Unexpected BFF using SelectEvery

[Aegwyn11]

Hi, I've got an interesting thing where I'm getting reversed fields when interlacing. I've done a pile of effects, then a composite of several clips, all progressive, and the end result has the fields swapped from what I would expect.

Here's a snip of my script that results in TFF (but I'd expect to result in BFF). Anyone have any ideas why?

#Composite
Dissolve(Slide, Clip1, 60)
Dissolve(last, Clip2, 60)
FadeOut(last, 60)
UnalignedSplice(last, Slide)
Dissolve(last, Clip3, 60)
Dissolve(last, Clip4, 60)
FadeOut(last, 60)
UnalignedSplice(last, Slide)
Dissolve(last, Threeway, 60)
FadeOut(last, 60)

#Upsample to 4:2:2
ConvertToYV16(matrix="Rec709")

#Interlace
SeparateFields()
SelectEvery(4,1,2)
Weave()

[Gavino]

Here's a snip of my script that results in TFF (but I'd expect to result in BFF).
...
SeparateFields()
SelectEvery(4,1,2)
Weave()
I assume you don't have either AssumeTFF() or AssumeBFF() in your script. In that case Avisynth assumes BFF by default, and this order will be used in SeparateFields().

The code with SelectEvery(4,1,2)+Weave() consequently produces a clip interlaced with TFF. If you want BFF, use SelectEvery(4,0,3) (or add AssumeTFF() before SeparateFields()).

[Aegwyn11]

Ah thanks! Seems like I've done this in the past without AssumeTFF, but its been a long time so who knows. I learned something today, thanks!