Apple Final Cut Express 4 - Manual (Page 926)

926 Part X Real Time and Rendering
Combining Interlaced Footage with Different Field Dominances
Field dominance determines the order in which fields are scanned on an interlaced
monitor (such as an NTSC or PAL). If a format uses Upper (Odd) field dominance, the
first field scanned (called field 1) is made up of the odd lines in the video frame. Lower
(Even) field dominance scans the even lines first.
Note: A clip’s Field Dominance property can also be Not Set, which means that the
clip’s media file is likely interlaced but Final Cut Express couldn’t determine which field
dominance to set when the clip was imported. You can manually change the field
dominance of a clip in the Browser or the Item Properties window, but you should
usually do this only if the clip’s Field Dominance property is Not Set.
If the field dominance is set incorrectly for a clip, the fields of each frame are played in
reverse order, producing a rapid stutter in which the overall video motion is forward,
but the fields of each frame are played backward.
Using the Shift Fields Filter
When you add a clip to a sequence, Final Cut Express checks the field dominance
settings of both to see if they match. If both the clip and sequence are interlaced but
use opposite field dominance, Final Cut Express automatically adds a Shift Fields filter to
the clip so that the clip field dominance matches the field dominance of the sequence.
In most cases, the Shift Fields filter is applied automatically, so you rarely need to apply
this filter yourself. However, you can modify, add, or delete the Shift Fields filter just as
you can any other filter. The Shift Fields filter is located in the Effects tab and Effects
menu within the video filters Video category.
Clip field
dominance Sequence field
dominance Shift direction
of Shift Fields filter
Lower (Even) Upper (Odd) –1
Upper (Odd) Lower (Even) +1