Grass abruptly changes texture/brightness: Compression artifact?

Jeremy Stanley · May 15, 2017

Today I tried out the ActiveTrack feature of my new Mavic Pro, and I'm very happy with the tracking, but there's a distracting artifact with the grass. It seems to abruptly change texture/brightness several times per second.

This was shot at 4K/30. I've already discovered that 1080p60 is unusable due to moire effects.

Is this the sort of artifact people suggest shooting at 2.7K to resolve? Or would getting a set of ND filters help for this, by allowing individual frames to have some motion blur? (Instead of being a sequence of pin-sharp 1/1000-second exposures.)

JoostGT3 · May 16, 2017

It may have to do with the codec as well. Mavic renders the movies with the h264 codec. As I understood it, this codec only stores fully rendered images every 8 or so frames (p-frames). The frames in between are just rendered as measured alterations from the previous fram (i-frames). When you have scenes that have lots of fine detail in them that change rapidly, you get this kind of movies. I'm not sure if my explanation is entirely correct, and I'm also not sure whether there is a solution. If there is, I haven't found it yet!

mw174620 · May 16, 2017

You could try using 24fps, which will help slightly and give more of a cinematic feel.

Also, you could lower the shutter speed. That seems a little fast from my experience.