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| Eyedunno |
| Posted: Dec 5 2012, 05:35 AM |
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Hello, this is my first time posting here, and my request (if it doesn't yet exist) is a little unusual, so please bear with me.
I like to capture old video games with a capture card, but there are serious issues with deinterlacing things that have a 60fps flicker. Using half fields will either show a static image of the thing that is flickering or show nothing at all. Using blended fields will show static, semi-transparent objects.
So I wondered, "what if you were to blend a frame with a 75% even/25% odd ratio, and the next frame with a 25% even/75% odd ratio, and so on?"
I did a little proof of concept, but first a little warning: I don't have a website and don't really feel like setting one up just for this, so I made a single HTML file with embedded base64 images, so it may take a minute or so to load, even on a fast connection. They are animated PNGs, so they will not show up properly in browsers other than Firefox or Opera. If you are using MSIE, Chrome, or Safari, sorry, nothing to see here. With that out of the way, here is the proof of concept:
http://www.dinkypage.com/161836
The important images are the first and last ones - the first one is a 60fps animation of what the flickering should look like, while the last one is my 30 fps proof of concept. Everything in between is the (inferior) 30fps alternatives. It seems to me that not only does the 75/25 method give the illusion of the same kind of flicker, but, although I haven't tested it further, it would most likely look pretty good with things in motion too - kind of like a compromise between even-or-odd-fields-only and blended fields.
So what I want to know is, is there a filter that deinterlaces with an algorithm like this? If not, does anybody have the chops to make one? It would seem to be a rather simple thing, and it would also seem to be a good middle ground between the two simplest deinterlacing methods that doesn't require much more processing power than regular blended fields.
Thanks. |
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| Eyedunno |
| Posted: Dec 6 2012, 01:39 PM |
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I kinda thought about this more, and maybe the best way to do it interface-wise is with a simple slider that would look kind of like this:
| CODE | top FIELD OPACITY ON bottom
field ODD-NUMBERED FRAMES field
|--------------|----------------------------------------|
25% 75% |
Even-numbered frames would have the opposite opacities, as described in my earlier post (so 75% top field/25% bottom field for the example above). 50%/50% would be the same as simply blending the fields equally. 0%/100% and 100%/0% would be fairly silly settings where top and bottom fields would alternate frame by frame. Anything in between would be kind of a compromise between the sharpness of discarding one field and the relative fluidity of motion of a blended clip, with 25%/75% and 75%/25% being probably the best for dealing with huge changes between the two fields (such as 60fps flickering, as mentioned in my other post). |
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| -vdub- |
| Posted: Dec 6 2012, 03:24 PM |
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Hard to tell with animation characters where they are made of square pixels. Any non animation very interlaced moving video to show this better ?
Somewhere put the word Blend as with your first post to describe this. |
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| Eyedunno |
| Posted: Dec 6 2012, 05:34 PM |
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I did try and make a short clip at home last night. But it's still only 23 frames long because I had to process each individual frame manually. It literally requires me to convert the interlaced source to 60 fps (with the duplicate field option), copy a frame from VirtualDub, paste into an image editor, copy the next frame from Virtualdub, paste it as a new layer, set opacity of the top layer to 75%, save the file, copy the next frame from VirtualDub, paste into the image editor, copy the next frame from Virtualdub, paste it as a new layer, set opacity of the top layer to 25%, save the next file, ............. That's why I think a filter would be nice!
Anyway, the other clip I made is also from a video game. And I do not understand what square pixels have to do with anything. The point is that:
Image 1) Has a fast flicker @ 60 fps
Images 2-4) Do not have a fast flicker @ 30 fps (completely static)
Image 5) Has a fast flicker at 30 fps, and looks reasonably like image 1! |
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| -vdub- |
| Posted: Dec 6 2012, 08:53 PM |
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Try asking the same on a relevant Doom9 forum where most in depth discussions for video technical take place. Post the same there with your examples people there will reply if your idea has been tried or if it is new. If new and seems possible someone will no doubt code an avisynth filter and maybe a virtualdub one. Either filter you could then use with virtualdub. |
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| GrofLuigi |
| Posted: Dec 6 2012, 10:33 PM |
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The description (without studying it deeper) reminds me of ConvertFPS (and I have used the filter only in simple modes). Anyway, it must be possible in Avisynth.
Edit: Another example would be PeculiarBlend (I think it doesn't apply here, but I wanted to show there is a filter for almost everything in Avisynth. 
GL
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| Eyedunno |
| Posted: Dec 7 2012, 02:26 AM |
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| QUOTE (-vdub- @ Dec 6 2012, 08:53 PM) | | Try asking the same on a relevant Doom9 forum where most in depth discussions for video technical take place. Post the same there with your examples people there will reply if your idea has been tried or if it is new. If new and seems possible someone will no doubt code an avisynth filter and maybe a virtualdub one. Either filter you could then use with virtualdub. |
Awesome! I will try it. Even if I have to use avisynth, I think I can deal with that, as right now, it is literally impossible to get the kind of all-purpose old-school video game deinterlacing I think I have hit on here. |
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| Eyedunno |
| Posted: Dec 7 2012, 02:35 AM |
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| QUOTE (GrofLuigi @ Dec 6 2012, 10:33 PM) | The description (without studying it deeper) reminds me of ConvertFPS (and I have used the filter only in simple modes). Anyway, it must be possible in Avisynth.
Edit: Another example would be PeculiarBlend (I think it doesn't apply here, but I wanted to show there is a filter for almost everything in Avisynth.
GL |
Yeah, it might have to be something to study further, because the thing is, I'm not really talking about converting the FPS. I had to do that for my examples, but that's only because no such filter exists to my knowledge so far. (Well, and converting interlaced video up to 60 FPS is the best way to deal with it in general, but YouTube, Facebook, and so on don't support 60fps video to my knowledge).
Really what I'm talking about is combining both fields of interlaced frames in an unusual way to get a result that looks much more faithful to the interlaced source under certain specific conditions, while also being pretty versatile for more general conditions. |
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| levicki |
| Posted: Jan 3 2013, 06:42 PM |
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Out of curiosity, did you try QTGMC deinterlacer?
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