Bobbing with Top Field First doesn't work

[kakomu]

I'm having a weird error with some video I've captured. The video in question is NTSC, 29.97 fps interlaced (60 interlaced fields per second) The capture software I used (VirtualDub) recorded with Top Fields First. I captured with HuffYUV and then re-encoded into HuffYUV RGB. I tested with both.

Now, when I do a regular bob, it will default to bottom field first and it will stutter back and forth in the movie because the top fields are first.

When I do a bob with "assumetff()", it will bob the top frame, but will not show the bottom frame. So, it's showing 30fps and doubling each frame to 60fps.

Now, I took a clip from my MiniDV camera and used both BFF and TFF and it bobbed correctly and with the stutter.

Something is wrong with these clips and I cannot figure out what. If someone can help me out figuring out how to solve this problem, I'd appreciate it.

[kakomu]

Never mind. turns out the source was interlaced, but the frames were doubled. So iframe1 contained frames 1 and 2 and iframe2 contained frames 2 and 3.

[thetoof]

iirc, that's called field shifted or something like that and can be solved by any field matcher, as tfm() or telecide(), so you don't have to bob.

[Alex_ander]

it's showing 30fps and doubling each frame to 60fps
If you see interlacing before bob, probably you have field-shifted progressive footage. Then this should restore 30p:

AssumeTFF().DoubleWeave().SelectOdd()

[kakomu]

Ah, thanks much. I'll have to try that tonight.