2017

consecutively at slightly different moments. The field recorded first is called the dominant field. For example,
when recording NTSC using Field 1 as the dominant field, Field 2 is recorded a 1/60th of a second after Field
1. When the interlaced video is played, the two fields of each frame are then displayed with a temporal
offset, causing the human eye to perceive a smooth, continuous moving image.
Because of this time difference however, interlaced video can sometimes display jagged horizontal edges,
particularly when showing subjects in fast motion. In addition, not all such video formats interlace frames
in the same way. When different interlaced formats are mixed, the field dominance of the clips must be
changed to avoid visual artifacts and jitter. In Smoke, use the video field management tools to do so.
By default when editing or compositing clips that have conflicting scan formats, Smoke displays warning
messages and requires confirmation of potentially problematic operations. These warnings can be disabled
if desired by enabling Ignore Scan Format in the Clip Select section of the
General Preferences (page 1396).
About Field Dominance
Most interlaced video formats are Field 1 dominant, with a few exceptions. This means that for a given
frame, Field 1 is recorded earlier in time, and therefore should be displayed first during broadcast. Field 2 is
recorded after Field 1 and is displayed second.
Interlaced video formats may also differ in the first active line. The first active line is the uppermost line in
the frame. In some interlaced video formats, this uppermost line belongs to Field 1, while in others it belongs
to Field 2.
Other applications:Displayed in FCP
as:
Displayed in Avid
as:
Displayed in Smoke as:First active line be-
longs to:
Format:
f2
bottom
LowerEvenField 2NTSC
■ F1 if matching project's
field dominance
■ F2 if not matching pro-
ject's field dominance
f1
top
UpperOddField 1PAL
HD (and other interlaced)
All clips in Smoke have a metadata tag showing their scan mode: F1 indicates that the clip conforms to the
same dominant field requirement in the current project settings. F2 shows a mismatch, while P meanwhile
indicates a progressive scanned, non-interlaced clip. This tag is assigned when the material is first imported.
If the tag scan mode appears incorrectly for any reason, it can be changed to match the actual scan mode
of the clip. This is different from other softwares that expose the actual spatiality of a clip's fields.
IMPORTANT Do not confuse Field 1 or Field 2 with the F1 and F2 scan mode tags. The actual dominant field of
a clip showing F1 or F2 in its scan mode metadata may be either the upper or lower depending on the clip's video
format.
In projects containing mixed-resolution clips, interlaced video formats may still be combined despite having
different dominant fields. The differences between the two formats must be addressed however to avoid
outputting a result that displays one of the interlaced video formats improperly and introduces undesirable
visuals. Use the procedure below to correct such interlacing issues.
NOTE The effects are only viewable on an interlaced broadcast monitor.
Reversing Field Dominance
When working in a project that uses clips of various interlaced video formats, the field dominance of clips
that do not correspond with the project settings should be reversed. For example, if a Field 1 dominant PAL
clip is to be included in an NTSC project that is Field 2 dominant, simply reverse the field dominance of the
PAL clip.
About Video Field Management | 181