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  1. New to the video world. I have a GoPro Hero5 with a gimbal and I'm testing it all out. I shot a video of me testing out the gimbal in 24fps as sunset (low light). After hours of editing footage in FCPX and reviewing the footage on YouTube, I feel like maybe I should've shot in 30fps? I'm learning FPS and how it affects video. I feel like the footage isn't as smooth as it could be. Btw, ISO was set to 400 max. Is this footage choppy? And should I've shot in 30-60fps with a higher ISO because I"m moving fast? Thanks. https://youtu.be/DA2rH0iY_U8
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  2. That video was converted from 30 fps to 24 fps by discarding every 5th frame. That creates several jerks per second in addition to the flicker/jerkiness inherent in 24 or 30 fps video. Shoot 60 fps if you want smooth video.

    Shoot with the exposure set as close to 1/fps as you can. Ie, if you shoot 30 fps try to set the exposure to 1/30. That will get you motion blur which helps reduce flicker.
    Last edited by jagabo; 20th Mar 2017 at 07:35.
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  3. Far too goddamn old now EddyH's Avatar
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    Heh, cute pup

    I wouldn't really call that "low" light, certainly not for a GoPro type camera, if it's worth the money paid for it. They should be quite good at least into dusk or from mid dawn. I'd certainly expect both my cheapie car dashcam and my phone's camera (it's a Galaxy S5 Mini, not really bought as a digicam replacement, I have a separate one and it scored poorly on that particular front) to work perfectly fine with default settings in the conditions on display here - the sun's still up and shining straight into the lens at times, after all! You should be able to get away with at least 30fps if not 60... also I wouldn't bet against the camera reporting that the video was recorded with ISO 400 being the maximum used/allowed, but actually having used a somewhat lower setting most of the time. A typical cheap digital stills camera could probably manage an exposure somewhere between 1/20 and 1/100s at ISO200 in those conditions depending whether in a fully sunlit position or deep shade, and even 1/20 is often enough for a "steady" image without any in-camera stabilisation if you don't have shaky hands (and are standing still!), let alone using a gimbal. For video, pushing that to 1/30s with a maximum of ... ISO 300? (I'm not entirely sure how to work THAT out), or an occasionally grainy or inter-frame-blurred 1/60s at upto ISO 400 (but mostly less) should look entirely fine and in fact easier on the eye than an absolutely temporally crisp version with no motion blurring at all (which is, e.g. why some of Michael Bay's Transformers action sequences are so utterly impossible to follow, as you lose all the subtle cues that let your eyes track the movements properly).

    That said, I played parts of the video back on both of my desk monitors, one of which has a 75hz refresh and the other 60 despite both being LCDs (I'm in a PAL region, so the slightly more 50fps and much more 25fps compatible scan rate is useful for playing regional footage smoothly, alongside NTSC stuff on the other), and it doesn't seem super-choppy on either of them. There's a little unevenness here and there, but it's no worse than I'd typically expect from youtube videos or a slapdash bit of portable camera conversion on a TV news bulletin. Really, 24fps should be avoided unless you have a good reason for using it (like you want the lower framerate effect and will only be showing the result on a Film-24 compatible hi-def display), and it won't really have gained you a great deal of extra light energy per frame (like 25%, so the rough equivalent of ISO 500 sensitivity whilst retaining ISO 400 grain) but it hasn't gone THAT badly here.


    If the light's really low and the camera supports it (I know *some* action cams do, and really if any would it should be GoPro), it might be worth investigating 20 or 15fps, so long as that actually bumps up the length of time the shutter is open for. The decimation from 60 (at 20), or 60/30fps (at 15) will be noticeably silent-movie-ish, but the inherent motion blur should help cover some of that up and make it more of a stylistic thing. You could probably up the resolution as well by doing that (e.g. to 4k instead of 1080p or whatever), and use a fairly soft resampling resize filter back down to HD or even SD resolution to ramp up the effective ISO and/or brightness by combining/averaging 4 (or 16~20) original pixels down into one.

    A maximum of 400 ISO seems really poor, btw. I would have thought the inherent temporal noise-averaging effect of video would mean it could be possible to get away with 800 or even 1600, to catch grainy but usable low-light footage that could later be processed into something slightly less gnarly, even if still shots would already show some degradation from 100 to 200 to 400... I've rescued a surprising amount from what initially looked like almost completely black videos before, with a combination of extreme level boosting and then pushing the noise reduction about as far as it could be taken. The result wasn't exactly pretty, but it did at least illustrate some of what was going on, and does mean that an initially sort-of-dark recording has a lot of scope for touching up before things get ugly.

