Apple Final Cut Express 4 - Manual (Page 1069)

Appendix A Video Formats 1069
XIII
About Field Dominance
Field dominance is an issue when recording and playing back interlaced video material.
With progressive video, there is only one way to play back a video frame: start at line 1
and scan until the end of the last line. With interlaced video, the video player must
know whether to scan the odd lines first, or the even lines. In other words, each time a
frame is displayed, which field should be displayed first, field 1 or 2? The field displayed
first is totally dependent on which field was captured by the camera and recorded first.
Each field is a snapshot in time, so if field 1 is recorded earlier in time than field 2, field 1
must be played back before field 2. If the wrong field order is chosen, each frame’s fields
play backward in time, even though each frame as a whole still moves forward. The effect
is a very noticeable stutter happening 60 (NTSC) or 50 (PAL) times a second.
Each piece of video equipment and each video format has a preferred field dominance.
This prevents you from, say, editing two field 2s back to back, and makes sure that each
field is played back in the right order.
Setting Field Dominance in Final Cut Express
In Final Cut Express, the field dominance of clips must match the sequence field
dominance. Otherwise, the fields stutter during playback because each pair of fields
plays back in the wrong order. For example, DV NTSC and DV PAL always have a field
dominance of Lower (Even). If you’re working in a sequence and you see that imported
clips are flickering, check to make sure the field dominance of those additional clips
matches the field dominance of your edited sequence.
Important: You need to change the Field Dominance setting of your projects and
sequences only if you change your video hardware setup.
In Final Cut Express, there are two options for field dominance:
 Upper (field 2 is dominant, so the second field is drawn first)
 Lower (field 1 is dominant, so the first field is drawn first)
Generally, Upper is used by 640 x 480 systems, while Lower is most common in
professional 720 x 486 and DV 720 x 480 systems.