Apple Final Cut Pro 5 - Manual (Page 1298)

Chapter 23 Using RT Extreme 511
III
About Dynamic Real-Time Playback
To maximize performance during playback, you can choose to have Final Cut Pro
automatically adjust the video quality, frame rate, or both, during playback. This is
called dynamic real-time playback.
Dynamic real-time playback continually adjusts video quality and frame rate on a
frame-by-frame basis. When there are fewer demands on the CPU, Final Cut Pro uses
higher video quality or a higher frame rate. When the Timeline reaches a clip with more
effects, Final Cut Pro reduces the video quality or the frame rate, which reduces the
processing requirements of the clip. Since Final Cut Pro automatically adjusts the
playback quality as necessary, you always get the highest quality playback possible
without having to stop your sequence to make quality adjustments.
Playback video quality and frame rate can be controlled independently. For example, if
you need to see every frame during playback, you can set your sequence playback
frame rate to Full and video quality to Dynamic. In this case, your sequence video
quality may be reduced during playback, but every frame will play. On the other hand,
if you are doing detailed compositing work that depends on high quality video display,
you can set your sequence playback video quality to High and your sequence frame
rate to Dynamic.
If neither frame rate nor video quality is critical (for example, if you are editing a multiclip
sequence), you can choose Dynamic for both playback video quality and frame rate.