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Deinterlacing 1080i with hardware like the UpDownCross?

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Dan Swiney
Deinterlacing 1080i with hardware like the UpDownCross?
on Jul 26, 2012 at 12:54:12 am

My knowledge/understanding is a little weak in this area, I am hoping someone can correct any misconceptions I may have.

The problem:
I will have an HD-SDI 1080i (29.97fps) feed handed off to me.
I bring the signal in using a BM Ultrastudio 3D, thunderbolt.
I will be using Wirecast to encode and stream that signal at 1280x720.
There is de-interlacing within Wirecast as a software solution, but it boosts CPU use and doesn't do the best job.

Normally I use a 1080p or 720p workflow to eliminate this issue, but in this case I have to take what I am given.

The available gear:
BMUpDownCross, it can do a conversion, but is it deinterlacing?
Aja KiPro, which can convert 1080i to 720p but it is not de-interlacing?

My basic confusion seems to be, is a conversion from 1080i to 720p by definition also doing the deinterlace?


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Juan Salvo
Re: Deinterlacing 1080i with hardware like the UpDownCross?
on Jul 26, 2012 at 6:06:03 am

[Dan Swiney] "My basic confusion seems to be, is a conversion from 1080i to 720p by definition also doing the deinterlace?"
Yes. By definition a 720P (as in Progressive) signal cannot be interlaced.

That said what usually happens in cross conversion is each 1/59.94th field is scaled to it's own 1/59.94th frame in the 720P image. Combine both fields by quickly showing one frame after the other and you get a fluid looking image, like a 60i image. However each individual frame would have to be a progressive image. As that is what the format requires.

So to answer your question, any device properly converting to 720P is deinterlacing.

Colorist | Online Editor | Post Super | VFX Artist | BD Author

http://JuanSalvo.com


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