to enable third-party FXScript filters and
transitions to play in real time, if they’re capable of doing so.
 Play Base Layer Only (if render needed): If this option is selected, Final Cut Pro ignores
effects processing altogether in areas of your sequence where the applied video
effects require rendering for playback (indicated by a red render bar). Motion effects
or video filters are ignored and the clip’s original media file is shown without any
processing. If you have multiple tracks of composited video, only the video clip item
on the lowest-numbered visible video track plays back—all other layered video items
are ignored.
This option also affects audio playback. When playing over an unrendered portion of
a sequence, no effects are played back. The number of audio tracks that play
depends on whether or not you have selected the Play Base Layer Only option.
 If selected: The first two tracks of audio play back.
 If unselected: The number of audio tracks that play back is determined by the
number of real-time audio tracks you have set in the General tab of the User
Preferences window.
 Beep When Playing Unrendered Audio: This option is only available in the Playback
Control tab of the System Settings window. When this option is enabled, audio clip
items that require rendering are played back as audible beeps. This is the audio
equivalent to the “Unrendered” screen you see when your video requires rendering.
If the Play Base Layer Only option is enabled, the beeps are not heard.
 Scrub High Quality: When this option is enabled, video displayed in the Canvas is
shown at full quality when you scrub or when the video is stopped. If you deselect
this option, the video quality during scrubbing is determined by the current Playback
Video Quality setting. Deselecting this option allows you to improve responsiveness
during scrubbing, especially when using CPU-intensive codecs such as HDV, or
options such as multiclip playback.