## 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`, `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: 2005/10/03 16:31:31 $`