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Hoping this is the right place to ask this and that what Im asking isn't nonsense.

I record some top down videos of board games, the camera is on a boom arm fastened in place overhead pointing down (I can't work out a better way to do that at the moment but it works for now and isn't the main issue of this question anywho...), the boards in question have a white grid on them and when I edit and produce the footage I find afterwards that the lines seem to wobble, see here for an example of what I mean if you scroll to 6.47 (as a random point without things obscuring the view).

I'm wondering what the cause might be and if I can stop it happening.

I do have to use the distort tool in fcpx to drag out the edges and rotate things a bit as usually my camera is never centred on the board and so one end has a noticeable slant/narrowing to it as the camera is pointing at a slight angle, could that cause it and if so anyone have any tips or suggestions as to how I can ensure my camera is pointing square to the table? :/

Cheers!

  • That is an odd, trippy artifact! Is it only noticable on the YouTube upload? Or do you see it when previewing the export file? In the editor? On the source material? My initial thought is it is a compression artifact and if it wasn't perfectly square to the frame or you change coded settings, it wouldn't happen. But where in the chain it becomes noticable might hint at something else – Michael Liebman Mar 29 '18 at 21:49
  • No I see it even worse when viewing it in fcpx when editing (but I don't have optimized/proxy files when editing for space reasons) it does appear much less pronounced in the initial mov file I export from fcpx but then moreso once I've converted it in handbrake to a more manageable mp4 (but then it is dropping from 90gb to 250mb so maybe thats my problem 😓🤔) – MorkPork Mar 30 '18 at 7:01
  • Any time you increase compression or go through codec cycles, compression artifacts will get worse. You can try exporting directly to an mp4 to make it less noticable. But to prevent it entirely... What camera/recorder are you using? – Michael Liebman Mar 30 '18 at 15:39
  • Im using a pretty naff little camera, its high def but its just a panasonic hs60, which is small and compact enough for what we need/can afford. I had tried exporting directly to mp4 before but it takes soooo long from fcpx (6+ hours 😓) whereas exporting in mov first from fcpx then converting via handbrake was much quicker – MorkPork Mar 30 '18 at 18:08
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    It's not interlaced is it? Some early HD cameras shot 1080i, and this looks a lot like the ancient nemesis of thin horizontal lines, the interlacing artefact. You could try running it through a de-interlacer. – stib Mar 31 '18 at 10:57
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After much help above it looks like its because the camera I was recording on was recording in 50i but the project I had created in fcpx was set to 60p, this was causing issues with the final result as it tried to convert 50i to 60p...

I restarted one of the projects as 25p instead and copied in some of the source video again and a quick repeat of my normal output process (export as mov, use handbrake to convert to a reduced size mp4 for youtube upload) seems to give a much better result (I'm comparing the mp4 on my machine to youtube but there is 0 wobble and I don't think its youtube adding it in) so I think this is the solution, make sure your projects are set to the same fps as the source!

Thanks all

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