Dot Crawl Question

[hizzy7]

Hi Friends,

I was wondering if this is dot crawl or some other kind of artifact? I am having a hard time getting rid of it:

http://files.videohelp.com/u/183506/VTS_01_1.demuxed_2.m2v

Thanks!!

[jagabo]

Yes. Although they are a little unusual for PAL video. Most of the dot crawl filters work better with NTSC dot crawl's 2 frame pattern than with PAL video's 4 frame pattern.

Depending on how sharp the video is you can resize to half width then back to full width. That gets rid of most of it.

[hizzy7]

Hi Jagabo!

Re-size it how? With splineresize?

Thanks!

[jagabo]

Use whatever resizers you want

BicubicResize(width/2,height)
nnedi3_rpow2(2, cshift="Spline64Resize", fwidth=width*2, fheight=height)

[hizzy7]

Wow!! What is the principal behind this video magic??????

[jagabo]

Blur the little blocks away with the downsize, then upsize to restore the original size. Of course, if your starting with a sharp video it won't be as sharp after the downsize/upsize, and some small details will be lost. But if your video isn't very sharp (VHS, for example) it won't be noticed much.

[PuzZLeR]

If you'd like a little bit of sharpening, just add a line something like this, parameters to your taste, in your script

Sharpen(0.2,0.0)

You can put it right between the downsizing and upsizing. It can enhance the video somewhat.

Wow!! What is the principal behind this video magic??????

I too personally was stunned at how easy it was to greatly correct this problem when I first discovered it.

And I really don't get what's with all those boring scripts for it in other forums, or those filters for it. All useless, or if they "work" (somewhat) they create other worse artifacts.

And like one author who suggested "doing this only for the frames containing artifacts".

C'mon. Really.

[hizzy7]

Thank you Jagabo!

Here is some video from the film, which was recorded from tv.I don't think it is very sharp. There is a bit of ghosting in the clip. Do you think they are blended fields, an interlacing issue or a pal/ntsc issue?

http://files.videohelp.com/u/183506/LITTLE.demuxed.m2v

Thank you

[jagabo]

That is mostly progressive 25 fps. But in the middle of the clip something went wrong with the capture and pairs of fields from different film frames were woven together, chroma channels are screwed up, and some other problems are introduced. Later in the clip it straightens out again. I'd try something like:

Yadif(mode=1, order=1) # or QTGMC() or Interleave(TFM(field=1), TFM(field=0))
SRestore(frate=25)

If there are only a few sections with this problem I'd isolate them with trims or ReplaceFramesSimple().