How to convert clips from 24fps to 16fps

[denti alligator]

Ok, here's the deal. I have the Italian Raro DVD of Andy Warhol's silent films. These were shot at 24fps but were meant to be shown at 16fps. Annoyingly, the DVD is a PAL (ie sped-up) version of a 24fps projection. I want to slow these down to what would be the equivalent of 16fps. How do I do this?

Is there a program that would let me turn the PAL 25fps (PAL is 25fps, right?) to an exact 16fps? Or should I calculate what the length should be and simply slow down the film to fit that length.

I want to do this without introducing much artifacting or ghosting, if possible.

Any help would be appreciated.

[guns1inger]

The first step would be to see if you can find the pattern of blending use to create the PAL version. If there is a pattern that you can decimate back to 24 fps, you can then reduce the framerate without the ghosting etc being as much of a problem (assuming the 24 fps was simply the projection speed).

[denti alligator]

How would figure out this pattern? What freeware programs would you suggest using?

[manono]

If you simply want to slow it down, then use AviSynth and add:

AssumeFPS(16)

to the script when reencoding. This will also necessitate slowing the audio (if any), and will make it sound horrible. This assumes that it's really playing more than 50% faster than it's supposed to. Personally, I find that a little hard to believe, but I'll take your word for it. Also, if originally put on an NTSC DVD, there may or may not have been some funny business when converting to PAL (ghosting and/or interlacing).

If the aim is to create a 16fps PAL DVD, then it's not quite possible. The slowest you can make it (without duplicating frames) is 16.667fps, followed by the use of DGPulldown to make it output 25fps as required for PAL DVD playback. If this is for an AVI, then there would be no problem with 16fps.

To be sure, can you upload a small 10 second or so section of the unprocessed source somewhere, so we can have a look?

[Alex_ander]

If all the frames are progressive and don't repeat (you can rough-view it in VDubMod using right arrow key for more than 25 frames) there's a chance to slow down the video (if that's the goal) without re-encoding. Demux video in DGIndex (save project and demux video mode) and load it to DGPulldown. Check 'custom' box, type 16.67 for input and 25 for output framerate. This will make DGPulldown assume different input framerate and change duration at applying pulldown. As manono mentioned, you'll need to slow down audio significantly (by 25/16.67 factor).
In all other cases you'll need AviSynth+new encoding. For NTSC output frame interpolation can be used with MVTools plugin but there are chances with a lengthy video to get artifacts at some scenes.

[manono]

Good one, Alex_ander. I had forgotten about that. I don't think there's much chance of it being progressive (one reason why I asked for a sample), but if it is, yours is by far the better way to do it.

[denti alligator]

Thanks, everyone. I'm a newbie, so I'll need just a little more guidance.

I have no idea if these are progressive or interlaced. I'm assuming they're progressive (any easy way to check?).

Sound is not an issue. These are silent films.

How do I get the films themselves (which are part of a longer DVD) into MPEG form to load into DGIndex?

EDIT: I'm using DVDShrink to get the two films I want from the DVD together. Then I'll use DVD Decrypter to convert to MPEG?

Unfortunately I can't upload a clip.

[denti alligator]

I figured it out, using DVD Decryptr instead of DGIndex to create mpeg-2 file. It worked! Now I can't figure out how to burn these slowed-down mpeg-2 files onto a DVD. I can't convert them back to vob files, can I?

[denti alligator]

Actually, it didn't work. The first 34 minute clip ends upbeing only 16 odd minutes, when it should be longer, closer to 40 minutes. Does this mean the clips aren't progressive?

[manono]

I have no idea if these are progressive or interlaced. I'm assuming they're progressive (any easy way to check?).

You check by having a look in a player that won't deinterlace it if it's interlaced. I use VDubMod, scroll to a place with movement and then advance a frame at a time.

How do I get the films themselves (which are part of a longer DVD) into MPEG form to load into DGIndex?

DGIndex opens any type of MPEG video (VOB, MPG, MPV, M2V, etc.). Did you even try and open one of your VOBs using File->Open?

Unfortunately I can't upload a clip.

Eh? Why Not? Just go to Mediafire after you cut a small clip, upload it, and post the link it gives you when done:

http://www.mediafire.com/

Now I can't figure out how to burn these slowed-down mpeg-2 files onto a DVD. I can't convert them back to vob files, can I?

Yes you can. One way is to demux (DGIndex again, open it, and then File->Save Project and Demux Video), followed by authoring to DVD using Muxman. Since there's no audio, you may even be able to get away with renaming the .mpg extension to .m2v before creating the DVD in Muxman or any other authoring program with which you're familiar.

The first 34 minute clip ends upbeing only 16 odd minutes, when it should be longer, closer to 40 minutes. Does this mean the clips aren't progressive?

It could just mean you're playing them in a player that doesn't show the correct length (most of them don't). If they really are interlaced, then they'll play funny (jerky-like), and you shouldn't have run them through DGPulldown, which is only for progressive video. Look, just upload a small section and we'll tell you what you have and how to slow it down.