general deinterlace and ivtc tutorial needed

[graysky]

I mostly wanna deinterlace and ivtc hybrid material from NTSC source (mostly film says MeGUI.)

I've been playing around with decomb but am wondering if there is some general guide to hybrid material I can read and learn from out there somewhere? MeGUI's analyze feature uses plugins and code there is alien to me. Sometimes it looks okay, other times my decomb avs's look better.

Thanks all.

Example section from MeGUIedeintted = SeparateFields().SelectEven().EEDI2(field=-1)
tdeintted = TDeint(edeint=edeintted)
tfm(order=-1,clip2=tdeintted).tdecimate(hybrid=1)

Example section from my avs I made from the decomb docsAssumeTFF()
Telecide(guide=0,post=4,vthresh=30)
Decimate(mode=3)

Thanks all!

[neuron2]

Since such a tutorial does not exist, you should research and write one. :)

[graysky]

@neuron2: Ha! If I had the knowledge base I would! Did you ever get a chance to have a go at making that master flow chart you spoke of a few weeks ago? Something like that would be very helpful.

I've decided it is now time to write my own. Check back in a week or two. :)

[foxyshadis]

Look in the 2.5.7 avisynth release's documentation, under docs/english/advancedtopics/hybrid_video.htm to find whatever the most recent update wilbert and I had was.

I wonder what happened to the wiki page on it? Man, with the lost 3 months or so, I'm all confused about what's in it and what isn't. Now that I see it's just not in there at all, I'll reupload it.

VFR page. (http://avisynth.org/mediawiki/VFR) It still needs a lot of editing though, and I'm way too tired right now. There's also a couple parts that could stand to be updated with new tools, the mp4 timecode ones in particular, but for the most part I don't see much that's changed in the last year. How to integrate it into the workflows of various GUIs would be a good topic though.

Of course any clarifications, revisions, simplifications, etc are all welcome. (If you want to see how cruel its methods used to be, see the old page, which came with 2.5.6.)

[graysky]

I'll check out the docs you mentioned. Thanks for the link too, but I didn't really find the info all that useful since it's just suggested scripts with little explanation of how and why they're written they way were.

[foxyshadis]

What sort of why do you want? I'm just curious what would make it better. Why you would choose one method over another? Why hybrid exists? Why simple deinterlacing wasn't used, or a mode like MeGUI's? (MeGUI didn't even have deinterlacing then, I think.)

They're pretty minimal, I'll admit, but that was kind of the point; they show you how to deal with hybrid without introducing a lot of unrelated filters and suggestions. I did try to explain the drawbacks, but I can see how it could be more upfront. Going to CFR is the simplest and most compatible but means some level of either blending or judder or both; 120fps is 'perfect', easiest to edit but hardest to play; vfr is also 'perfect' but just a pain to edit - the attraction of vfr is that it's logically equivalent to 120fps without the large storage and processing overhead. You choose depending on what you need and how much work you want to put into it. (MeGUI needs minimal work, and thus uses the first, 24p CFR, with some blending and minimal judder. It could be modified to fit the vfr-timecodes workflow seamlessly, but it would be a pain to write and slow down the encoding.)

How they were written is easy: Just looking over the docs (plus threads here) to determine what options are related to hybrid video, and which cause what behavior. They're as simple as possible, after which you can have all the interlacing junk out of the way and concentrate on building your script with purely progressive video.

MeGUI does tend to detect hybrid a lot more than it needs to, though, and really overuses that EEDI2. It's great quality when it makes it into the output, but in most movies detected as hybrid, only the intro/credits actually are; between the deinterlacing and the blending you'll never see a difference compared to dropping eedi2 altogether.

Now that I think about it, encoding and decoding could probably also be split up. And a pretty glaring omission in the wiki is blended fields. I never have to deal with PAL, though, so I can't write that one.

[graysky]

What sort of why do you want? I'm just curious what would make it better. Why you would choose one method over another? Why hybrid exists? Why simple deinterlacing wasn't used, or a mode like MeGUI's? (MeGUI didn't even have deinterlacing then, I think.)

I think a guide written more to answer your second question would be very helpful (why you would chose one method over another). As well, I'd like to read about why MeGUI selected the options it does when it analyzes a video.

Also, the section entitled, "Opening MPEG-2 hybrid video in AviSynth and re-encoding" inside hybrid_video.htm is a great start, but to me would be much more powerful if it was expanded to explain which method would be best given a particular type of material. Many example scripts are always a good idea in my opinion.

Right now I'm using decomb (see my original post) to handle the video followed by a decimate command. I'm not that impressed with the output. I'd like to read more about the script MeGUI selected for me to use as an example at this point and compare the output of that plus me tweaking it according to the teachings of a good guide before I commit to using the script as a default for hours of the same hybrid video :)

Thanks for your interest!