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Jeff Bach
wondering how to capture video of a screen without the scrolling line moving down the screen
on Aug 6, 2013 at 6:15:57 pm

Hi all
Tried hunting through the forum but came up mt. I must be using the wrong keywords. I have a client who wants to do a short training video on how to setup an instrument. Instrument setup is done via a small touch screen display.

Their concern is that with an earlier video they did, there was a horizontal line moving down the screen. They want that horizontal moving line removed or never captured in the first place. If memory serves this is an issue with refresh rates or interlaced vs progressive, etc. I can't remember. But I am hopeful that this scrolling line problem is one that be solved.

Is there a way to capture video of a screen and not get that scrolling line? It's not a TV screen it is a small screen inside a large instrument.

If I can't solve it in camera is there a way to mask it out in AE or FCP????

Jeff Bach
Quietwater Films
Madison, WI.


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Mark Suszko
Re: wondering how to capture video of a screen without the scrolling line moving down the screen
on Aug 6, 2013 at 7:49:08 pm

The artifact you describe happens when the camera's frame rate does not match the refresh rate of an interlaced TV screen display on a cathode ray tube (CRT).

The standard fix is to use a camera that offers an adjustable shutter rate, what Sony calls "Clear Scan". You point the camera at the offending monitor and adjust a dial until the line disappears. Other camera makers call it by a different name, but it's a variable shutter.

This effect is only seen on interlaced displays, so if the equipment being demonstrated can use an LCD or Plasma screen, with progressive instead of interlace display, your problem won't happen.


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Jeff Bach
Re: wondering how to capture video of a screen without the scrolling line moving down the screen
on Aug 6, 2013 at 8:33:17 pm

I'm using an HVX200, so after reading your post I got out Barry Green's book and sure enough, there on page 121 is a description of Synchro Scan which reads just like Sony's Clear Scan. Hopefuly my bacon isn't cooked after all.

thanks for your response!


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Dave LaRonde
Re: wondering how to capture video of a screen without the scrolling line moving down the screen
on Aug 6, 2013 at 10:26:03 pm

If the client has upgraded to flat-screen monitors -- i.e. no video tubes -- it shouldn't be an issue. Five minutes at the client's place should make everyone rest easier; it's well worth it to do so for your own peace of mind.

Dave LaRonde
Former Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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