ivtc, de-interlace & decimatation

[webwonk]

Well, I've search and read all I could find, but I still am a bit confused. Can someone explain to me the process flow of ivtc/deinterlace/decimate. I know that you only ivtc if the video has been telecined from, say, 24 progressive fps to 29.97 interlaced fps (I'm in the U.S.A. so it's NTSC for me); and I know that I need to de-interlace to make the frames progressively displayed; but:

1.) When would I use either Multidecimate or Smartdecimate?
a.) And why?

2.) I've seen modified de-interlacing avs scripts like Tomsbob and Scharfis' creations - when would I use these over Decomb?

3.) For animation - do I use mftools or yatta?

Help!

Thanks.

Web

[gizmotech]

The better question then when is Why do you think you need to use either tool?

The scripts you mentioned are for deinterlacing content which is actually Interlaced, not telecined. There is a very big difference between the two.

Finally, mftools are a series of highly obfuscated scripts designed to extend the known limits of cpu usage while performing little useable gain to a source. They are meant to be replacements, or augmentations (though neither word is truly appropriate for what they do), for current .dll style filters. Yatta on the other hand is a tool meant to be used in modifying the IVTC choices of the decomb package (amongts many other things), and has absolutely no bearing whatsoever on the mf series of "tools"

Gizmo.

[malkion]

"...mftools are a series of highly obfuscated scripts..."

That's funny.

Back to topic, the tools you've mentioned are for specialized needs when performing ivtc. You would have to take the time in learning their proper usage of course. I've yet to use any one of them. If most of your videos are the 29.976 NTSC variety that's 90%+ FILM source, then using Force Film in DVD2AVI will suffice.

[webwonk]

==================
gizmotech wrote: "The better question then when is Why do you think you need to use either tool?

The scripts you mentioned are for deinterlacing content which is actually Interlaced, not telecined. There is a very big difference between the two."
==================

Because my understanding is that if one has video which is interlaced to 29.97 frames per second (NTSC) but which originated as 24 progressive fps film; then one must first ivtc to restore the video to 24 interlaced frames per second then de-interlace to 24 progressive frames per second.

Or, does ivtc restore NTSC 29.97 interlaced fps video to 23.976 progressive fps if content was film without the need for de-interlacing?

Is de-interlace only for content which originated as 29.97 (NTSC)interlaced fps video?

And where does decimation come into the picture? Many questions. Any answers most appreciated.

Thanks guys.

Web

[gizmotech]

IVTC is the process of restoring progressive frames and decimating the frame rate to 24fps. It is a combined process, other was you are just correcting the combing on screen and your source will contain duplicates.

The whole IVTC process is done via the decomb package (or the other two mentioned) though in decombs case it is done by 2 functions, Telecide which returns the progressive frames, and decimate which determines the duplicate frame pairs.

Those deinterlacing filters you mentioned are more commonly for 30fps interlaced video, and are seldom needed (if at all) for NTSC IVTC'd content. (note, not all NTSC content is Telecined... just 30fps)

Gizmo.

[webwonk]

Thanks Gizmotech. I think I've got it now.

If the VOB is 29.97 interlaced fps but was originally 24 fps film then I telecide and decimate.

If the VOB is 29.97 interlaced fps because it was tv or video, then I just telecide to make it 29.97 progressive fps. Right?

But I've heard that most movies on DVD are actually 24 progressive fps natively. How can we just determine the true native framerate and extract it?

Thanks.

Web

[malkion]

It depends on what you want your final product to be. If you want to keep it interlaced, then you're correct. If you want, you can deinterlace after telecide and decimate.

I think it'll help a lot once you understand DVD2AVI usage, whether or not your encode will need ivtc or deinterlacing is really up to you.

[Bogalvator]

Hi webwonk.

Sounds like this thread will help you immensely (I know it did me!):
http://forum.doom9.org/showthread.php?s=&threadid=34696

Originally posted by webwonk
If the VOB is 29.97 interlaced fps because it was tv or video, then I just telecide to make it 29.97 progressive fps.

Not quite: Telecide matches up pairs of fields to get progressive frames - in a purely interlaced stream none of the fields will match, hence they need to be deinterlaced with TomsMoComp, KernelDeint or FieldDeinterlace etc etc.