DVD: Shadow follows rapid movements.

[Ruut]

Recently I downloaded a DVD from the internet, which makes me wonder what's wrong with it.
These are 4 subsequent frames as shown by VirtualDubMod:







And this is what Gspot has to say about the VOB-file:



Can anyone tell me what's going on here?
And more importantly: Is there anyway to correct this?

[jagabo]

Recently I downloaded a DVD from the internet, which makes me wonder what's wrong with it. Can anyone tell me what's going on here?

Someone resized and converted a telecined NTSC video to PAL incorrectly.

And more importantly: Is there anyway to correct this?

No.

[Ruut]

Jagabo,

Thanks for your reaction.
I edoted my post after your reply.
Does that make any difference in your opinion?

[jagabo]

No, I was able to view your images by cutting and pasting the links that weren't working.

Someone who didn't know what they were doing took an telecined NTSC video and converted it to PAL. When resizing the frame from 720x480 to 720x576 they didn't account for the fact that many of the frames were interlaced. I can't tell from four still images but they probably didn't do a good job of the frame rate conversion either.

You could try running the video through a blend deinterlace which would reduce the comb artifacts but the frames would still look like double exposures. Your second image after a blend deinterlace:



There's one other possibility: maybe the mixing of the two fields was caused by the way you prepared your stills. But given their size, ~720x576, I think this isn't the case.

[lordsmurf]

How does it look on a tv set? The same?

[manono]

If possible, upload a 5-10 second untouched piece of the source, a piece with movement. We don't need any audio, just an M2V will do. You can use the [ and ] buttons of DGIndex to isolate and save a piece (File->Save Project and Demux Video). Upload to a 3rd party hosting site and post the link here.

[Ruut]

OK, thanks for all the help sofar!

Here is a 9 seconds sample:

http://www.mediafire.com/?m10gmjs30mm

Does that clarify the problem?

[jagabo]

Yes, it's as I originally guessed: incorrectly resized from a telecined NTSC video. There's not much you can do.

[manono]

Does that clarify the problem?

Sure does, and proves that jagabo was on the money when he says an improper resize was done on it. You have interlaced fields here, and that's never supposed to happen. And both fields of the interlaced frames are interlaced. This conversion was done by an incompetent moron. And this is a retail DVD, isn't it?

As he also said, you can deinterlace it to get rid of most the combing, but nothing will be able to get rid of the blends/ghosts/double images.

Oh, jagabo beat me to it. Nice work, deducing all that just from the pics.

[Ruut]

Thank you very much for your analysis, jagabo & manono: highly appreciated!

you can deinterlace it

Frankly: I have little experience editing VOB's (or MPEG-2). The fist thing I do with downloaded DVD's is convert them into XviD, using AutoGK, with excellent results most of the time. When I did that with this DVD the problem really was bad. That's why I'm back at the source (VOB's) right now.

So following your suggestion to try and deinterlace: can you adivse any tool that I could use to deinterlace the VOB's?

Thanks again!

[jagabo]

It was an easy deduction. The combing had a very distinct pattern of clear/fuzzy from top to bottom. A 2x nearest neighbor enlargement:



This is a sign that interlaced video was resized improperly. And since some of the frames had comb artifact and some didn't (and all four appeared to be frames where there was movement) it was obvious that NTSC telecined film was involved.

[manono]

So following your suggestion to try and deinterlace: can you adivse any tool that I could use to deinterlace the VOB's?

AutoGK uses KernelDeint to deinterlace, and that's an interpolating deinterlacer. You'll need to use a blend deinterlacer, like FieldDeinterlace, which is part of Decomb. You can't do it in AutoGK, but you can using GordianKnot as a front end, or by creating your own AviSynth script and manually encoding in VDub(Mod) or whatever.

Oh, so I was wrong about it being a retail DVD? It was downloaded? It's not scene stuff, so it must be P2P garbage.

[jagabo]

You can't do any kind of smart deinterlace because the two fields are no longer separate. All you can do is blur the two fields together (aka blend deinterlace) to reduce the comb artifacts -- at the cost of a blurier image, the frames looking like double exposures, and another round of MPEG compression artifacts.

It's not clear to me that the result will look any better than the original. If you're going to try this you might as well run a deblocking filter too. The video is full of macroblock artifacts.