BAD IVTC... Why?

[FreierGeist]

Hi all!
:)
if someone please could help me...
this is not the first time that i have the same problem
this problem occour only in pure NTSC AND pure INTERLACED sources
i make a .d2v @ 29.970 (without ForcedFilm) and i apply a IVTC (default settings) and a SmartDeinterlace (default settings) at GKnot.
but the results become crappy
looks like it flickers because the IVTC plugin doesnt insert some frames
:(
i though the problem was on my system, then i formatted and reinstalled everything
but the problem persists
nwo, or the problem is on a possible bad DVD authoring, or i'm doing something wrong (maybe the plugins settings) and i don't know what.
:(
please... enlighten me
:)

THANKS

[jggimi]

Don't IVTC your NTSC video sources. De-interlace, if needed, but leave at 29.97fps.

IVTC (Inverse Telecine) is only used on sources that were transferred from film.

[Asmodian]

I thought most NTSC video sources were transferred from film (at least isn't most US TV shot on file then telecined to 30fps?)

@FreierGeist
Have you tried an alternate (better IMHO) IVTC solution (decomb's telecide/decimate combo)? If not I would give that a try, unless you are sure your source is untelecined, of course. You could step through your unprocessed (or just deinterlaced) source and see if there was a duplicate frame every 5 frames.

[jggimi]

Most "Region 1" DVDs are 29.97fps, true. They are all, obviously, video.

But the source from which they were derived will vary. Most "films" are shot on film, and distributed on film, and will be a 24fps source that is then Telecined to 29.97fps.

"Made for TV" content is usually NOT film. It was, in the 60s, but the advent of reasonable quality video tape for broadcast use means that much direct to broadcast content is not Telecined.

Examples might be:
Concerts
TV shows
Some "made for TV" movies/animation
"Direct to Video" content not intended for theatrical release
This last is real common for sequels to successful children's movies: e.g.: Lion King II

[Kyo]

I encode one ep. of Trigun and dvd2avi say me NTSC+Interlaced
i use IVTC(normally for anime content) and the result=bad(interlaced frames, too blurry...)
whe use smart deinterlacer on nandub = good!!!!! (clean, cool :)...)

May be your case.

[FreierGeist]

i tried Decomb in another DVD source
the result was better than the Inverse Telecine gave me
but, the "flick" wasnt slipped away :(
and the "crappy results" was only about IVTC, my Deinterlace function was "perfect" (not even 1 horizontal line)
ps.: thanks to all replies
;)

@ jggimi: tahnks, but... why keep the 29.970 fps?
23.976 gives a smaller file size and the same quality, right?

@ Asmodian: how do i get those technical infos about the source?
is there a way of getting these infos from the .VOBs?
or i have to look at the "publisher" site?

hmmmmmm
so...
thanks again!
:)

[jggimi]

why keep the 29.970 fps?
23.976 gives a smaller file size and the same quality, right?
Because your content was created at 29.97fps. 23.976 is only for content originally created by dipping it in chemicals, with sprocket holes on the sides.

My recommendation is to never Inverse Telecine any content that has not been Telecined. IVTC is causing your pain, so stop doing it, and the pain will stop.

[Asmodian]

@FreierGeist
You could just step through the video using virtual dub or some similar program without any decimating and see if you can notice one in five frames as a duplicate (or blend), they have always been fairly obvious on telecined video during a pan (at least to me). I don't know any other way to figure out the source type of a vob.

[diji1]

Because your content was created at 29.97fps. 23.976 is only for content originally created by dipping it in chemicals, with sprocket holes on the sides.

... errr, so why don't you perform IVTC ?!? I belive FreierGeist to be correct in saying that it leads to higher quality at the same filesize ...

[jggimi]

1) Because you don't IVTC content if it wasn't TC'ed to begin with. You'd be eliminating 20% of your content.

2) As FreierGeist described, IVTC was causing pain. "If you're sticking your finger in your eye...don't complain that it causes redness and difficulty with depth perception."

[diji1]

1) Because you don't IVTC content if it wasn't TC'ed to begin with. You'd be eliminating 20% of your content.
could you explain that ? presumably to go from 24 -> 29.97 fps duplicate frames are added so ... ( pls correct me if im incorrect ), doesn't removing them mean u more or less just have the original ?

... IVTC was causing pain ...

with that attitude you miss out on the warm feeling of satisfaction that comes from finally beating down that really difficult dvd and making the backup *perfect* :)

[jggimi]

could you explain that ? presumably to go from 24 -> 29.97 fps duplicate frames are added so ... ( pls correct me if im incorrect ), doesn't removing them mean u more or less just have the original ? In this particular case, the content did NOT go from 24 to 29.97. It started at 29.97.

Therefore, there had been no Telecine process to Invert. Note the title of the thread ... "Bad IVTC."

[FreierGeist]

thanks you all
:)

if i'm right, jggimi says that there's some sources that are not Telecined (movie is usually made on a 35mm film negative, but some isn,t, right?)
as robshot said: "NTSC Video is a "field-based" format of 59.94 FIELD per second. A Field is the smallest unit in Video format. 2 Fields made up into 1 FRAME. So, this 59.94 FIELD per second equals 29.97 FRAME per second."
but, in his article, he doesn't mention the non-telecined or the "original" 29.970 material.
so, i suppose that jggimi its saying that these "original" 29.970 sources shouldn't be "drop framed" (IVTC).
Doom9 said to me that Decomb or GreedyHMA can handle and IVTC even these source...
i got say that.... i'm quite confused :confused: :)

[]s

[manono]

Hi FreierGeist-

I suspect that jggimi is right in your case. But to be sure it has not been telecined, and therefore should be kept at 29.97fps and just deinterlaced, you can do this. Take your 29.97fps .d2v and either open it in GKnot, or make an .avs or a VFAPI and open it in Nandub. Find a place where there's movement-action. Step through it frame by frame. If you see interlacing in every frame, then do it in another place. If again only interlaced frames, then you have no choice but to keep it at 29.97fps and just deinterlace. But if you find some good frames (non-interlaced), then it has been telecined (at least part of it anyway), and you can perform IVTC on it.

[FreierGeist]

THANKS manono!!!
thanks big time supreme forever r0x!
:D

[manono]

Alright! Good for you.

Problem solved? So what did you discover? When you test that way, 2 of every 5 frames (or is it 3-I forget) will be "good" frames in a repeating pattern if it has been telecined, and then you can Inverse Telecine (IVTC) it. Otherwise slap on Decomb's FieldDeinterlace or something else and be done with it.