Finding the Base Framerate

[lubczyk]

How would I go around finding the base framerate of an mpeg2 clip whether it be Telecined, Video, Hollywood Film or a Hybrid clip. I think there's a way of doing it in Virtualdubmod but I'm not sure. I just want to know the step by step procedure on how to figure this out.

I've read about Base Framerate around in the forum but haven't figured it out myself on how it is determined. I know that some animes Base Bramerate is anywhere from 8, 12, 16, and even hardcoded 29.97 and sometimes as low as 4 FPS. I'm not quite sure about Hollywood films.

I'm thinking of using Nero AVC with VFR timecodes and mkv to encode my Region 1 movie collection so that I can watch in on PC.

At the moment I'm working on Family Guy Season One. I'm hoping that fingind the Base Framerate will help me get rid of the god awful Bobbing Artefacts and Field Blending.

[LogicDeLuxe]

Hollywood film is 24 fps, like pretty much all movies with audio appear to be.
Video transfer is usually 23.976 for NTSC or 25.0 for PAL. But be aware of ugly TV stations messing around with this in order to place breaks at will.

Animated stuff usually has variable base rates, scenes with little motion can be as low as one frame lasting for several seconds up to full rate in fast motion scenes and pans.

Hybrids have variable base rates either, which is the whole point of a hybrid. Ususally they combine the film rate as above with the native video rate either progressive or field based. In overlaying scenes, there can be several base rates at once.

For region 1 hollywood movies, you have either a flagged stream, which you should be able to reencode without further processing, or it can be 29.97 which needs to be deinterlaced with IVTC.
For NTSC hybrids, they should stay in 59.94. Or if you really want to get rid of the jerky pull down pattern, 119.88 would be the perfect way, though it requires an intelligent script which detects the film parts properly.
Hybrids transcoded to 29.97 is a really bad idea, though unfortunately they do exist.

[laserfan]

LogicDeluxe, your post does not answer the question though, which was "how to find out".

I know that some of the tools I use, including AutoGK and Fairuse Wizard, use some methods (unknown to me) to automatically detect the encoding strategy so that the correct conversion methods can be used. Sometimes they have problems with, for example, DVD movie trailers which are encoded with a combination of video and film.

I think lubczyk asks a good question--there must be some way(s) to look at the program material and identify how it's put together?

[foxyshadis]

If you just want hybrid film/video, that's easy: just use tivtc and follow the directions, and it will take care of everything for you. You can check out avisynth's vfr page (http://www.avisynth.org/VariableFrameRateVideo) (which I'm updating) for other ways of working with it. DGIndex will also report film-to-video ratio if a DVD uses pulldown properly.

For anything other than 24/30:
The manual method is to step through the frames and find out. Rather too much work.

Slightly more automated methods include using dedup or tdecimate mode=4, then examining the log files those produce; you'll notice different sections have their own particular cadence. (take el hazard, which has a lot of weird sections: 14, 16, 18, 20, 24, and even more, I just stepped away and left it all at 24.) But I'm not aware of a tool to automatically detect it, or even one to correct it once you have the information. Tritical said it would take too much recoding of tdecimate when I suggested it.

[laserfan]

Thanks foxyshadis!

:goodpost:

This helps me, hopefully this answers lubczyk as well.

Oh, but one question--how WOULD you "step thru the frames manually" i.e. what app would you use? I believe I've seen a tutorial on this somewhere but can't imagine finding it again very easily. EDIT: I was wrong! The tutorial was a link at the bottom of the page you linked! From "Force Film, etc..":

The easiest way to examine frames is by by saving a small project with Force FILM turned off. Pick a scene with motion, and use the [] buttons. Open the .d2v in Gordian Knot, and advance frame by frame. If you see interlace artifacts in 2 of 5 frames, you are looking at Telecined content.

Is this still the best way!?

[foxyshadis]

That or virtualdub, sure.

If every frame or no frames are combed, it's 30i/p, if they alternate in a 5-frame pattern it's 24p telecined. (I need to update that as well because older equipment would telecine to 3:2, ie, 3 combed 2 clear.)