    (on that front, I think there are some temporal smoothing filters that could also help reduce the overall noise level of non-moving parts of the footage by essentially applying multi-frame motion blur, and maybe a smaller amount to slower movements, whilst allowing fast motion to remain sharp and free of blur-trails albeit noisy - which shouldn't be as noticeable there - by not smoothing those parts... similar concept to motion detecting deinterlacers, or indeed MPEG compression itself... which would mean you could shoot at 30 or 60fps, even if that means the picture comes out a bit dark and needs to be level-corrected later, amplifying the grain already inherent at ISO400 sensitivity, as the more stationary parts that the eye can analyse at leisure will have smoother dynamics, and the actually noisy parts will be moving around quickly anyway...)

    Happy filming ^_^

    Oh, and just keep experimenting. See what happens at all the different framerates and/or resoltuions in the conditions you're likely to shoot, and indeed even if you mess with other settings like ISO, shutter speed (if you can divorce it much or at all from framerate), aperture (probably unlikely), EV correction (I actually have to crank it down a little for my dashcam...), etc. You may find that you get the perfect result with a combination you might otherwise have never considered.
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  4. Ah, how did you know that? I just checked and just the first few clips were 24fps so that is what it selected by default. The rest of it is actually 30fps. So... I guess i can't retroactively add frames back? i don't know how it works. Would redoing the project to 30 fps make any difference? And I guess I'd have to re-edit and start all over if I wanted to. Thanks for getting back.

    Originally Posted by jagabo View Post
    That video was converted from 30 fps to 24 fps by discarding every 5th frame. That creates several jerks per second in addition to the flicker/jerkiness inherent in 24 or 30 fps video. Shoot 60 fps if you want smooth video.

    Shoot with the exposure set as close to 1/fps as you can. Ie, if you shoot 30 fps try to set the exposure to 1/30. That will get you motion blur which helps reduce flicker.
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  5. Haha, thanks. Appreciate it. Thanks for the reply. So much helpful info in there. I'm only just learning and a lot of the youtube videos ive seen say to set it at 400iso. Im thinking that was in even lower light though. I should've at least selected 800. And you're right, it wasn't really 'low light". If you choose ProTune on the gorpo you can set a lot of the settings manually just like you would with a DSLR in manual mode. I just dont know how that translates to video, i.e. frame rate vs shuttter speed and what it all looks like. so ill do as you said and experiment. Thanks for the tips!

    Originally Posted by EddyH View Post
    Heh, cute pup

    I wouldn't really call that "low" light...
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  6. Originally Posted by jaebird82 View Post
    Originally Posted by jagabo View Post
    That video was converted from 30 fps to 24 fps by discarding every 5th frame.
    Ah, how did you know that?
    Stepping through the video frame by frame I could see that every 5th frame was missing -- ie, there was a jump in the motion. Also, at normal playback speed you can see the little jerks that creates.

    Originally Posted by jaebird82 View Post
    So... I guess i can't retroactively add frames back?
    There are techniques to do so but it's rather difficult. Attached is a segment of your upload where I inserted motion interpolated frames for the missing frames. I used AviSynth.
    Image Attached Files
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  7. I do see the difference. So that's what it would look like if i initially created the project at 30fps? It looks like i'll be redoing the entire project in my timeline only because I can use the practice anyway. Ill just create a new project and try and match my cuts from my previous one or maybe add different footage to switch things up. Thanks for your help.

    Originally Posted by jagabo View Post
    Originally Posted by jaebird82 View Post
    Originally Posted by jagabo View Post
    That video was converted from 30 fps to 24 fps by discarding every 5th frame.
    Ah, how did you know that?
    Stepping through the video frame by frame I could see that every 5th frame was missing -- ie, there was a jump in the motion. Also, at normal playback speed you can see the little jerks that creates.

    Originally Posted by jaebird82 View Post
    So... I guess i can't retroactively add frames back?
    There are techniques to do so but it's rather difficult. Attached is a segment of your upload where I inserted motion interpolated frames for the missing frames. I used AviSynth.
    Quote Quote  
  8. Originally Posted by jaebird82 View Post
    So that's what it would look like if i initially created the project at 30fps?
    Yes -- except for the distortions that motion interpolation sometimes creates. Step through the video and you'll see them, especially near the edges of the frame. See the bottom of frame 139, for example. Compare it to the frame before and the frame after.

    Image
    [Attachment 40997 - Click to enlarge]
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  9. Very interesting. You are really good at explaining things and dumbing things down without sounding too tehcnical btw. Thanks again.

    Originally Posted by jagabo View Post
    Originally Posted by jaebird82 View Post
    So that's what it would look like if i initially created the project at 30fps?
    Yes -- except for the distortions that motion interpolation sometimes creates. Step through the video and you'll see them, especially near the edges of the frame. See the bottom of frame 139, for example. Compare it to the frame before and the frame after.

    Image
    [Attachment 40997 - Click to enlarge]
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