Removing Field Artifacts

[thecoreyburton]

Greetings!

This is my first post here, I was referred to the forum by a friend in the hopes someone could help me with some issues I'm having so apologies if this is in the wrong place. Firstly, here's a sample of the source. Included are two clips: The first clip is a short section that highlights the problem and the second clip is just for further reference on a scene that has a lot of panning and doesn't appear to have the same problem.

In the first clip, you can notice a flicker in the lines above his head (it is reminiscent to me of a bad interlace). When it cuts to the desks, it's more apparent on the lines on the desk. I did a quick pass of QTGMC to see what result it'd get and the source improved, but not completely. From what I can tell, it's because the animation is done at 12.5fps, whilst the panning is done at 25fps, making the lines fluctuate in groups of two frames rather than on alternating frames. I could potentially fix it by doing the entire source at 12.5, but that'd halve the motion in the second clip. It fluctuates between the two frame rates frequently. The NTSC source has it's own problems, making the PAL source of this show the preference when ripping it.

So my question is, has anyone encountered this before? What's my best bet in going about removing it without completely destroying the video in some way? If you'd like any more information in regards to my problem, any more clips or anything like that don't hesitate to ask and thank you in advance.

[Baldrick]

Sample link without MEGAsync installed:
https://mega.nz/#!SN9CSBxZ!oECQL0JIC7SGr7WZ8K-vAW-t6N-q7AfZtkPd8AtaA74

You can also attach files when you post.

[thecoreyburton]

Attachments will definitely be the easier option in the future! I updated the link in my post with yours and uploaded all the files as attachments as well, thank you.

[manono]

What's my best bet in going about removing it without completely destroying the video in some way?

Try using QTGMC's special treatment for progressive sources with the problems as seen in the samples. It's thoroughly described in the included doc. The lines below were taken straight from the doc, the first for mild cases and the second with a stronger effect (and the one that seems to work better on your sample). Reading the doc might give you some more ideas to try:

QTGMC( Preset="Slower", InputType=1 )

QTGMC( Preset="Slower", InputType=2, ProgSADMask=12.0 )

[thecoreyburton]

Ah, I wasn't aware QTGMC had that ability. You're right though. The first input type parameter clears it up better than any alternative I've tried so far and the second does an even better job. I've got the documentation up right now and I'm trying various combinations and settings on various episodes and clips to see if it holds steady, but in the worst case scenario, QTGMC(Preset="Slower", InputType=2, ProgSADMask=12.0) is definitely an improvement. Thank you!

Edit: I've found so far that subjectively QTGMC(Preset="Slower", InputType=2, ProgSADMask=2.0) gives the best result. Some detail is lost, but considering it's an animated source it's barely noticeable and I don't mind at all. In both cases there is still some "smoothed shimmering" in the desk scene of the first clip, the back desks in particular. It no longer jolts up and down but rather blends back and forth. While this is much more appealing to watch than the source, I'd still like to try and fix it some more and am still looking for some more suggestions. I'll be going over the QTGMC documentation for the next while (along with any other plugin documentation I have) to see if there's anything else that can be tweaked to help.

[manono]

Yes, those QTGMC settings are risky to use on live action videos, but for animations such as The Simpsons there isn't much detail to lose.

There are also anti-aliasing filters you might try, ones such as Santiag:

http://avisynth.nl/index.php/External_filters#Anti-aliasing

But I haven't tried any on your sample so I don't know how well they might work.

[thecoreyburton]

Tried a few different ways and in different combinations and the results are similar again. Almost all of the problem is removed from the roof scene, but the desk scene still has the blending problem. It smoothly moves from one placement to another when in reality the lines should be static. I did however scrub through the source and find what I believe to be the problem. In addition to the artifacts I've previously mentioned, every now and then there's a frame transition like this:




Perhaps the pixelated nature of the frame is interfering with the filters doing their job completely? I managed to get my hands on a broadcast version of this episode and the problem I have is still present, could it be a fault with the original animation perhaps?

[manono]

The animation? No, probably the conversion to PAL is my guess. Or the encoding for PAL DVD. Anyway, if you care so much you can go through and freezeframe the problem places, or use frame interpolation.

[thecoreyburton]

Hmm, still curious as to why it appears on NTSC broadcasts, perhaps they used pal masters for that particular broadcast? For reference this is at around the nine minute mark in Season 2, Episode 1. But fair enough. I might just have to take this as a best-case scenario. I'm all for putting time and effort into this but finding hundreds of problem areas in over 200 episodes simply wouldn't be worth it. Thank you for all your help!