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Outputting frame sequence but only every Nth frame

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Robert Newton
Outputting frame sequence but only every Nth frame
on Feb 8, 2019 at 8:13:32 pm

Hi,

I'm creating photogrammetry derived models from drone footage. The software I use to create the models works from frame sequences. Only it does not need the thousands of frames created when I spit out a frame sequence from AE based on the original video from the drone. I really only need around every 100th frame in that sequence.

I've worked out a very time-consuming, laborious way to get this done, but I keep thinking this has to be a simple render script in AE that tells AE to only render every 100th frame (Nth frame). Number sequencing is irrelevant to my software.

Any ideas would be helpful, thanks.
Robert



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Dave LaRonde
Re: Outputting frame sequence but only every Nth frame
on Feb 8, 2019 at 9:11:54 pm

It's going to be extremely helpful to know the frame rates of all the items involved: drone footage, comp, and what's needed for the next application.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Robert Newton
Re: Outputting frame sequence but only every Nth frame
on Feb 8, 2019 at 9:19:13 pm

Hi Dave, thanks for the response. Yes, clearly that would be helpful.

frame rate from drone footage = 23.976
frame rate from comp - 23.976

There is not a "frame rate" from the photogrammetry conversions software. It's not looking at a frame sequence, it's simply looking at a collection of photographs inside a folder. The names attached to those photos (i.e., sequence numbers) are completely irrelevant to the software. You can (and I do) combine still photos taken from ground level with frames from the drone. They can in fact be different resolutions and aspect ratios though it tends to perform better when all the frames share similar color grading.

Robert



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Dave LaRonde
Re: Outputting frame sequence but only every Nth frame
on Feb 8, 2019 at 9:55:57 pm

Good news -- this should be comparatively straightforward.
Your footage has all the frames you need, and then some! You can fix that in the comp.
Drag the footage onto the make comp icon at the bottom of the project pane. AE makes a comp in the footage's frame rate and its duration.

But you only need every 100th frame, so you change the comp's frame rate. Let AE do the arithmetic.
Open the comp settings (Cmd-k Mac, Ctl-k Win). Highlight the frame rate, move the cursor to the far right, and add the following: "/100"...... no quote marks. The frame rate then becomes 0.23976.

You can now render out an image sequence of each 100th frame in the footage for use in the next application.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Robert Newton
Re: Outputting frame sequence but only every Nth frame
on Feb 8, 2019 at 10:25:33 pm

Holy Creative Cow, that's brilliant! Of course.

Thanks so much Dave!



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Tomas Bumbulevičius
Re: Outputting frame sequence but only every Nth frame
on Feb 10, 2019 at 11:55:13 am

On a different note, assuming that this is a repetitive task of exporting, and footage of drone is with constant frame rate.

If you render output in AE's Render Queue, just create a 'Render Settings' profile which reflects Nth frame requirements.

You won't require to constantly change source comp settings - just choosing profile before exporting would do the trick.

Find out more:
After Effects Tutorials: motion design, expressions, scripting.


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