Restoring resized interlaced videos

[Lirk]

Some source videos which uploaded to YouTube was in PAL format (576i). After uploading YouTube re-encode them to 480p. Can I restore correct interlaced resolution of this videos for further applying yadif deinterlace filter (may be in double framerate mode)? I found similar thread: https://forum.doom9.org/showthread.php?t=145301 , but it was closed. I tried to use lanczosresize(width,576,taps=6) and FixBlendIVTC filters but without result. Most effectively works filter linear blending deinterlace, but it very blurry video.

Original:

[Attachment 44341 - Click to enlarge]
Original+Applied YaDiF:

[Attachment 44342 - Click to enlarge]
Resized to 576+Applied YaDiF:

[Attachment 44343 - Click to enlarge]
Avisynth: lanczosresize(768,576,taps=6)+FixBlendIVTC():

[Attachment 44344 - Click to enlarge]
Avisynth:FixBlendIVTC()+lanczosresize(768,576,taps =6):

[Attachment 44345 - Click to enlarge]
Linear blending deinterlace:

[Attachment 44346 - Click to enlarge]

[johnmeyer]

Are you saying that it was YouTube that incorrectly re-sized interlaced video without first deinterlacing it?? I can't believe that would ever happen because there would be millions of massively screwed-up videos on YouTube if that were the case. I've never once seen this artifact on YouTube.

So, I'm not sure what you are asking.

If you are asking how to correctly re-size interlaced video, the answer is that you first deinterlace it, then re-size it, and then if you want to keep the video interlaced, you re-interlace it.

Here is one of many functions that you can use to re-size interlaced video, and end up with interlaced video:

function IResize(clip Clip, int NewWidth, int NewHeight) {
  Clip
  SeparateFields() 
  Shift=(GetParity() ? -0.25 : 0.25) * (Height()/Float(NewHeight/2)-1.0)
  E  = SelectEven().Spline36resize(NewWidth, NewHeight/2, 0,    Shift)
  O  = SelectOdd( ).Spline36resize(NewWidth, NewHeight/2, 0,   -Shift)
  Ec = SelectEven().Spline36Resize(NewWidth, NewHeight/2, 0,  2*Shift)
  Oc = SelectOdd( ).Spline36Resize(NewWidth, NewHeight/2, 0, -2*shift)
  Interleave(E, O)
  IsYV12() ? MergeChroma(Interleave(Ec, Oc)) : Last

  #Next line is optional
  #sharpen(0,.5) # Adjust 2nd value between 0.5 and 1.0 to taste

  Weave()
}

If instead you are asking how to un-do the horrible artifacts which result from re-sizing interlaced video without first deinterlacing, you might read this long thread over in the doom9.org forum. In this thread I was able (with help from StainlessS) to create a script which did a pretty decent job at removing the horrible "teeth" that resulted from this common mistake. If you go to the last page of those posts, you'll see that pretty much all the artifacts were removed.

You'll have to tune the script I present there in order to match your particular video.

Here is a link to the beginning of that long thread:

Repair Bad Deinterlacing

[LMotlow]

Looks like the O.P. ended up where he started, except for residual artifacts and degradation from the processing and obsolete lancsoz resizing. IS there supposed to be something magic about yadif's deinterlacing? I would have thought QTGMC would do a cleaner job on messy YouTube video. The "original" sure doesn't look blended to me -- more than likely YouTube took 576i, dropped alternate fields, and resized progressive video to 480p, which is what they usually do.

After spending some time considering what all this work was for and wondering if I read the O.P. correctly, all I can say is

[jagabo]

I've never once seen this artifact on YouTube.

I've seen it many times over years. Much less often with newer videos. I usually do something like Blur(0.0, 1.0).Sharpen(0.0,0.7).

[poisondeathray]

Did you try contacting the uploader / account holder?

YT stores the original video that was uploaded, but only the acct holder can access it (even if they deleted it locally, there is a copy on YT server). They might make it available for you depending on the details of the situation

[Lirk]

Are you saying that it was YouTube that incorrectly re-sized interlaced video without first deinterlacing it?

Yes. I guess this problem was due to the fact that some time ago YouTube didn't apply deinterlace filter before video resizing and perhaps some videos was uploaded without "interlaced" flag therefore deinterlace filter was not applied. Also this problem relates to not only YouTube videos. E.g. some resized interlaced TVRips without applied deinterlace.

Did you try contacting the uploader / account holder?

It's another question. Uploader does not want to give me a source.

And this problem relates to not only YouTube videos. E.g. some resized interlaced TVRips without applied deinterlace.

So I want to understand how to repair wrong resized (e.g. with lanczosresize) interlaced video.

[pandy]

So I want to understand how to repair wrong resized (e.g. with lanczosresize) interlaced video.

Rescale video to half of original size (source 576 then output 288) probably easiest way to restore (albeit vertical details reduced) proper video.
Yes, it is common to YT movies - lot of uploaders are unaware if they source is interlaced or not - they don't care and YT don't care either.
I would no expect from average consumer any knowledge about video technology.

[Lirk]

Rescale video to half of original size (source 576 then output 288) probably easiest way to restore (albeit vertical details reduced) proper video.
Yes, it is common to YT movies - lot of uploaders are unaware if they source is interlaced or not - they don't care and YT don't care either.
I would no expect from average consumer any knowledge about video technology.

Easest way - applying linear blending DI-Filter, but video becomes too blurry. Would like to restore video with minimal loss of sharpness.

[johnmeyer]

The link I already provided to you shows how to repair the large teeth artifacts. There is no way to actually reverse the original process.

[jagabo]

I agree with johnmeyer, there is no way to restore the original fields. The best you can do is blur the them together more and then sharpen a bit to restore sharpness in areas that weren't interlaced. What you'll be left with is something like a simple blend deinterlace of the original interlaced video. I gave one simple AviSynth method earlier. A more complex variation.

BilinearResize(width,288).nnedi3_rpow2(2, cshift="Spline36Resize", fwidth=width, fheight=height).Sharpen(0.0, 0.5)

Vary the downscale (288) to get the least residual combing, and the sharpen to get the sharpest result without oversharpening halos.

[Lirk]

I agree with johnmeyer, there is no way to restore the original fields. The best you can do is blur the them together more and then sharpen a bit to restore sharpness in areas that weren't interlaced. What you'll be left with is something like a simple blend deinterlace of the original interlaced video. I gave one simple AviSynth method earlier. A more complex variation.

BilinearResize(width,288).nnedi3_rpow2(2, cshift="Spline36Resize", fwidth=width, fheight=height).Sharpen(0.0, 0.5)

Vary the downscale (288) to get the least residual combing, and the sharpen to get the sharpest result without oversharpening halos.

Ok. Understand.