Interlacing progressively confuses me

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jcdenton
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Interlacing progressively confuses me

Post by jcdenton »

There are still some questions about interlaceing that are driving me crazy.

Ok, I know DV Material is always interlaced in the "Bottom Frame first" Mode. I also try never to deinterlace stuff to make shure I won't get blured images. If I play an interlaced movie on a TV, it looks just right, while it may look strange on a PC monitor. So I edit and save everything interlaced (bottom frame first).

Now what confuses me is:

If I edit a movie with multiple scenes etc. and for some reason one scene starts with a topframe and an other scene starts with a bottomframe, or the number of frames of a scene is not even, so in the end I got some of the scenes starting with a bottom frame and some of them starting with the top frame, could this mess up the whole thing?

(I'm not talking about diffrent mode material ("bottom-frame-first" vs "top-frame-first" )
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RE: Interlacing progressively confuses me

Post by Raptor »

It is top and bottom FIELD not frame, two fields make up a frame, each containing half the frame information - what is referred to as 60i 60 fields make 30 frames ( 29.97 ) So theoretically you can't split fields.
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jcdenton
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RE: Interlacing progressively confuses me

Post by jcdenton »

yes, of course. (well here they use PAL, that is 50 Hz). In the end you get 25 frames/s. Both half-frames are put onto a frame. But there's a diffrence of video recording at 50 or 60 Hz and Film recording at 24 Hz. If you convert Film to Video, it will be interlaced, but each pair of half frames is taken from a frame that was shot in one single moment.

When recoding video with eg. a DV Camcorder, each half-frame will be taken at it's own moment. So there is a time diffrence between the top field and the bottom field (unlike Film).
DV Material uses BFF (bottom field first) by default.

DVD sources usually are in TFF. When you export TFF Material as BFF, you'll get an ugly trembling, shaking effect. Sou you should not mix TFF and BFF unless it is made from Film.

But I was talking about BFF only. I have kind of answered this question to myself:
I realize that my question was pretty dumb :)

Since the video is saved in 25 Full frames, I will never have the chance to mess up the order of the fields. So I shouldn't worry too much. Just make sure not to mix BFF and TFF source Material. I also started to BFF-interlace 3D Animations. Currently it's a simple 2-frame inerlacing, but I have some ideas for saving the 3D animation with 200 fps and then interlace it with 4 curve-blended frames per field to get some motion blur FX.
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