Idea for unusual deinterlacing method for retro games

Eyedunno · 15th December 2012, 17:13

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 already posted it on VirtualDub Forums, and they thought somebody here might be more knowledgeable about whether this exists and/or how to make a relevant Vdub or avisynth filter. So without further ado...

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.

A blended clip will generally blend the top and bottom fields with equal, 50%/50% opacities. But I wondered, "what if you were to blend a frame with a 75% top field/25% bottom field ratio, and the next frame with a 25% top/75% bottom ratio, and so on?"

I did a little proof of concept, but first a little warning: I don't have a website and didn'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 top-or-bottom-fields-only and blended fields.

Here's an example of the kind of interface that might work:

Code:

top                 FIELD OPACITY ON                bottom
field              ODD-NUMBERED FRAMES              field
|--------------|----------------------------------------|
      25%                         75%

Even-numbered frames would have the opposite opacities (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 from one frame to the next. 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).

So 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.

15th December 2012, 17:13	#1 \| Link
Eyedunno Registered User Join Date: Dec 2012 Posts: 7	Idea for unusual deinterlacing method for retro games 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 already posted it on VirtualDub Forums, and they thought somebody here might be more knowledgeable about whether this exists and/or how to make a relevant Vdub or avisynth filter. So without further ado... 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. A blended clip will generally blend the top and bottom fields with equal, 50%/50% opacities. But I wondered, "what if you were to blend a frame with a 75% top field/25% bottom field ratio, and the next frame with a 25% top/75% bottom ratio, and so on?" I did a little proof of concept, but first a little warning: I don't have a website and didn'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 top-or-bottom-fields-only and blended fields. Here's an example of the kind of interface that might work: Code: top FIELD OPACITY ON bottom field ODD-NUMBERED FRAMES field \|--------------\|----------------------------------------\| 25% 75% Even-numbered frames would have the opposite opacities (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 from one frame to the next. 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). So 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.