ForcedFilm?

[samfchen]

Hello,

Following the guide to Gknot and DVD2AVI, I have a source of the following states under DVD2AVI preview:

Frame rate: 29.970fps
Video type: NTSC
Frame type: Interlaced

Do I do ForcedFilm with the source? I seem to see a lot more "horizontal" lines after doing so, but perhaps that might just my imagination. Please inform what should be the easiest method for dealing with this. Do I do ForcedFilm under DVD2AVI and then InverseTelecine or other options under Gknot?

Please help, thank you.

Sam:)

[manono]

Hi-

If you still see interlacing after forced film, then you need a more full strength IVTC. So you do your DVD2AVI without force film (it'll still be 29.97fps), and use an IVTC in GKnot (which will bring it down to 23.976fps).

If you do both forced film and IVTC, then you'll wind up with a 19.xxxfps movie that will be jerky as hell.

[samfchen]

Hello,

Thank you for replying.
You mentioned IVTC in Gknot? How do you do that?
Or do you mean do IVTC with TMpg? I rather do IVTC in Gknot if at all possible, since it is easier (not so computer competant here). Please inform how to do IVTC in Gknot, thank you.

Sam:)

[samfchen]

Sorry about that, I reread doom9's guide and Gknot and figured out how to do IVTC under Gknot.

Question though, with my scenario, how would doing inverse telecine under Gknot be better then doing ForcedFilm under Avi2Dvd? What benefit IS there in doing ForcedFilm then under Avi2Dvd?

Thank you once again,
Sam:)

[DigDub]

Read my post 'Do I IVTC?'. I have a source that is the same as yours - 29.97fps, NTSC and Interlaced. Don't use Force Film in DVD2AVI or IVTC in GKnot. Use Donald Graft's Decomb filters. It works wonders.

[manono]

Hi samfchen-

how would doing inverse telecine under Gknot be better then doing ForcedFilm under Avi2Dvd?

Didn't you say that you still saw interlacing after using Forced Film in DVD2AVI? Usually the guides say to IVTC if the movie is less than 95% Film. Maybe think of Forced Film as a weak IVTC that doesn't work with more difficult material. Then you have to find a stronger solution to the problem. If IVTC'd properly, you won't see any more "horizontal lines".

DigDub's suggestion about Decomb is a good one, but may be tricky to set up if you're not experienced. If you're curious, go to the big Decomb thread in the AviSynth Forum, and you'll find where to get it, and how to set it up within the .avs created by GKnot.

[magicalpig]

Ok. It seems like the IVTC issue is being addressed, but doesn't he still need to de-interlace?

[manono]

Hi magicalpig-

Good for you-digging around to learn things before posting. It seems that my first answer was incomplete. Ahhh, but I was so much older then. I'm younger than that now.:)

Material showing as Interlaced in DVD2AVI, in my experience, can still be IVTC'd more often than not. How do you know? Look at the frames, and don't rely on DVD2AVI to tell you. Particularly with anime, and frequently with Hong Kong films also, what shows as 100% NTSC and Interlaced has been telecined, and thus can be IVTC'd. But the only way to be sure is to look at the frames.

Make a .d2v with no Field Operation (30fps), and then open it in GKnot. Go to different places where there is movement (it's easier to see the interlacing in motion scenes) and advance frame by frame. If every frame is interlaced, then the source was video (created at 30fps), it wasn't telecined, and shouldn't be IVTC'd (well, you could, but the process would bring it down to 24fps and would make the output jerky). So you deinterlace those things. Then if, in every five frame set, you see 3 progressive frames (non-interlaced), and 2 interlaced frames, it was Film, created at 24fps, and telecined to bring it up to 30fps. So you can perform IVTC and bring it back to it's original form.

Ordinarily, with major movies, you can just do a Forced Film and be done with it (but I've been flabbergasted recently to find some older Hong Kong movies that were pure interlace-couldn't even be IVTC'd-could only deinterlace). Ordinarily the ones that show as a mix of Film and NTSC can be IVTC'd. But the only way to be sure is to look at the frames themselves.

And Welcome to the Forums.

[zeronegative]

Manono-

Thanks for your informative post, although so far nothing new. My problem is with certain Jap movies such as Ebola Syndrome and especially Tetsuo. When skipping through the movie, I found that in certain places it _looks_ like the source was telecined, because 3/5 frames are interlaced. However, different parts of the movie show that for certain chapters only 1/5 is interlaced or even 5/5 is interlaced.

My guess is that this is a video-source that has been transferred to DVD in a really dirty way, but what would be the best option to handle this movie? Use DeComb, and if yes, with which parameters? I guess blend=false would be best to remove ghosting?

[manono]

Hi zeronegative-

So you have one of the dreaded hybrid DVDs. As I see it, you have 2 choices, neither of them pretty. If there's not too much of the pure interlaced stuff, or those scenes are relatively static, you might try Decomb with the regular Telecide()-Decimate() and see how jerky the interlaced parts turn out-maybe just do a test encode of those parts and look at the result.

I might prefer the 2nd option which is to use the Mode=1 setting of Decomb. A sample script might go:

Telecide()
Decimate(mode=1,threshold=50)

This will deinterlace the video parts, IVTC the Film parts, but add back one frame to every 4 so that the result will play smoothly at 30fps. There's more information about it in the Decomb Help file. The drawback to using that is that you wind up with 20% larger file size for the same quality when compared to an IVTC'd 24fps .avi.

As for Blend=false. hakko504 (who's one of my gods around here for his astounding knowledge of AviSynth) seems, in many cases, to prefer Blend=false. It does prevent ghosting, but I think it may leave behind some shimmer-flashing in some cases. I usually go with the default blend. All I can say is to try them both and see which you prefer, or which is better suited to your material.

Sorry to be so wishy-washy. In cases such as these, there are no hard and fast rules.

Edit: Damn-a degree in mathematics and I blow a simple one. When you IVTC, you cut the number of frames by 20%. But when you convert from 24fps to 30fps, you'll increase the number of frames by 25%.

[zeronegative]

Sorry to be so wishy-washy. In cases such as these, there are no hard and fast rules.

I know. I've been a DivX ripper for a while now, and know pretty much most of the tricks to create a (near-)perfect rip. I'm glad DeComb was ever made in the first place, because I used to be a hardcore manual IVTC'er (hail TMPGEnc); with DeComb I haven't had to use my knowledge in that for a while...

Since I am ripping more Japanse DVDs lately, I stumble upon more and more hybrids. I wonder how this is possible; are the companies who do the DVD transfers unexperienced, or is it something else?

Anyway, I will try to make a better rip of Tetsuo I than the one I released a while ago (which didn't look bad at all, thankfully). Let's see how it will turn out :)

[manono]

Hi zeronegative-

I guess blend=false would be best to remove ghosting?

I should have mentioned something about that in the first place. But after reading your last post, I'm pretty sure you already know. Blend=false won't actually remove the ghosting. It just won't introduce any more. However, there's a chance you may have blended fields in the source, in which case you may be screwed. You could do a SeparateFields command and have a look.

[areohbee]

Perhaps I'm a little late, but my understanding is that DVD2AVI's "Force Film" Field Op. reverses the effect of on-the-fly telecining of FILM video. If it is not FILM video, it will only make matters worse. I think: Force Film should always be used for Progressive FILM (that runs at 29.97 without "Force Film"), and never for NTSC Interlaced.