Strange deinterlace results!

[soujir0u]

I wasn't sure where I should post it, so I figured I'll post it here since I'm using XviD to encode.

Anyway, I'm using Decomb to deinterlace my clip. It's a hybrid clip with some telecined and non-telecined parts. I'm using Telecide with post processing to get rid of the combing effects. The problem is that on some scenes, the text keeps flickering. I've attached a sample clip. In this case, the flickering is with the text on both sides. On another scene, the problem is with the text on the middle of the screen. Otherwise the rest of the clip is perfect.

Anyone know how I can get rid of this flickering? The original source does not have this problem (the text is not combed, only the moving picture is).

[Uli]

I have'nt seen your clip yet, but it's often, that the text is pure NTSC @ 29.97 and the picture is FILM @ 23.976. So decomb takes 'the most important' part i.e. the picture for the combing, resulting in flickering text. So i consider it normal.

greetz, Uli

[morello12]

You need to disable post processing on the telecide filter, by telling it, "post=false". I had that same problem before.

IMO the best/Ultimate settings for deinterlacing are:

1)Area Based Deinterlacer, edge detect 50, threshold 27
+
2)Smart Deinterlacer, fram and field differencing, blend, cubic, motion threshold 20, scene change 100, field swap before and after.

(In addition to decomb/telecide)

http://arstechnica.infopop.net/OpenTopic/page?a=tpc&s=50009562&f=67909965&m=9410996964&r=8270968974

If that doesn't work, narrow down the problem. Use avisynth by itself. Does the problem show up? If so, then avisynth is doing something else funny. If not, add your filters one by one, until you find the source of the problem, but i'm guessing it's telecide post-processing related.

[soujir0u]

OK, I'll try it out when I have time. Thanks!

[soujir0u]

Yup, turning off Postprocessing solves the problem. But now I get some combed frames that weren't cleaned up. So should I use smart deinterlacer now after telecide?

[morello12]

I would recommend the above combination. As per the thread I linked to, smart deinterlacer is an incompentant deinterlacer by itself :)

-morello

[soujir0u]

Are these filters available as Avisynth plugins or are they Virtualdub only? Also, where can I get them? Thanks!

[manono]

Hi soujir0u-

One thing you might try first, since the filters morello12 mentioned are VDub filters, is to weaken the Decomb deinterlacer. At default settings it has a tendency to deinterlace good frames, leaving them flashing-shimmering as you described. So you might try:

Telecide(threshold=30) or 40, or 50.

But it's not guaranteed to work, and you might wind up taking morello12's excellent suggestions. You can get them here:

Area Based Deinterlacer (http://home.bip.net/gunnart/video/#deinterlacearea)

And here:

Smart Deinterlacer (http://sauron.mordor.net/dgraft/)

And then click on "Mine".

[soujir0u]

Thanks for the suggestion, manono, but even changing the threshold gives the same problems. I have tried morello12's method, and it improves things a lot! Although there still is a slight shimmering, but a lot better. What I get now are a lot of blended frames, even when I use interpolation instead of blending. With Decomb I didn't get any blended frames if I set blend=false...

[manono]

Hi-

Have you tried all the tricks to get rid of the interlacing without having to resort to using the deinterlacers? Have you experimented with turning on Chroma, and especially the Guide, and experimented with Gthresh settings? Usually Decomb doesn't have much trouble with regular movies. It's the anime that gives it a workout.

You're setting Post=false in Decomb so those other deinterlacers can do their work? If you don't, then it is still blending by default. Maybe post the .avs and the settings for the two deinterlacers and morello12 can help out again.

[soujir0u]

Hi!

Before I tried morello12's method, I was using:

Telecide(chroma=true,blend=false)

There are no combed and blended frames with this. However, I get lots of that shimmering effect on text.

With morello12's method, I use:

Telecide(post=false)

Then use the 2 Virtualdub filters with those settings he gave.

Perhaps I should play around with decomb's gthresh values?

[manono]

Hi-

A lot of people seem to prefer the Blend=false setting, but I'll take the blending over the flickering that interpolation introduces any time. But to answer the question, yes, if I were you I'd turn on Guide and play with Gthresh settings from 0-100 and see if you can get rid of the interlaced frames that way. Pay special attention to Gthresh settings around 50 or 60. It's worth at least trying because if it succeeds, then you can turn off all post processing.

[soujir0u]

Messing around with decomb, didn't help much. I guess I'll just stick with Telecide(post=false) and use morello12's settings. Blending doesn't look bad at all when I play the video, so I guess it's ok.

[primitive]

If you read the Decomb documentation you'll find that there's an option for the Decimate function that will fix your problem; I think it's guide=1 but I'm not sure. I remember the developer of Decomb talking about his work in the big thread in the Avisynth forum and mentioning that that switch was just the thing for hybrid content such as Serial Experiment Lain (where a lot of 23.976fps material is overlayed on top of 29.97 material).

-p

[soujir0u]

You mean:

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

I have tried that, it still gives the flickering text problem.

[soujir0u]

Ok guys, this should be my last question for this thread. Can I apply the 2 deinterlace filters after cropping and resizing, or is it better to use them before cropping and resizing?

[Aktan]

Deinterlace Filters cannot separate the fields correctly (aka detect interlace) if you crop and resize. So do it b4 crop and resize

[trbarry]

I think if what you are cropping contains garbage then you might get better results if you cropped first, before deinterlace. This would certainly be true with GreedyHMA and probably for the other deinterlacers. And it would also probably mske it run faster.

But you should always deinterlace before resize or most other filters because they tend to blend and confuse things.

- Tom

[Shayne]

I have found this works qquit nicely on some sources

Telecide(guide=1)
Decimate(cycle=5)