Is there a name for these vertical artifacts? Can they be filtered?

[LaserBones]

Is there a name for these vertical artifacts? I occasionally encounter these when encoding a DVD and don't understand what they are or how they occur. Is it an artifact from the transfer process? Can they be filtered?

[Quint]

I remember to have got these as a result of de-interlacing quite often. It seems that quite chaotic random structures get clustered by deinterlacing and become more visible. Maybe you could try different de-interlacers.

[LaserBones]

Thanks I just tried some other deinterlacers, QTGMC, BWDIF, yadif, but couldn't find a solution. Any other ideas? Surely there is a name for this as I've encountered it more than a few times.

[davexnet]

post a short clip from your source, something that shows the problem

[LaserBones]

post a short clip from your source, something that shows the problem

Clip attached

[davexnet]

post a short clip from your source, something that shows the problem

Clip attached

What is the source of this clip? I see it's mpeg-2, is it cut directly from the disk's VOB file?
Is it a commercial disk?

[LaserBones]

post a short clip from your source, something that shows the problem

Clip attached

What is the source of this clip? I see it's mpeg-2, is it cut directly from the disk's VOB file?
Is it a commercial disk?

yes. vob cut in avidemux. commercial disk. I've encountered this on DVDs for 80s-90s films.

[davexnet]

Ok. Looks like the field order is wrong, is this any better?

[LaserBones]

Ok. Looks like the field order is wrong, is this any better?

I got that. I'm referring to the vertical like noise. look at the whitewall in the back. its easy to see in the screenshot I posted above as well.

[davexnet]

I think it's just noisy, I don't think it's an artifact of the deinterlace - unless I'm still looking at the wrong thing.
Does this version with some denoise help?

[Sharc]

@LaserBones: Post a few seconds of the original .vob of the DVD
The .mkv looks like a messy PsF or poorly baserate deinterlaced video encoded as interlaced .... and there are mpeg2 artifacts.

[lollo]

As davexnet wrote, if you are referreing to the noise you can try something like TemporalDegrain2(degrainTR=3).



video comparison: comp.avi

image comparison: https://imgsli.com/MzAwMjUw

You could add some light sharpening after.

If you refer to the vertical clearer bar, it is in the source and difficult to remove.

[Sharc]

I understand the OP refers to these vertical patterns, present all over .... (enlarged x2).

[Attachment 82473 - Click to enlarge]

[Selur]

I agree it's not caused by deinterlacing, you can simply look at the separated fields to see the artifacts are already in the fields.

Looks to me like noise was badly compressed, so I would mainly categorize this as compression artifacts.

Cu Selur

Ps.: DPIR denoise might be useful with this.

[lollo]

Looks to me like noise was badly compressed, so I would mainly categorize this as compression artifacts.

A temporal denoise filtering attenuates the artifacts. It would be interesting to see the bitrate given to the mpeg2 encoder by the DVD producers, it is probably in the low range (or the video master was very very noisy)

[Quint]

I agree it's not caused by deinterlacing, you can simply look at the separated fields to see the artifacts are already in the fields.

Yes... but less visible. That was my point. I did not say, they were completely invisible on the fields... And I also did not say, that they were CAUSED by deinterlacing. Deinterlacing (or field-delay-correcting) clusters and increases the visibility. I had these very often, mostly with old recordings that were copied multiple times on multiple media, always with slight compression. So the original cause may be bad compressing in some state, that increased and clustered some noise, I agree to this.

[jagabo]

Something like:

edges = mt_edge(mode="hprewitt", thy1=50, thy2=50).Blur(1.0).Blur(1.0).ColorYUV(cont_y=500)
Overlay(BilinearResize(width/2, height).Spline36Resize(width, height), last, mask=edges)

[LaserBones]

Something like:

edges = mt_edge(mode="hprewitt", thy1=50, thy2=50).Blur(1.0).Blur(1.0).ColorYUV(cont_y=500)
Overlay(BilinearResize(width/2, height).Spline36Resize(width, height), last, mask=edges)

Hey Jagabo, This is amazing. If you have time, would you mind explaining what the edge mask is doing? I'm not familiar with edge masks. Other than that you're just halving the horizontal resolution to blur away the artifacts correct?

[jagabo]

Yes. mt_edge() returns a map of sharp edges. Where there are sharp edges the map is white, otherwise black. Overlay() is used to restore the sharp edges from the original video onto a horizontally blurred version of the video. The edge map is used as an transparency map. Here's a slightly modified version of the script:

LWLibavVideoSource("clip.mkv", cache=false, prefer_hw=2) 
vInverse() # blur away residual comb-like artifacts (time base errors, filtering errors)
edges = mt_edge(mode="hprewitt", thy1=50, thy2=50, chroma="-128").ColorYUV(cont_y=500).Blur(1.0).Blur(1.0)
Overlay(BilinearResize(width/2, height).Spline36Resize(width, height), last, mask=edges)

You can see the edge map by adding return(edges) to the end of the script:


[Attachment 82616 - Click to enlarge]