# SeparateFields

`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` before `SeparateFields`. If it gets it really wrong, you may want to use `AssumeFrameBased` also.

This filter has no effect if the clip is already field-based.