Apple Final Cut Pro 6 - Manual (Page 1403)

618 Part IV Real Time and Rendering
For basic editing tasks, Final Cut Pro handles real-time processing automatically,
keeping you focused on the creative choices at hand. However, if you work with a lot of
effects or if you color correct video footage, you should take some time to learn the
details about the real-time architecture of Final Cut Pro.
How Real-Time Processing Works
Consider a clip placed in a sequence. Even when no effects are applied to the clip,
Final Cut Pro and your computer must do a certain amount of work to play back the media
file associated with that clip: the hard drive must be able to read the frames of video as
fast as they need to be displayed, and the computer processor must decode each video
frame into uncompressed pixels that are then shown on your computer display.
In the past, even the most expensive computers could barely achieve the required hard
disk and processor speeds. Editors often had to install specialized video cards that
could provide the necessary processing power for playback. Today, personal computers
can easily achieve video playback and still have a lot of processing power left to spare.
How Final Cut Pro Calculates Processor Workload
You can process your video footage in a remarkable number of ways: by adding video
filters, adding motion effects such as scaling and rotation, making speed changes, adding
transitions between clips, and compositing multiple video layers. All of these effects are
really just mathematical operations performed on the pixels of your video. The more
effects you add to a clip, the more operations are required to display the results.
Real-Time Playback Versus Rendering
For most stages of editing, reduced playback quality is more acceptable than losing
the ability to play back effects in real time. Toward the end of a project, during the
“finishing” stages such as color correction and output, you can choose to render at
full quality to ensure the best results. For more information, see Chapter 29,
“
Rendering and Video Processing Settings ,” on page 645.
Note: Final Cut Pro always displays real-time previews using 8-bit processing.