interlace vs inverse 3:2 pulldown

[odiedog]

i'm converting my avi files using TMPGEnc. under mpeg settings should i go with interlace or inverse 3:2 pulldown. i had old home movies transfered from 8mm to avi now i'm converting to mpeg. thanks.

[greymalkin]

I am assuming the .avi file you now have is interlaced. based on that assumption:

Are you planning on watching these on a tv? if so keep it interlaced.

If you are going to keep them on the pc you will want to de-interlace.

[edDV]

What was the source of the AVI file?
How was the transfer done?

8mm film is 15-18 fps native.
3:2 pulldown is irrelevant since it assumes ~24 fps.

If the current file plays ok to a TV, keep it interlaced.

Progressive frame recovery gets more complicated.

[gastorgrab]

8mm film is 15-18 fps native.

Do you mean that there is no standard speed between manufacturers or that depending on the playback device the framerate can vary that much?

I would think that AviSynth would be an option here.

@ 15fps, if every frame is duplicated then playback would be very close to accurate when played back as progressive 29.97fps.

@ 18fps, if five copies are made of every frame, and then only every third frame is selected, the video would play back "very close to accurate" as progressive 29.97fps. (18*5=90, 90/3=30)

.....that is IF, the difference is because of playback through different projectors.

How was the transfer done?

Should be question #1. The video may already be at 29.97fps.
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[edDV]

8mm/Super8 mm film had no accurate time reference. There were no crystal oscillators, just mechanical drives (often with wind up springs) that determined speed. Likewise projectors had a speed dial so you could manually match speed to what "looks right".

I don't have the good links here but this one will do
http://www.saveyourmovies.com/film_guide.htm

In order to reconstruct frames from a 29.97 fps video, one would have to know the exact speed of the projector. The process could also be done manually by matching field motion to frames.

[gastorgrab]

8mm/Super8 mm film had no accurate time reference. There were no crystal oscillators, just mechanical drives (often with wind up springs) that determined speed. Likewise projectors had a speed dial so you could manually match speed to what "looks right".

Oooh, i forgot about that. Its not just the projector affecting the "Speed Of Old Memories", the camera will add its own degree of error.

Come to think of it, the last camera of that type i used was wind-up.

In order to reconstruct frames from a 29.97 fps video, one would have to know the exact speed of the projector. The process could also be done manually by matching field motion to frames.

In some cases i image you would be ending up with half of one frame, and half of another Super8 as the "Correct" NTSC frame. It's too bad that digital-still, frame capture fixture isn't available at a reasonable price.

Something that attaches mechanically to a film scanner would be better than nothing.
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