Hello all,
In about 6 weeks I will be leaving for a year long travelling expedition across the world and I've bought myself a dji osmo action 3 with a load of mounts, with the idea of filming some nice scenes. Since I am pretty new to filming/action cameras I have been reading a lot about the camera, filming techniques, recommended settings and video editing. My plan is to record many different kind of clips and in the end compile it into some sort of 'aftermovie' using Davinci Resolve. So there will be high action footage, like mountainbiking, motorbiking, etc and more relaxed footage like hiking, snorkling, landscapes, city scenery, etc.

So far I've decided I want to film most of it in 4k 30 fps, except for some scenes that I'd like to have in slow motion, which are recommended to be filmed in 60 fps / 120 fps. So this is where some questions started to arise. I know there is a slowmotion mode on the osmo action 3, with the option to go 4x or 8x. But I also know there is an option to drag your clips out in the video editor, creating a slowmotion effect that way.
Question 1. What is the difference between these 2 methods, and which is generally recommended for the best results / quality of life?
Question 2. If I'd use the osmo action 3 slowmotion mode, in how much fps is that filmed and can I safely choose 4k?

Then I've heard that your 'project' in the video editor can only have one fps value. Let's say I go for method 2. I would like to combine my 30 fps footage with the 60 fps clips to get those slowmotion sequences in there. I've read that with the video editor you can convert the 30 fps clips into 60 fps, and that it duplicates the frames so that it ends up as 60 fps. This way you could take the actual 60 fps footage and slow it down to your liking, making sure it looks smooth and not choppy. And the actual 30 fps footage will still look the same.
Question 3. Is this a correct understanding of the subject? Am I missing anything?
Question 4. Is it also an option to set the project as 30 fps (to scale down on cpu usage) and convert the 60 fps frames down to 30 while still looking smooth in slowmotion?

Question 5. Related to the fps topic, we have the 25 and 30 fps standards for household lighting, which differ based on county/continent. For USA and lots of south american countries it is 30 (NTSC) and for Europe and most of Asia it is 25 (PAL). Is it possible to get a good workaround for this, so that I can combine my footage shot in NTSC and PAL countries, or am I forced to make 2 seperate projects to avoid the light flickering? I know there is an 'anti-flicker' option on the osmo action 3 with the option of going 50hz or 60 hz. But for me nothing seems to work to remove this. I am in Netherlands and have my setting at 30 fps, and my indoor lighting keeps flickering on my footage, no matter if I pick 50hz or 60hz...  

Thanks in advance for the help. I have most of my other settings down, but this particular subject keeps confusing me and I don't want to end up with a load of useless clips.
Looking forward to your perspectives!

There are 2 ways to record slow motion on the Action 3. One, use regular video with 60, 100, 120, 200, or 240fps, or two, use the Slow Motion mode. Have you tried recording both and see what the difference is?

Bring both footage into QuickTime player (or something else that can show basic video info) and check out the FPS. What do you see?

The footage you record in Slow Motion mode will always have the frame rate of 30fps whether you recorded in 4x or 8x (1080p only).

The footage you recorded in normal video mode will show the frame rate you set it before recording (eg 60, 100, 120, 200, 240, etc). You can verify this in the movie inspector window.

Furthermore, in QuickTime player you can define the in and out points of the slow motion segment by adjusting the start/end points of the playback control. You can’t do that with footage recorded in Slow Motion mode (4x or 8x).

Record a normal video in 30fps, another in 120fps, and a third one in Slow Motion 4x mode. Create a 30fps timeline in you editor and put the 30fps normal video on the timeline. Let’s say you want to slow it down 4x (or 25% of its original rate). Notice the playback will be choppy because you don’t have enough frames to play back the video slower than it was recorded. So recording a normal video at 30fps and trying to slow it down is out of the question.

Now take the 120fps normal video, put it on the 30fps timeline and again stretch it so it will play back 4x as slow (or 25%). Notice how much smoother the playback is since the 120fps recording has 4 times as many frames in one second as a 30fps recording does.

Now take your 4x footage that you recorded in Slow Motion mode and put it on the 30fps timeline. Since videos recorded in Slow Motion mode have a 30fps playback rate, you don’t really need to do anything with it. It will automatically play back as you recorded it (4x or 25%) and will be smooth.

The added benefit of recording slow motion video in normal video mode using 60, 100, 120, 200, or 240fps is that you can choose how much you want to slow down the video. For example, recording in 4k gives you the max limit of 120fps. You can chose to play this back at the rate of 25% (4x as slow), or you can play it back at the rate of 50% (2x as slow), or don’t slow it down at all to play it back at regular 30fps speed. Of course you can slow it down at other percentages as well but these figures are multiples of your 30fps timeline so will play back super smooth.

So to summarize, if you want to create slow motion video, you should never record at 30fps and “convert” it to 60 or 120 or whatever rate because it will look like garbage. In other words, choppy.

If you want to be able to play around with various rates (eg slow down the video 25 or 50% (in 1080p you can slow it down to 8x or 12.5%), you should record in normal video mode using 60 or 120fps (provided you will be using a 30fps timeline). This way you can slow down a footage to 25% at some point and maybe to 50% at another.

If you don’t want to mess around with percentages and slowing down various segments, then just record using Slow Motion mode at 4x (or 8x in 1080p) and it will automatically play back at that rate on the timeline. But I’m sure you have tried all these already.

Keep in mind I am not an “editor”. I hate the editing process in general. I did play around with slomo a little so I am by no means an expert so I just gave you my amateur version of things.

Also, I noticed that when you record in Slow Motion mode, the bitrate will be about half of what a normal video usually is. So it will be lower quality. I have no idea why this is, and not even DJI support have an answer for it.

Regarding your NTSC/PAL and flickering issue, personally I don’t sweat it. I found that there are certain lights that will flicker regardless of your settings. I always shoot in 30fps, and set the frequency setting to “auto”. Most of the time I don’t film inside buildings and neither I walk around in the dark trying to capture street lights so I didn’t have much issue with flickering lights so far.


Good luck!