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artifact lines from HD videos on Youtube


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#1 Joel Balik

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Posted 26 January 2011 - 05:08 PM

How come some videos from all the cool HDSLR projects show these horizontal random quick artifacts and then the more professional style shoots don't? Is this a sort of camera motion bad motion effect? Can someone please explain how to avoid it, or is it because of Youtube's compression video algorithm and MP4?
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#2 John Sprung

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Posted 26 January 2011 - 08:25 PM

The one thing that's different about DSLR's is that they skip lines in video mode. That's because they can't process the full chip's worth of data fast enough for 24 FPS. The missing lines may be what's messing with the DCT compression in MPEG.





-- J.S.
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#3 Joel Balik

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Posted 26 January 2011 - 09:14 PM

you're referring to MP4 as well which is the Youtube format?
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#4 Gabe Spangler

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Posted 26 January 2011 - 09:25 PM

This is almost never the camera. I believe this might be the resizing that is necessary to display the video in a little window when not in full screen. I own a 7D and I never have the horizontal lines you speak of. And I know exactly what you are talking about. It's not the aliasing or moire. It's quick horizontal artifacting. And like I said, I think it only happens when you have to resize video.

Some people compress their video correctly for Vimeo, some do not. I don't believe it has anything to do with the original footage.
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#5 Joel Balik

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Posted 26 January 2011 - 09:32 PM

That's what I thought. I've noticed that this effect seems to happen during camera movements.
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