Recent comparison of deinterlacers?

[LigH]

Not sure where to put, as it is not really specific to e.g. AviSynth, VapourSynth or ffmpeg as hosting system...

I know a few more or less good deinterlacers (including basic video manipulation functions): Weave, Bob, KernelDeint, Yadif, TDeint, QTGMC... But I was surprised during the last week when a thread in the VideoHelp forum asked about libavfilter deinterlacers integrated in ffmpeg. They mentioned BWDIF, which I learned means "Bob Weave De-Interlacing Filter".

I never heard of that one. Completely missed any kind of discussion about it. And completely misunderstood it from its basic sounding name, thought it only applies "bob" or "weave", without any smart interpolation. I only marginally noticed the existence of its predecessor, w3fdif (Weston 3 Field De-Interlacing Filter). Now that I learned about them, I found that BWDIF already exists for a while and has been discussed, completely unnoticed by me.

So I wonder, is there a thread I should know if I am curious how good it is in specific cases of complicated material? Did anyone recently test several deinterlacers to handle a hard task?

[kolak]

BWDIF is ok, but nothing crazy good. Better than w3fdif, YADIF, but not really on pair with motion adaptive ones.
BWDIF is "based on yadif with the use of w3fdif and cubic interpolation algorithms". It's relatively fast, which is its best feature. Don't expect miracles, but it's good choice when trade between quality/speed is important.

In avs, vs there is really nothing better than QTGMC. In pro world you have deinterlacing in Alchemist (Alchemist File now), Tachyon which are similar to QTGMC (in some aspects better in others worse). They are fairly quick though as they use GPU.

You have BWDIF in vapoursynth as well.

[LigH]

I could test on my own, but I don't think I have much "known hard" material... are there notorious public samples?

[Reel.Deel]

Originally Posted by LigH

I could test on my own, but I don't think I have much "known hard" material... are there notorious public samples?

About 10 years ago Didée posted an SD interlaced clip (now gone) that is problematic for some deinterlacers: SAT1.FFS.2011.03.21.m2v /// (archived)

Here's a clip of the scrip below: deint-comparison.mp4

DGSource("SAT1.FFS.2011.03.21.dgi")

a = QTGMC().Subtitle("QTGMC()")
b = BWDIF(field=-2).Subtitle("BWDIF(field=-2)")
c = DGBob(mode=1).Subtitle("DGBob(mode=1)")
d = PVBob(mode=1).Subtitle("PVBob(mode=1)")
top = StackHorizontal(a,b)
bot = StackHorizontal(c,d)
StackVertical(top,bot)
AssumeFPS(10)

• DGBob() is a fast stand-alone CUDA filter that implements the YADIF deinterlacing algorithm.
  
• PVBob() is a stand-alone version of the PureVideo deinterlacer.
  
• Here's the same clip compared against MSU Deinterlacer 2.0: https://forum.doom9.org/showthread.p...67#post1560767

It would be nice to see some results of ML deinterlacers, if anyone has access to them.

[poisondeathray]

You can use border=true for QTGMC to avoid those flickering border artifacts at the top

[FranceBB]

Originally Posted by kolak

BWDIF is "based on yadif with the use of w3fdif and cubic interpolation algorithms". It's relatively fast, which is its best feature. Don't expect miracles, but it's good choice when trade between quality/speed is important.

Yep, it's mostly noticeable when there are like graphics in sports while the background is truly interlaced with players moving. Bob() would make fields jump up and down like crazy, yadif() would be slightly better, but still jumping a bit, TDeint() will try to get it right but would probably create nasty artifacts in some scenes, BWDIF() wouldn't make them jump (maybe just a bit), but there would still be aliasing.

Originally Posted by kolak

In avs, vs there is really nothing better than QTGMC.

There's nothing better than QTGMC() period, even outside Avisynth and VapourSynth.
In QTGMC() they would not jump at all and there would be no aliasing, as if everything was really progressive.
This is for new sources. When it comes to old sources, QTGMC() shines 'cause it can even get rid of some analog stripes and other kind of noise, thus delivering a clean and perfect picture.

