Re: RenderInfo scale factors are lying - FCPX only
Re: RenderInfo scale factors are lying - FCPX only
- Subject: Re: RenderInfo scale factors are lying - FCPX only
- From: Nathan Weston <email@hidden>
- Date: Thu, 09 May 2013 07:56:49 -0400
On 05/09/2013 12:06 AM, Paul Miller wrote:
On 5/8/2013 6:40 PM, Darrin Cardani wrote:
On May 7, 2013, at 3:57 PM, Paul Miller <email@hidden> wrote:
On 5/7/2013 5:37 PM, Darrin Cardani wrote:
On May 7, 2013, at 6:55 AM, Paul Miller <email@hidden> wrote:
Here's a really frustrating one.
In FCPX, I'm working on a 1920x1080 clip, using TEXTURE mode, and
for some reason the scale factors are both 1.5. What is the reason
for this?
Typically I would look at the output image size and use the scale
factors to determine the full image size, but in this case the
scale factors are clearly wrong.
Is there another way around this?
Usually I see this when the input is something like 720 (1280x720)
being scaled up to fit within 1080 (1920x1080). Is your input the
same size as the Motion Effect was created at? If not, then the
scaling is likely correct. If so, then it sounds like a bug.
Ahhhh - that explains it. The media is 1080P but the motion template
was made at 720P.
But - how is this information useful? I need to know the full media
size in FCPX. In this case, the input/output images are at the full
media size (since FCPX doesn't seem to be doing any down-sampling).
But the scale factors indicate the media should actually be 50%
larger, which isn't true.
Well, it has to do with what our designers think users will expect
when using the app. If you apply a blur set to some value (say 5) to
an image in an SD project it gives you a certain look. If you have the
same footage in HD, a user will likely want the same parameter value
to give the same look. So a value of "5" should look "as blurry" in HD
as it does in SD. Using the scale information we provide, that should
happen.
Does that make sense?
We've run into this as well. IMO it doesn't make sense and is a bug. The
render scale should indicate the scale factor between the original
footage and the input/output images.
Yes, but I'm already doing that myself in my plugin logic, since my blur
values aren't in pixels - they are in "image units", which I can derive
accurately if I know the image size and downsample factors.
Maybe there is another way to determine the proper original media size?
In Motion (and other hosts), this is usually (image_size / scale_size),
but not in FCPX.
We worked around this by clamping the scale factors at 1. Scales less
than 1 usually seem to be correct and indicate downsampling. Scales
greater than 1 are always bogus, and when they occur the real scale
factor is always 1.
--
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Nathan Weston email@hidden
GenArts, Inc. Tel: 617-492-2888
955 Mass. Ave Fax: 617-492-2852
Cambridge, MA 02139 USA www.genarts.com
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