Inverse Telecine

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Inverse Telecine

Postby Atarashii Hito » Sat Sep 28, 2002 7:04 pm

I would just like a clearer explanation on what this process does and what the best way of doing it is. There seems to be a couple of options of doing IVTC and its all becoming extremely confusing to me... One of the most confusing things to me is the Decomb filter through Avisynth. By using this it gets you IVTC footage, but yet, Premiere does not allow you to edit in progressive Timebase, so then why use this? If someone could break this down and clear this up, it would be very much appreciated. :D
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Postby klinky » Sat Sep 28, 2002 7:24 pm

No progressive timebase?

24fps can defnitely be Progressive, heck really any frame rate can be progessive.

As for IVTC have you checkedo ut mr ErMaC's guide? It's a pretty goo explanation.

My hacked up version:
Film and all things nifty(like anime) are shot @ 24fps. NTSC standard states film needs to be @ 29.97. You can't make NTSC work with 24fps video :\. So the smarty men came up with a way to convert the 24fps to 29.97fps. Since a TV is interlaced, meaning it is either displaying the odd lines, or the even lines on the TV screen at one time, but never both. Then you actually have a rate of like 59.94 "half-frames" or "fields" per second. So basically what these smarty men do. Is they can take the 24fps footage, and create extra whole "frames" by splitting up the frames into fields and then meshing them together. It looks ugly if you view these frames complete, but if you show only one field set at a time, like a TV does then it looks fine.

All that IVTC does is remove these extra meshed frames, since they're not need to work properly on a computer.

As for Decomb, I finally got around to trying it and basically read the help file and did some cut n' paste:

loadplugin("C:\media tools\filters\mpeg2dec.dll")
loadplugin("C:\media tools\filters\decomb.dll")
mpeg2source("evadisc2.d2v")
Telecide(guide=1)
Decimate(cycle=5)

It looks good to me, even though I don't truely understand what all them commands do ;p

Give it a try and see what it looks like, some others may be able to give you some pointers.


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Postby RadicalEd0 » Sun Sep 29, 2002 12:35 am

well heres what I wrote in the other IVTC thread a few threads down;


Inverse telecine dosent really drop any frames, when anime is drawn its always scanned in as 24 frames per second film material (drawing in interlaced is really hard.. if not impossible). So, to be viewable on interlaced televisions, the frames are copied and meshed together and whatnot to generate pseudo-29.97 interlaced material. IVTC un-meshes and fixes this so that the video is returned to its original, full resolution, progressive, 24 fps state.
That has nothing to do with deinterlacing, deinterlacing just blends together interlace lines, causing ghosting, bad motion (depending on how you deinterlace) and low resolution.
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Postby RadicalEd0 » Sun Sep 29, 2002 12:38 am

Oh as for decomb here is the script I use:

Telecide(guide=1,gthresh=50,chroma=true,threshold=30)
Decimate(cycle=5)

the settings under telecide just help give a more accurate ivtc with less mouth interlacing and such

btw klink, nice choice of an anime to attempt ivtcing. good luck :wink:
(gainax... really fucked eva's tc up)
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Postby Atarashii Hito » Mon Sep 30, 2002 8:00 pm

Ok this helps a little, I have read ErMaC's guide numerous time, I understand that part of it, but editing with it is another story. I am just wondering what settings in Premiere should I use when I edit w/ progressive footage, because you can select "timebase" as only 29.97 or 25 fps. And when you select either one w/ Progressive footage, it will add worse scanlines than with the interlaced footage. And isn't progressive timebase 23.978 fps or something like that? I'm begining to think there should just be a guide on how to edit w/ Progressive footage, or am I the only one that is confused by all of this....
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Postby Zarxrax » Mon Sep 30, 2002 8:53 pm

Premiere should have an option for 23.98 fps, which is as close as it will get to 23.976.
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Postby klinky » Mon Sep 30, 2002 8:56 pm

Are you looking at DV settings? Premiere supports 24fps under Video For Windows.

I would just do ivtc using the decomb filter, then take that to premiere. Unless you want to do Zarxrax's crazy looney bin scheme :lol:



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Postby klinky » Mon Sep 30, 2002 8:59 pm

You can set your video settings to 23.98, but your timebase will only 24fps :\ Which I think could lead to slightly off synching :|


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Postby Zarxrax » Mon Sep 30, 2002 9:32 pm

I dont think the timebase effects the synching. If I understand correctly, It just effects the time display. I normally set that to frames, so I can just see the frame number I'm on...
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Postby klinky » Mon Sep 30, 2002 11:32 pm

You may be right there :O Of course the timebase could also be used to calculate keyframed effects :\ Not sure. My brain feels a little dry at the moment. I'll try to figure out what is what then get back to you :p


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Postby ErMaC » Wed Oct 02, 2002 3:37 am

The timebase is used when previews are generated as well as for keyframing effects. If your FPS and timebase are different you will wind up with sync issues.
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