An odd case of bad deinterlacing

[cysjunk]

I've recently come across an episode of a show which seems to have been deinterlaced poorly in some way. I don't think it's been resized in any way however there are some very odd horizontal artifacts. It seems to be most noticeable on crossfades and the credits. I think there might also be some geometric distortion (see the BBC logo image). Is there any way I could correct this?

Crossfade
Credits

BBC logo
BBC logo from different episode

[johns0]

Doesn't look poorly deinterlaced,just a bad recording.

[cysjunk]

All other episodes of the show seem to be either still interlaced or properly deinterlaced so this must be some sort of deinterlacing/processing mistake. The show is mainly 25p however the transitions/credits are 50p.

[Alwyn]

Best to provide an untouched/unrecoded sample for analysis.

BTW, those two BBC logos are exactly 200x150 pixels; it looks like the same image twice.

[cysjunk]

Best to provide an untouched/unrecoded sample for analysis.

BTW, those two BBC logos are exactly 200x150 pixels; it looks like the same image twice.

If you look closer (i.e. the letter "C") you should be able to notice it.

Here are some samples clipped using VideoReDo:
https://files.videohelp.com/u/301835/Mongrels.S02E06.Kali.and.the.Psychological.Warfar...ABI%20(02).mkv (Opening scene with some crossfades)
https://files.videohelp.com/u/301835/Mongrels.S02E06.Kali.and.the.Psychological.Warfar....264-MZABI.mkv (End credits)

[jagabo]

It looks to me like the original video was progressive and logos/titles were overlaid as interlaced. Then the video was poorly deinterlaced. There's no fixing the scrolling credits. You can smooth out the BBC logos but why bother.

[cysjunk]

At the very least I want to see if I could smooth out the crossfades to remove the artifacts.

[jagabo]

Something like GradFun2DB(thr=3.0) helps with the banding without damaging other details too much. Higher values work better in the bright areas but mess up other details. Play around with the threshold. GradFun3() and variants might work better but it's not running on my computer right now.

[cysjunk]

I decided to do some quick tests using GradFun2DB and it does work on scenes where it's less noticeable such as the opening but on brighter scenes there seems to be nearly no difference whatsoever. Any higher than thr=5.0 and it starts to destroy the image. I'm sure there is something else that could tackle it since these are mainly just crossfades but I don't really use Avisynth that much so I'm unsure about what other filter/plugin to use.


These issues also seem to only be present on the US digital purchase version. I'm sure the UK digital purchase version of this episode fixes these issues but that's out of reach for me (those versions have a BBC logo at the start and appear to be slightly zoomed in but they don't have any artifacts unlike this one).

Edit: The same frame from the Hoopla release (this seems to be closer to the UK digital release however the quality is only 480p. The digital purchase versions are the only 1080p versions that are available for this episode). This is how it should look:

[jagabo]

It's hard to imagine how that banding can be accidental. Are you sure it's not intentional?

[cysjunk]

This is how the file looked when I downloaded it. I haven't done any additional processing to make it look like that nor do I even know how they could deinterlace it that bad. I'm sure it looks the same on the original source (this is an Amazon US WEB-DL).

[cysjunk]

A quick update: I've managed to mostly remove the artifacts in a test scene using my video editor and a few blending mode tricks as well as the lower quality version I had. That should leave just the credits sequence. The only other HD source I have for the credits is a 720p TVrip. I could use a delogo tool on that and then upscale it using AI I think.

Edit: Also a few transitions in one scene. See this image:

[Attachment 87796 - Click to enlarge]
I still have no idea how they could manage to deinterlace this as badly as they did. If anyone knows let me know.

[cysjunk]

[Attachment 87809 - Click to enlarge]

[Attachment 87810 - Click to enlarge]

I think I've finally made sense of what's going on. From what I can tell they seem to have applied a deinterlacing process that seems to cause both fields of the original 25i to blend together, resulting in these thick stripes on the video with this pattern:
Frame A
Frame A+B (think: A overlaid with 50% opacity over B)
Frame B
Frame A+B
Frame A
This pattern keeps repeating.
I can smooth out simple effects such as crossfades but like jagabo initially thought these transitions and the credits are destroyed. Unless anyone wants to rip the version from Amazon UK/iTunes UK I'm not sure if I'm going to be able to do anything else with this.

[jagabo]

You can create banding like that with simple resizers like those in VirtualDub that "interpolate only". Using AviSynth and the image you posted:

ImageSource("7fa68c34-9d99-4c2c-8189-7560759d8c00.png")

# Create an interlaced frame
p1 = Crop(0,60,768,432)
p2 = Crop(772,60,768,432)
Interleave(p1, p2)
SeparateFields()
SelectEvery(4,0,3)
#Spline36Resize(width, height*2)
Weave()

# downscale and upscale it
PointResize(width,200)
PointResize(width, height*2)

That's not exactly the same as your upscaled video but similar.


[Attachment 87811 - Click to enlarge]

[cysjunk]

I wonder how this version even managed to pass QC if manual processing like that code was required to get it to look like that. As for the blended stripes I have no idea.

[jagabo]

Most of that AviSynth script was to crop out the two original images and make an interlaced frame from them. All that's needed to create the bands is a resize interlaced video with a primitive algorithm. The first PointResize() created all the banding.

The fact that the damage is so obvious led me to speculate that it was intentional. Someone thought it looked cool.

[cysjunk]

I was thinking something similar as well. This show was niche and BBC Worldwide had already released season 2 on DVD in the UK with no extras or bonus features whatsoever (as well as no adjacent Blu-Ray unlike the first season). The US digital release is also missing the final episode of the series (S2E9). BBC Studios has treated it better since as the Hoopla release did have every episode (although Hoopla as a whole maxes out at 480p) however they haven't ever updated the US digital version. I suspect they didn't bother doing QC when it initially released. Two other episodes in the S2 US digital release are also interlaced flagged as progressive (which I don't mind as I can deinterlace in software).