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Leecsjimmy
Leecsjimmy
Known Participant
February 10, 2017
Question

'Wavy' 4k video

  • February 10, 2017
  • 2 replies
  • 4334 views

Hi

I have taken a 4k video on my dji mavic pro.  After I do some.adjustments and output in 4k, I found that the video is somewhat 'wavy'. When the camera moves, it's like some parts of the preceding scene needs time to catch up...overlaying the previous scene.

Is that a export setting I should take note of? I output them in h264.

Jimmy

      This topic has been closed for replies.

      2 replies

      A
      Anonymous
      July 18, 2017

      Hi, I have the same kind of problem, uploading an example. What's going on here?https://we.tl/OeB7Mur7qT

      R Neil Haugen
      R Neil Haugen
      Legend
      July 18, 2017

      You're getting some 'rolling shutter' as you're camera is moving pretty fast past ... and close to ... moving subjects themselves. Slower flight of the drone would handle some of it, especially when flown that low.

      Fast panning is essentially what you're getting ... and it doesn't look good. Either go real slow, or so fast 'we' can't focus on anything.

      Also, there's a problem here with the nature of long-GOP images ... most of the 'frames' aren't actually recorded as frames, but only as data-sets of the pixels that have substantially moved since ... or before ... the previous or next "complete" i-frame. Some of the motion just isn't recorded properly. And this fast of a panning motion exacerbates the issue.

      Combing rolling shutter & long-GOP artifacting, you get what you see in your video. Which is actually no where near as bad as a couple drone generations earlier.

      Neil

      Everyone's mileage always varies ...
      D
      David Arbor
      Inspiring
      February 10, 2017

      It sounds like you're describing the rolling shutter effect, which occurs because of the way the sensor captures the image. The sensor records an image from the top down, not all at once. This means that if you have something moving very quickly in the frame or the camera itself moves too quickly you'll see a jello effect because the bottom of the frame is actually different than the top. Premiere has a Rolling Shutter Repair effect. Check out this video to see how it works: Rolling shutter repair in Premiere Pro

      If that's not it, can you post a sample of your video so we can see the problem?

      Leecsjimmy
      LeecsjimmyAuthor
      Known Participant
      February 11, 2017

      Thanks for the reply. I tried to Google 'jello effect' and mine doesn't look so serious.

      This is the link to the video : Mavic Pro - Marina Barrage - YouTube

      May not be so obvious here but on my TV it is very obvious, like a heat wave appearing on the video when the drone is moving.

      D
      David Arbor
      Inspiring
      February 11, 2017

      Hey Jimmy, you're right, it's not the rolling shutter effect; the camera's moving too slowly for that. I watched your video in 1440p though and I didn't see what you described in your first post. I did see some stutter in the shot when the camera moved, but that's not really what you were describing.

      After mentioning a "heat wave" I think I understand what you're seeing. It sounds like moiré, which is a pattern you see when lines are small and too close together. My guess is that you're only seeing it on the buildings or anything that's not natural, like the circular path surrounding the structure in the foreground. Moiré doesn't occur in nature because things aren't so symmetrical and evenly spaced. If this is what you're seeing it, can I also guess that you have a 1080p TV but a higher resolution monitor than that? Also, if you're seeing it in Premiere, is your Program monitor at 1/2 res and it's scaled down? What happens if you make the Program monitor full screen ("Ctrl+`" on Mac and PC) and you switch the playback to full res?

      There are things you can do to reduce moiré, like selectively blurring the image, but that would require masking and tracking. If you only see the problem at smaller resolutions and frame sizes, but not at full resolution, then the problem isn't in the footage, this is just what happens when you try to display a very tight pattern in a smaller area.

      If you're not seeing moiré can you post a screenshot of your Premiere program monitor where the problem is occurring; we can take it from there.

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