Originally Posted by kolak

In pro world you have deinterlacing in Alchemist

Alchemist is used for live feeds, so it makes sense if you get like a 30i feed that you may wanna bob to 59,940p, blend to 50p and re-interlace to 25i in the best possible way, or for instance if you get 29,970p live feeds that you may wanna interpolate to 50p (instead of just blending it to 50p) and divide in fields to get 25i, all live, via SDI, but I wouldn't use it for files.

Originally Posted by kolak

Tachyon [...] similar to QTGMC (in some aspects better in others worse). They are fairly quick though as they use GPU.

Screw Tachyon and screw Telestream! It costs an eye and a leg, it's closed source, proprietary, you have no control over lots of stuff and it only works on proprietary hardware (like, you can't even have any NVIDIA GPU you like, you gotta install Lightspeed servers for thousands of euros).

QTGMC() is free, open source, totally customizable, tweakable and it works everywhere on CPU and on any NVIDIA card if you use KTGMC() with OnCUDA() in Avisynth.


For file-based workflows, I use BWDIF() when time is important and QTGMC() for everything else (like for UMatic, BetaCAM, 1 inch type c remastering workflows etc). It's the right way to do it, it's the open source friendly way to do it and it's the way that supports this great community we're part of. I've sent those files everywhere to different studios (and obviously aired them) and Avisynth / FFAStrans has been praised by other TVs and professionals. I mean, honestly, in this day and age there's literally no reason to go for ultra pricey stuff from Telestream when they literally add nothing to what open source has been capable of doing for years and the sooner companies toss their products and begin embracing open source, the better, 'cause it means that more and more professionals will contribute.

[Katie Boundary]

Originally Posted by kolak

BWDIF is ok, but nothing crazy good. Better than w3fdif, YADIF, but not really on pair with motion adaptive ones.

Yadif IS motion-adaptive :\

Originally Posted by kolak

In avs, vs there is really nothing better than QTGMC.

Unless, of course, you're dealing with non-linear field behavior. Or you care about keeping the original scanlines intact.

Yadifmod2 + Nnedi3 delivers "more correct" results by default, even if it doesn't look as good as QTGMC in certain cherry-picked scenarios, but it still can't handle some types of non-linear field behavior correctly.

TFM(mode=0,pp=0,micmatching=0).converttorgb().blur(0,1).sharpen(0,1) is the "safest" choice in the sense that it doesn't have any really spectacular failure modes no matter what you throw at it.

[tormento]

Originally Posted by Reel.Deel

About 10 years ago Didée posted [/URL] an SD interlaced clip (now gone) that is problematic for some deinterlacers

The clip I posted in the Cowboy Bebop thread has (on purpose) 29.79p, 23.976p and 60i frames. It could be a nice test bench.

[poisondeathray]

Originally Posted by Katie Boundary

Yadif IS motion-adaptive :\

Not really; at least not what is usually meant as "motion-adaptive", such as BWDIF

BWDIF will weave (the "W" in BWDIF stands for weave) a static content scene resulting in full resolution, yadif will deinterlace it resulting in ~1/2 spatial resolution

TFM(mode=0,pp=0,micmatching=0).converttorgb().blur(0,1).sharpen(0,1) is the "safest" choice in the sense that it doesn't have any really spectacular failure modes no matter what you throw at it.

The "failure" is 1/2 temporal resolution loss and aliasing

[kolak]

Originally Posted by FranceBB

Alchemist is used for live feeds, so it makes sense if you get like a 30i feed that you may wanna bob to 59,940p, blend to 50p and re-interlace to 25i in the best possible way, or for instance if you get 29,970p live feeds that you may wanna interpolate to 50p (instead of just blending it to 50p) and divide in fields to get 25i, all live, via SDI, but I wouldn't use it for files.

Alchemist box is not as good (as it has to work in realtime and it's old) as new Alchemist File sold by Grass Valley now. Price is acceptable for pro market (way better than old box) and offers much more. Old box is not sold anymore, is it?
It has good and bad sides- not much of a control is bad side. If you have combing on small portion of a frame it will treat it as progressive and you have no control over it. Frame reconstruction itself is very decent, but if you want to get totally new progressive file (don't care about original fields, which is the case for most scenarios) QTGMC is better. Alchemist is much faster though- all you need is GTX 1080.

