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Old 4th January 2011, 21:57   #1  |  Link
OvejaNegra
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Restore bad deinterlaced videos

My father has a collection of videos in AVI+divx format. Those were shot with a DVcamera and converted to AVI with a tool that i don't know and with processing that i dont know.

I havent seen any of those videos yet, but according to my father descriptions, most of them have one of these problems:

a) The video has ghosting on the edges when moving, like a bobed video of 60 fps converted to 29.97 by blending the frames on avisynth.

Can that be undone? It's possible to recreate (not accurately offcourse) the 60 frames by detecting the direction of the movement and separating the moving pixels on 2 differents frames with a small offset? Or something like that.

b) the video was resized without deinterlacing first. Some videos has 800X600, others 720X540, others 512X384, etc. All of them present interlacing artifacts. Due to the resizing, using a dinterlacer does not works. I told my father to resize those videos in avisynth to 720X480 and 640X480, but after that, using a deinterlacer does not works yet. Maybe the videos were cropped before resizing.

I'ts possible to resize the videos to the original resolution? And after that apply a deinterlacer to get the deinterlaced frames?

If the videos were cropped before the resizing, its posible to detect the correct resolution and add the black bars to put the lines in position for a deinterlacer?

I don care if i have to do trial-error tests. This week end i'm going to my father house and i will spend all day trying to fix and convert the videos to DVD or something else.

thanks for the help and sorry for my english.
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Old 5th January 2011, 12:55   #2  |  Link
aegisofrime
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QTGMC(QuickTGMC) has a mode specially for processing badly deinterlaced videos:

Code:
QTGMC(InputType=2)
It might be worth giving it a shot.
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Old 5th January 2011, 15:38   #3  |  Link
Ghitulescu
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I assume the original DV tapes are no longer available
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Old 5th January 2011, 16:05   #4  |  Link
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Fixing an interlaced video that's been resized progressively is one of those problems that you'd expect someone to have solved, but they haven't. It gets asked here quite often. Stephen R. Savage's advice is correct.

However, some of the resolutions you listed are larger than the original. In that case, if the resizing was very dumb and the subsequent encoding was high quality, it might just be possible to recover the original fields.

You're going to have to post some samples to know for sure!

Always. Keep. The. Original.

cheers,
David.
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Old 5th January 2011, 19:21   #5  |  Link
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Thanks for the answers, i don't know yet if i will have access to the original tapes, righ now the only sure thing is the compressed files.

"Always. Keep. The. Original." <-------- tottally agree with you

"It is possible to reverse an upscale if you know the algorithm used."
Well, maybe a few trial-error using the different resizers on avisynth will give possitve results. Sadly i cant be sure if the videos are cropped before resizing, that will complicate everything.

I'll post a sample when i have access to the videos. Thanks.

Sthepen: Even if i cant recover the original lines and deinterlace is possible to remove or mitigate the uggly bands and wavy edges of a resized-interlaced video?
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Old 6th January 2011, 00:13   #6  |  Link
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I have plenty files like this- all coming mainly from editors, who have no clue what interlaced source looks like. This is a nightmare- FCP is usually main reason, but also AVID users quite often do the same.
This is very poor, lack of basic knowledge- there are so many people, who buys FCP and think they can make Hollywood movies
Also Apple and AVID should stop saying that you can mix resolution and file types!

Try:

QTGMC(InputType=2 or 3)

it won't resolve problem, but will clean some artefacts (at least did in my case).

Andrew

Last edited by kolak; 6th January 2011 at 00:17.
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Old 6th January 2011, 00:40   #7  |  Link
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@OvejaNegra:

With the exception of nearest-neighbor, applying the same resizer in the reverse direction does not give you the original. With most resizers, which are implemented as matrix algorithms, you would need to compute the inverse function. This may or may not need to be done once for every line/column of every frame.

As for the ugly bands in resized interlaced video, the best you can do is to resize to one half the original vertical resolution, probably with GaussResize, which should get you an even blended frame. You will not be able to separate the fields. If the video was only poorly deinterlaced and not resized, you can drop half the fields and re-interpolate them like kolak describes above.

Last edited by Stephen R. Savage; 6th January 2011 at 00:44.
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Old 6th January 2011, 12:17   #8  |  Link
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Quote:
Originally Posted by Stephen R. Savage View Post
As for the ugly bands in resized interlaced video, the best you can do is to resize to one half the original vertical resolution, probably with GaussResize, which should get you an even blended frame.
...but this won't work if the video has been pointresized down first. The resulting aliasing of the original interlacing can't be removed - it can be 5 or 10 lines high!

Cheers,
David.
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Old 6th January 2011, 14:41   #9  |  Link
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Perfect! thanks to everyone for the help!

If possible i will recover the original tapes.
As last advice, can anyone recommend me a DV capture program that gives me good control of the capture process?
Thanks
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Old 6th January 2011, 17:10   #10  |  Link
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Old 6th January 2011, 23:18   #11  |  Link
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Perfect! thanks!
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