GKnot guide is confusing concerning Force Film

[unknownsoldierX]

The robot4rip guide suggests to use DGIndex but also says "Since Robot4Rip was made for DVD2AVI, the Auto "Force Film" function will unfortunately not work, so uncheck it." I followed the guide and chose DGIndex.

Back in the GKnot guide it says:
If FPS equals 29.970 you did not choose Force Film in DGIndex and will have to perform IVTC (explained later on in the guide). For now set FPS to 23.976. In all other cases (FPS = 25.00 or FPS = 23.976) you don't have to do anything.

Later on in the GKnot guide:
If DGIndex showed your source as NTSC FILM below 95% you enable Inverse Telecine here (this option is only visible if the D2V has a framerate of 29.97fps). In all other cases set Field Operations to None.

DGIndex shows my source as 29.970FPS NTSC Interlaced. I tried Inverse Telecine and the compression test was combed pretty bad. What do I do?

[CWR03]

Try a couple of tests using both Force Film and None, try some of the Deinterlaced settings. Inverse Telecine is not for interlaced video.

[manono]

Hello and welcome to the forum-

Yes, it sounds like it's interlaced and IVTC won't work. To confirm, open that 29.97fps D2V in GKnot, scroll to a place where there's movement, and then advance a frame at a time. If all frames are interlaced, then you'll have to deinterlace it, and keep it at 29.97fps.

[unknownsoldierX]

I think I may just redo the rip and have robot4rip use DVD2AVI instead of DGIndex. That way I can use force film. Is DGIndex really any better?

[manono]

That way I can use force film.

If it's really interlaced, then you'll be sorry. Maybe you can tell us the name, and maybe someone here has worked with it already.

[CWR03]

You can quickly create a test without having to encode the entire file - using DGIndex, drag the slider forward to a section with motion and click the left bracket, then press F5, let it play for 5-10 seconds, then press Esc and click the left bracket. Save that range once with Force Film selected and again with None, obviously each with a different filename. Then you can load them into GordianKnot and encode with different settings and see what looks right, and each encode will only take a minute or so.

If it's a movie, it should almost always encode properly if you select Force Film, then in Field Operations select None. If it's a series it may take a number of trial runs to figure it out.

[Guest]

If it's a movie, it should almost always encode properly if you select Force Film, then in Field Operations select None. Huh? Force Film and None are direct opposites and cannot be selected together. Also, hard-telecined movies cannot be force Film'ed.

[unknownsoldierX]

I performed the tests like you advised. Combing is noticable in both results.

I've decided GodianKnot is not for me. I just want to rip some NTSC DVD movies to Divx 6. Can you guys recommend an easier program/method for this?

[Guest]

DGMPGDec + Avisynth + VirtualDub

[unknownsoldierX]

Ok, I like using VDub. So, I open the main movie vob's in DGIndex and the information says: 4:3, 29.970FPS, NTSC, Interlaced. I want to convert to Divx 6 and have the smallest file size possible with little to no quality loss. How do I go about changing it to 23 fps?

[manono]

Can you guys recommend an easier program/method for this?

AutoGK (http://www.doom9.org/autogk.htm). The most recent versions (2.16 is the current one) support DivX 6.

[CWR03]

Huh? Force Film and None are direct opposites and cannot be selected together. Also, hard-telecined movies cannot be force Film'ed.

I realize now that I didn't get into enough detail - I meant run DGIndex on the file using Force Film, then after opening it in GordianKnot and selecting Save and Encode, choosing None under Field Operations at that point.

[Guest]

Ok, I like using VDub. So, I open the main movie vob's in DGIndex and the information says: 4:3, 29.970FPS, NTSC, Interlaced. I want to convert to Divx 6 and have the smallest file size possible with little to no quality loss. How do I go about changing it to 23 fps? You have to analyse the video and understand things to do it right. If it is really interlaced, you shouldn't convert it to 23.976 because it will become jerky. If it is hard telecined, you can use Decomb. If it is field-blended you can try some of the unblending tools.

[unknownsoldierX]

I've always figured converting 29.970FPS --> 23FPS would allow for a much smaller file size. From what I've gathered from this thread, it isn't always possible to do wihtout losing quality. Or is it?

[CWR03]

It depends on the source - I've worked with a number of hybrid sources which couldn't be done properly at 23.976fps without portions looking extremely jerky. It's not really "converting" from 29.97 in most cases, but the source is interlaced or telecined to make a 24fps film play smoothly from a DVD. You're just reversing that process and saving about 20% on the framerate.

[jggimi]

Let's try and net out the possibilities: Your content was a 24fps film transfer. In this case, it will have been Telecined to 29.97fps. Only this[/b] type of content can be Inverse Telecined (IVTCed). "Force FILM" is just a quick method of IVTCing. IVTC will re-assemble the original 24fps frames, but at a slightly different speed: 23.976fps. Force FILM can only be used when the MPEG-2 flags allow it.

Interlaced 29.97 video. In this instance, the content is shot with an interlaced video camera. 59.94 times per second, a field was recorded. (2 fields make up a complete frame). This form of content, if it were reduced to 24fps (23.976), would have 20% of the pictures missing. Not good.

A hybrid, containing some stuff that may be film, some that may be video.We have an old tutorial that describes these different types of content, and how to analyze them. Some of the software is out-of-date, but you may still find it valuable: www.doom9.org/ivtc-tut.htm

AutoGK, recommended above, will analyze the content and figure this out for you, if you prefer automation to figuring it out yourself.

[unknownsoldierX]

Thanks for the clear definitions. I'll check out the tutorial evetually. For now I am content just using the AutoGK log. :D

Source resolution: 720x480
Found NTSC source.
Source aspect ratio: 4:3
Analyzing source.
Source has percentage of interlacing in motion areas: 93.34
Source has percentage of telecined patterns: 0.44
Source has percentage of progressive patterns: 3.09
Source has percentage of interlaced patterns: 96.47
Source is considered to be interlaced.
Output will contain 236981 frames