Of course Tachyon is not Telestream, which just license it. It's the most common app where you can actually use it and I agree that pricing is as of today very questionable. You could probably license engine from Cinnafilm which gives very detailed control over processing.

[kolak]

Originally Posted by FranceBB

For file-based workflows, I use BWDIF() when time is important and QTGMC() for everything else (like for UMatic, BetaCAM, 1 inch type c remastering workflows etc).

I do about the same as it's all about automated processing where quality is important, but needs to be just at acceptable level.
BWDIF is used with combing detection, so for hybrid masters I don't break 95% (it's all set to be oversensitive, so I don't miss combing) of progressive parts.
This processed few million minutes now

[kolak]

There is also an important detail- do we need deinterlacing to single or double fps?
It's very important as single one is way simpler and way easier to achieve (with simpler/faster deinterlacers).

[Emulgator]

https://videoprocessing.ai/benchmarks/deinterlacer.html
Realtime visualisation of a selectable sample rectangle.
I hold my breath for MFDIN L Deinterlacer, hoping to become public.
https://arxiv.org/abs/2109.14151
https://arxiv.org/pdf/2109.14151
Tokyo Market looks well, other samples are jagged, don't seem to be interlaced...
Missing QTGMC though...why,MSU?

[PatchWorKs]

...my question is: which is the best FFMPEG deinterlacer ?

[poisondeathray]

Originally Posted by PatchWorKs

...my question is: which is the best FFMPEG deinterlacer ?

On most sources, bwdif

But there are some cases where bwdif produces worse results than yadif (bwdif produces "sharper" results and the "sharp" artifacts can be worse in some cases)

[Katie Boundary]

Originally Posted by poisondeathray

BWDIF will weave (the "W" in BWDIF stands for weave) a static content scene resulting in full resolution, yadif will deinterlace it resulting in ~1/2 spatial resolution

YADIF will then compare each interpolated pixel to the pixels in the next and previous fields and perform temporal smoothing if appropriate. A static-content scene run through YADIF is indistinguishable from a field-matched one.

Originally Posted by poisondeathray

The "failure" is 1/2 temporal resolution loss and aliasing

Neither of those things happens unless the content was originally 60hz or 50hz natively interlaced.

[richardpl]

ESTDIF is better than YADIF and BWDIF combined.

[poisondeathray]

Originally Posted by Katie Boundary

YADIF will then compare each interpolated pixel to the pixels in the next and previous fields and perform temporal smoothing if appropriate. A static-content scene run through YADIF is indistinguishable from a field-matched one.

The yadif deterioration can be less noticable if the source has low effective resolution to begin with. eg. If the static scene has been selectively lowpassed, or uses thick fonts, or is blurry. You should notice the static scene yadif quality loss on fine static credits, static scenes with buildings, windows (lines at certain angles), higher quality scenes with higher frequency detail, and/or static scenes in mixed content cartoons/anime where you might be applying a deinterlacer instead of field matching. Yadif will degrade it signficantly more than if the field pairs were simply weaved. The yadif quality loss is measurable/quantifiable with test charts. Also, yadif 2x will tend to cause flicker in a static scene.

Sometimes bwdif can have detection problems, but the avisynth version of bwdif has a threshold setting. Tdeint is another option for mixed i/p content or with static scenes using tryweave=true

Neither of those things happens unless the content was originally 60hz or 50hz natively interlaced.

And that's what this thread is about. "Deinterlacers" . 50Hz or 60Hz interlaced content (Or mixed content that contains some interlaced content) is usually why one uses a "deinterlacer" instead of a "field matcher". "Deinterlacer" in this forum implies interpolation from a single field

Originally Posted by richardpl

ESTDIF is better than YADIF and BWDIF combined.

It's probably source dependent, but estdif (default settings), looks significantly worse on that sample in this thread in terms of aliasing and bob flicker. Maybe the default settings are not ideal ?

[kolak]

Also (if I remember well) way slower.

[VictiniSter]

I'm curious, how does BWDIF compare with yadifmod2? For some stuff I'm working on, QTGMC results in static elements like logos move up and down from one frame to the next when doubling the frame rate. I was recommended yadifmod2 because it handles static elements better.