Video becomes jerky / juddery when applying filters

SC version 20.07.11 / 64 bit
windows 10
32 GB RAM, Thinkpad P50

I mixed some clips originally in 3200 x 1800 and 30 fps together, applied some filters (contrast, color grading, saturation, sharpening) and exported in Youtube settings, 1080p, 30 fps, didn’t change default settings. The film came out jerky as if the framerate didn’t fit at all.

I tried to reproduce the error without the filters, just reducing the size, and came out fine, no jerkyness.
Then i added the filters again, but results still were fine. The filters add a lot of load to the cpu, took 8 times longer to decode.
The orig. project took over 1 h to render (12 min. video), did some cuts, applied filters to the track and some extra filters to single clips on that track. Also added a music track. Dont know what could cause the problem?

P.S. just repeated the whole project rendering, payed attention to render settings - same result: very shaky, jerky. I recognized video mode is not set ( i think i set it to automatic?).

What fps properties does Shotcut show for the source footage?
Is it exactly 30.00000 fps?

You have at least one filter on the track header.
What do you mean “just reducing the size”?
What filters did you use? Settings of each filter?

You are using an outdated version of Shotcut.
Newest version is available here.

Source footage is definetly 30.000 fps, double checked with VLC.

Seems i solved it! I think the video mode was not set correctly. I had it set to automatic i guess, but i didn’t find a red dot mark next to any of the video modes. Not sure how SC reacts in that case. But i definetly set the export settings to 30 fps. What parameters have priority: video mode or fps-settings in export mode?
I recognized the new working video is only 2 sec. shorter of overall length of 11:49 --> 11:47.
Shouldn’t the difference be bigger when changing from 25fps to 30 fps???

Video Mode creates the “true” video. Export settings take the true video and stretch it as necessary to conform to any modified export settings.

That appears to be the difference between 29.976 and 30.000 fps.

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What does that exactly mean? The resulting video was always 30.000 fps as shown by VLC and SC.
Are the export settings the defintion of the final fps or not? How can you stretch fps? A video can only be 30 fps or not and connot be “stretched”?

I am still a bit confused…

Yes, export settings are the final say in video specs. If the Video Mode is 25fps but the export settings are 30fps, then Shotcut renders frames at 25fps then duplicates every 5th frame to pad up to 30fps. This has potential to create stutter.

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I think there should be a clear warning when export settings dont match with the video mode concerning fps. What happens if video mode is not set? In my first project there was no dot to indicate the setting.

Those are default profiles. Not seeing a dot could mean custom settings are in use. The best way to check the video mode is to click on the Output track header and look at Properties.

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Thanks, Austin, for your prompt answers! :slight_smile:
I recognized i still had other errors in the last rendering, probably resulting from changing or setting the video mode to 30 fps/1080p. I think the error was as following: I originally set the video mode to “automatic” as the original footage was 3200x1800 on 30 fps. I started with an image sequence from renders from Google earth. When you start with images instead of a video as the first object in your timeline than SC sets the videomode to 1080p/25 fps per default! When i later added clips in 30 fps this didn’t pay to the settings. As i work with proxies, these were also considered to be 25 fps. When i reused the old project and adjusted the video mode to 30 fps the old proxies didn’t fit any more. The same applies to filters and keyframes. That was the reason for mistakes in the 2nd rendering, where i discovered there were gaps at the end of each clip - so they didn’t fit together any more.
Now i am doing the 3rd rendering and it comes out as 11:49 again for 30 fps. The missing 2 sec were due to the artefacts in the proxies, resulting in small gaps. The videos always came out as 30 fps, but as you described rendering was internally done in 25 fps and then every frame duplicated, resulting in stuttering. Hope it will come out fine now - finally :slight_smile:

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Finally, here are the results after still some editing and still some imperfections left at the cutting points:

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Nice trick flying through the bridge!

Needs a lot of practice :slight_smile:

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