SeparateFields (clip)
NTSC and PAL video signals are sequences of fields, but all capture cards that
I'm aware of capture two fields at a time and interlace (or "weave") them into
frames. So frame 0 in the capture file contains fields 0 and 1; frame 1 contains
fields 2 and 3; and so on. SeparateFields takes a frame-based clip
and splits each frame into its component fields, producing a new clip with twice
the frame rate and twice the frame count. This is useful if you would like to
use Trim and similar filters with
single-field accuracy.
SeparateFields uses the field-dominance information in the source
clip to decide which of each pair of fields to place first in the output. If
it gets it wrong, use ComplementParity,
AssumeTFF or
AssumeBFF before SeparateFields.
From version 2.5.6 this filter raises an exception if the clip is already field-based.
You may want to use AssumeFrameBased
to force separate a second time. Prior versions did a no-op for materials that was
already field-based.
$Date: 2006/12/14 22:55:04 $