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NTSC aspect ratio appears differently in Edit and Color pages: why???

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Michael McCune
NTSC aspect ratio appears differently in Edit and Color pages: why???
on Jun 7, 2019 at 1:24:41 pm

An original DVD disk VOB file was transcoded by Media Encoder into a tif sequence for video editing. This tif sequence loads into Resolve and everything seems to work except that the Edit page and the Color page show different aspect ratios. For example, a face appears fatter in the Edit page viewer than in the Color page viewer.

I see that the image can be scaled in either the Edit page, (using the Transform Zoom controls), or on the Color page, (using the sizing controls for Input, Edit, Output, Reference, etc.). But any change made on either page, Edit or Color, using these controls is also reflected in the other page. This means that one can not match their aspect ratios using this method.

I am aware that NTSC, as a video format, has various options, mostly revolving around the standard 720x 486, some using square or non-square pixels and some with various dropped line configurations (such as dropping 8 lines down to 480 lines).

And I am aware that the Resolve Project Settings allow for various input and output Image Scaling options, such as cropped/not cropped, stretched, fit, etc. Tried them all.

I am aware also that the Edit page has a Dynamic Zoom option; it is disabled.

For test purposes, I created circles (the human eye is very good at seeing an out-of-round circle) in the Color page and also in Fusion. These show clearly that indeed the circles as they appear in the Edit page and the Color page are different: one is not round. but fixing it then distorts the circle as it appears on the other page. The Fusion circle remains undistorted.

Any thoughts??? Gotta be something simple but not obvious.

Thanks guys, Mike


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Joseph Owens
Re: NTSC aspect ratio appears differently in Edit and Color pages: why???
on Jun 7, 2019 at 10:13:53 pm

If it is a ripped DVD, then you likely have 720x480 and as likely also to have non-square pixels. Was the DVD formatted for 4x3 or anamorphic 16x9?

Scaling should not be ambiguous across the application. As it is, though, geometry is prone to be affected by about two dozen factors even within Resolve: Input sizing, node sizing, project settings, dynamic zooms, inspector settings, pixel squareness... it goes on and on.

jPO, CSI

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Michael McCune
Re: NTSC aspect ratio appears differently in Edit and Color pages: why???
on Jun 8, 2019 at 4:07:10 am

Thanks, Joseph. I like your expression, "... should not be ambiguous across the application."

Well, it does indeed seem to be, as you put it so well, "... ambiguous across the application."

That aspect ratio mismatch or ambiguity is exactly the problem. As mentioned in my original post, changes to scaling--using any of the several methods you mentioned, either on the edit page or on the color page--do indeed make the changes as expected. I have tried them all.

Changing the scaling in any of these ways is not the problem. The problem (as far as I understand the situation now) is that an adjustment also makes the corresponding adjustment in the other page, color or edit: thus the aspect ratio mismatch is not fixed.

Of course, this scaling change propagation ordinarily is exactly what one expects and wants, assuming that the viewing panes on the two pages match.

And they should match. But they don't.

I must be missing something but don't know what that is.

Thanks anyway.
Mike


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Michael Gissing
Re: NTSC aspect ratio appears differently in Edit and Color pages: why???
on Jun 8, 2019 at 4:24:36 am

In clip attributes it is advisable to first set the correct pixel aspect on the clip. Multiple clips with the same attributes can be selected and the attributes changed on all. I make sure those attributes are correct before editing. Chasing aspect on edit or color pages may not be necessary if you set those clip based attributes first.

That said you may have done that and you are reporting a bug. If so then I suggest you forward the bug to Blackmagic via their forum.


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