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slit scan? temporal displacement?

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markoc
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There is a "delaygrab" frei0r plugin, that does something similar, although you can not use a grayscale image to specify delay.

Making a "mixer" plugin, that would use one input as delay would be quite easy...
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In my opinion, the key question here is: do you want to reproduce the result or do you want to reproduce the technique? I would assume the former.

I think that the key to reproducing the result is already in the beginning of the second video you link to. All you need is a non-affine transformation, and to my limited knowledge, Kdenlive has a corners effect for this. You first need one or two clips which act as the scrolls. You may take a super wide slide (image) and slowly or quickly move the viewport across, the zoom and pan effect should help here. Next, slap some glow effect on it, if you like. Then add the corners effect (or whatever it is called). Deform your viewport such that it forms one half of your final result, like one half of an open window glass. Repeat this with the same or another clip, mirror it, so it complements the first clip. This should roughly reproduce the effect.

To my limited understanding, split screen was a technique for doing a certain kind of non-affine 2D transformation. Since optical lenses are limited in what transformations are possible with them, the film makers had to come up with other means to create more effects. With split screen, you use the temporal axis as a means to do some transformation. But you don't need to reproduce this in Kdenlive, as you have powerful 2D non-affine transformations at hand, so no need to emulate a mechanical-optical setup here.

The slit screen technique is a mechanical-optical rendering engine. Thus, we don't need to emulate the rendering engine, as modern NLVEs are much better at this task. All we need, is reproducing the outcomes of these mechanical-optical rendering engines. Unless we're interested in the engines themselves. But I understand the original poster needs the result, not the engine.

In the second video, this is also explained. The slit screen result can be comparably easily achieved, but it is difficult to emulate the technique in itself. If you watch through the explanation of how the mechanical setup is, you'll surely agree that it is a hassle ... even if you are emulating it in a computer instead of a mechanical setup. So just recreating the result should be much easier.

Hope, this helps.


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Re: slit scan? temporal displacement?

Thu Mar 06, 2014 10:55 am
delaygrab seems sort of it, but yeah, i want to be able to use gradients, and other arbitrary maps.

no, i don't want to build something in kdenlive that's a digital version of the lego slit-screen machine :D
i just want to click a few buttons and get those results 8)
User avatar TheDiveO
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As I said, the corners effect should get you what you want. Some more assembly required, as I outlined above, yet no need for a temporal filter or effect.

http://userbase.kde.org/Kdenlive/Manual ... rt/Corners


TheDiveO on YouTube: diving videos and aerial (quadcopter) videos, all made with Kdenlive.
TheDiveO Blog: know-how about Protune-grading in Kdenlive, GoPro HD Hero 3, DJI Phantom Quadcopter, full face mask diving, and some more...
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Thu Mar 06, 2014 4:36 pm
yeah, the "stargate effect" can be done with "corners"... but i'm not seeing a practical way to use the corners effects to do this kind of temporal displacement mapping - http://youtu.be/YCZ3MqXOfYQ?t=1m27s

come to think of it... shouldn't a "bump map" effect be part of kdenlive, too?
User avatar TheDiveO
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Oh, I see. Thanks for the tutorial link, learnt something new. It looks like this may be what you are locking for: http://userbase.kde.org/Kdenlive/Manual ... Delay_grab ... it uses a time delay bitmap.


TheDiveO on YouTube: diving videos and aerial (quadcopter) videos, all made with Kdenlive.
TheDiveO Blog: know-how about Protune-grading in Kdenlive, GoPro HD Hero 3, DJI Phantom Quadcopter, full face mask diving, and some more...
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Re: slit scan? temporal displacement?

Thu Mar 06, 2014 11:30 pm
seems like delaygrab has the engine that i'm after, but lacks the user-selected map inputs. it just has that one "vortex" style of map built-in, and that's it.
User avatar TheDiveO
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You can try to contact Dan Denedy of MLT fame. He often kindly helps. If you ask him he might update the plugin if time permits.


TheDiveO on YouTube: diving videos and aerial (quadcopter) videos, all made with Kdenlive.
TheDiveO Blog: know-how about Protune-grading in Kdenlive, GoPro HD Hero 3, DJI Phantom Quadcopter, full face mask diving, and some more...
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i'm not finding any contact info... maybe i should just file a feature-request in mantis...?
User avatar TheDiveO
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This first needs to be fixed upstream of Kdenlive in MLT. See here for online support: http://www.mltframework.org/bin/view/MLT/OnlineSupport

Only after MLT has been fixed to support a timr displacement bitmap, then Kdenlive can take over, adapting to the new functionality. Then you should file in Mantis. But only after MLT has moved and solved the upstream part.


TheDiveO on YouTube: diving videos and aerial (quadcopter) videos, all made with Kdenlive.
TheDiveO Blog: know-how about Protune-grading in Kdenlive, GoPro HD Hero 3, DJI Phantom Quadcopter, full face mask diving, and some more...

 
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