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, PAL, or interlaced HD monitor). 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 Pro couldn’t determine which field dominance to set when the clip was imported. You can also 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 Pro 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 Pro automatically adds a Shift Fields filter to the clip so that the clip field dominance matches the field dominance of the sequence.

Clip field dominance
Sequence field dominance
Shift direction of Shift Fields filter
Lower (Even)
Upper (Odd)
–1
Upper (Odd)
Lower (Even)
+1

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.

Mixing Interlaced and Progressive Footage

The scanning method of a clip or sequence is determined by its field dominance setting. There are three possible field dominance settings that determine clip and sequence scanning methods.

Scanning method
Field dominance setting
Progressive
None
Interlaced
Upper (Odd) Lower (Even)

Interlaced clips added to a progressive sequence are deinterlaced during playback. Progressive clips added to an interlaced sequence are interlaced during export or output.

Note: Computer displays are inherently progressive, so you should always connect an external video monitor when testing interlaced video issues.

For the highest quality, you can use Compressor to deinterlace interlaced footage before editing it into a progressive sequence. For details, see the Compressor User Manual, available in Compressor Help.