Apple Final Cut Pro 7 - Manual (Page 1315)

• All Lines Except Top & Bottom: Displays every line except the top nine and bottom nine
lines, which are reserved for signals such as closed captioning. The word “most” appears
in the lower-right corner of the Video Scopes tab.
• Limited Lines (Fastest): This mode is always used during real-time playback. Accuracy
is limited to 32 lines that are evenly distributed from the top to the bottom of the action
safe area of standard definition video. This is sufficient to catch video elements whose
height equals 5 to 10 percent of the total size of your image.
Important: The accuracy level you choose here affects video scopes when the playhead
is paused or scrubbing; real-time video scope updating always uses the Limited Lines
(Fastest) option.
The lower-right corner of the Video Scopes tab indicates the scope display option selected
in the RT pop-up menu.
Video Scope Restrictions and Performance
The following list describes limitations when using the Video Scopes Playback option in
Final Cut Pro:
• You must be using a format that Final Cut Pro can process in real time. For a list of
formats that Final Cut Pro can process in real time, choose Final Cut Pro > System
Settings, then click Effect Handling.
• The View pop-up menu in the Video Scopes tab must be set to Current Frame (referring
to the Canvas) or Viewer. Options such as Current Frame w/o Filters and Previous Edit
turn off the Video Scopes Playback option.
When checking video scope accuracy, you can analyze all video lines only when playback
is stopped or when scrubbing. The Video Scopes Playback option updates the Video
Scopes tab using the Limited Lines (Fastest) option. For more information, see
“Using
Video Scopes in Real Time.”
Preventing Illegal Broadcast Levels
Broadcast facilities have limits on the maximum values of luma and chroma that are
allowable for broadcast. If a video exceeds these limits, distortion can appear in the form
of colors bleeding into one another, the whites and blacks of your program washing out,
or the picture signal bleeding into the audio signal and causing audible distortion. In all
these cases, exceeding standard signal levels can result in unacceptable transmission
quality.
1315 Chapter 78 Measuring and Setting Video Levels