Lens correction inconsistent after export?

Windows 10
Shotcut Version 21.03.21
MTS footage

Good day. When I apply the lens correction filter it looks good played in the editor, but when I export it is broken, the image is not consistent when it moves. I’ve experienced this for about a year now and started believing it was normal and that the filter should only be used in quiet footage, but recently seeing other’s tutorials where they use it made me realise I might be doing something wrong. This happens with both low and high-quality footage.

The image shows the filter the exported video. In the editor, it looks good.

I see some distractive visual tear in the screenshot of the exported footage, but I can’t judge this without seeing how it looks in the preview panel of shotcut. Right now, you only know how it looks in both, we have not seen both yet. Could you also upload the screenshot of the preview panel in shotcut at the same frame.

When you export, is Parallel Processing turned on or off? Try Off if you haven’t already.

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I could not add two images in the same post. This is somewhere in the same second. No tear in the editor.

I can not find where to turn it off. I found another thread where it said that not having that box meant I had the wrong bit version, 32 not 64. I do not know much about this, but I downloaded it from the website, where it said It was 64. Perhaps the button is in another place now? How can I check which one I have?

Yes, there is no tear.

Export > Advanced> Video > Parallel processing>Uncheck or disable
(Parallel processing is at the bottom of all settings in the Advanced> Video menu)

@UbitronicsUK has a nice video about finding shotcut version:-

This is what I see. I have the latest version.

Captura de Ecrã (167)

I have found in other thread that this button does not show up in slower computers, like mine. Is there any other setting I can change to make lens correction work?

I originally thought your version must be old to not have that option, but you mentioned you’re running 21.03.21, so that’s not it. I’m not sure what’s going on then. Can you upload a sample project with that one piece of media and filter settings for us to test?

Your screenshot doesn’t show the clip where you have placed the filter.
When you have a clip selected, it has a red border around it.

I think I might have figured something out. Is it not possible to apply lens correction to Interlaced videos? I use the “50i” setting on my camera due to battery life. When I export it as progressive the filter is working well, but according to what I searched around it says that exporting interlaced as progressive loses quality. These concepts are new to me, is there a way to still use the filter and not lose even more quality during export?

Most of the things about interlaced video was discussed in this topic,and I have not tested any interlaced videos, So I don’t know for sure:-

(Also, have you exported the video as interlaced or progressive?)

It should be possible to apply Lens Correction to interlaced footage. Interlacing in the worst case scenario would create artefacts that are one line of pixels offset. Interlacing should not cause the huge amount of shearing across multiple lines that your screenshots show.

When people say that exporting interlaced footage as progressive loses quality, they aren’t referring to visual quality of a single frame. They’re referring to time resolution. 50i slices time into 1/50th-second increments. Exporting it as 25p collapses two 1/50th slices into a single 1/25th slice, which loses the “time resolution” that 50i had. It essentially cuts the frame rate in half, which will change the perception of smoothness. This is the quality they’re referring to that gets lost. Whether the loss is significant to you is something you have to determine for yourself with trial and error. The alternative is to export 50i as 50p, and then you keep the 1/50th time resolution. But the file size gets larger. But not prohibitively larger, so 50p would be a good way to go if you want an easy button for highest quality.

This occurs because the image is interlaced and lines are changing vertical position (every other line belongs to a different field/time). The filter does not understand interlace and never will because that video plugin technology (frei0r) does not know whether the image it is being fed is interlaced or not. You can call it a bug, but I consider a limitation and will not be addressing it. Perhaps the engine will some day separate fields into discrete pictures and then recombine them at the end, but interlace in general is no longer much of a priority.
I think you do not see in the app preview because Settings > Progressive is turned on.

As a work-around, you can click the “Convert…” button, choose “Advanced” and check the “Deinterlace” option. This will convert your interlaced source to progressive. If you do this, let us know how it works for you.


Thank you everyone for the replies. Both converting individual clips to progressive and exporting the project as progressive works. These concepts are new to me so I didn’t quite understand everything but for my purposes I consider this fixed. Thanks again.