Confused with "Field Operations"

[DragonFist]

Hello,

My English is not 100% here so my qustion is:

In DVD2AVI running the preview I get this:
Frame rate: 29,970
Video Type: NTSC
Frame Type: Interlaced

I don't save the .avs with Forced film.

Then, In Gordian Knot, what am I supposed to choose in
Field operations?

I go for Inverce Telecine but my avi's get jerky then.
And I don't have the choise of "smart int" as in Doom9's guide.
I have Field Interlaced instead.

I'm using DIvX 5.o2 Pro.

Thanks from Sweden

[jggimi]

If your content came from a video camera, rather than from 35mm film, you do not want to Inverse Telecine (IVTC), since the content has not been Telecined. "Force FILM" is one of several ways, and the easiest way, to IVTC Telecined content.

But not this content. Keep it at 29.97fps by setting Field Operations in dvd2avi to "None" and deinterlace only. You have a choice between Fast and Smart deinterlacing. (There is a bug with Fast Deinterlacing that has been fixed in GKnot 0.26.1.)

[DragonFist]

My source is a DVD which I ripped with Smartripper.

It was mentioned in earlier guides that you should change the fps to 23,976. Your'e not to do that anymore?

[jggimi]

Only if the original source was 35mm film. The conversion to 29.97fps from 24fps is called Telecining. Your source was not film, but video. It is interlaced, 29.97fps, and was never 24fps film.

It's confusing, because the process of Telecining inserts 6 interlaced frame every second.

Read www.doom9.org/synch.htm for more details on Telecining.

[DragonFist]

Thanks for this...Saved my day (and night)

[theReal]

Well, your source could be 24 fps film - for example if your DVD is a copy from Asia or if it is a DVD copy from Laserdisc.
Then you can IVTC it and it will look better than de-interlaced. However, to ivtc such sources can be tricky. Prepare to edit the avisynth skript to alter the settings for decomb, or use another filter instead (like ivtc.dll).

So, if there's a chance that the original source was shot on film and not video, try to ivtc before you de-interlace (test it on a short part, you'll quickly see if it works or not)

[DragonFist]

Thanks,

I tried a small part with IVTC. The picture looked nice but I got a "jerky" movie.

Then I used the fast deinterlaced and got a nice, smooth running movie.

I don't remember if I changed the fps to 24 when I tried ITVC. Maybe that could be cause also. I think I had 29 for fast deinterladce.

I think editing the scripts and use of other filters are in "phase 3" which I haven't reached yet :)

[jggimi]

You seem to still be confused. Perhaps the following explanation will help level set you.

35mm film is 24fps. NTSC video is 29.97fps.

The process to go from 35mm film to NTSC video adds ~6 frames per second. That process is called Telecining. See the link I provided, earlier in this post, for more information. Please.

IVTC is Inverse Telecining. When done properly, it removes those 6 extra frames. The resulting video file will have a framerate of 23.976fps.

Content that displays as FILM in DVD2AVI has been Telecined. Some content that does not show as FILM might have been Telecined. One can only tell by examining individual frames of the content. The link I provided earlier will show you what Telecined content will look like.

There are 4 methods to IVTC with GKnot:

[list=1] Force FILM in DVD2AVI, when the content type is FILM. The project will automatically adjust the framerate to 23.976, and eliminate the correct frames. The rest of these methods use filters which analyze individual frames. They also require manually setting the framerate, or letting Gknot catch the error and adjust it for you.
Checking IVTC in the "Save & Encode" window. This will turn on the DeComb filter set, and use the Telecide and Decimate filters.
You can manually enable the GreedyHMA filter (and .dll file) by removing the "#" in front of those two lines in the .avs file produced by GKnot, converting those from comments to script commands.
Use another AviSynth filter, such as IVTC.dll.[/list=1]Content which has not been Telecined should not be put through any IVTC process.

If the content just needs de-interlacing (video, or a hybrid of video and film), there are 3 ways to do so with GKnot:[list=1] Use Fast Deinterlacing, which cuts the vertical resolution in half
Use Field Deinterlacing, which blends pixels to eliminate interlace artifacts
Use another AviSynth filter, such as Telecide.[/list=1]The choice between these methods will depend on your content.

[theReal]

I tried a small part with IVTC. The picture looked nice but I got a "jerky" movie.Then it's pretty clear - if all of it was jerky (regular "jumping" appears where essential frames were removed) then it wasn't telecined and you have to keep 29.97fps.

[manono]

Yeah-except he said he may have IVTC'd on top of Forced Film (I think).

[theReal]

oh right - I didn't think of that.

Although jggimi explained everything very well and detailed, I'll say the most important thing again:

EITHER Force Film in DVD2AVI (but only if the DVD is reported to be "Film", which it is not in your case)

OR ivtc in Gknot.

Jippieh, 1000 posts - I need to get a life... ;)

[DragonFist]

Thanks guys...

The link you provided is some reading...phuuhhh...

Your are making me almost an expert on this now :)