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Jittery 24p footage on GH4... set to 29.97?

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Travis Roesler
Jittery 24p footage on GH4... set to 29.97?
on Jan 20, 2017 at 1:35:26 am
Last Edited By Travis Roesler on Jan 20, 2017 at 1:47:45 am

Hey guys,

I recently filmed a ton of footage that turned out to have a strobe like effect on the GH4. It was all reasonably slow movement, it's not like I was panning super fast. I originally assumed that it was a shutter speed issue, although I never actually changed anything out of the box... so the preset should have had me covered.

However, it turns out that a ton of people are having jittery 4k footage, and one of them said that the problem was solved by simply using 29.97 frame rate...

I think it's all a little odd... I was in the Cinema D settings, in which only 24 p was available... and have now switched to 29.97 in the NTSC settings. I'm hoping that this helps with playback.

I'm using a ridiculously powerful mac pro... so it's not the computer. I'm using VLC and premiere, so it's not the code.

Why do you guys think that this Cine-like D and 24p footage is coming out crappy and strobey? I feel like i'm about to have a seizure!


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Sam Lee
Re: Jittery 24p footage on GH4... set to 29.97?
on Jan 25, 2017 at 3:56:55 pm

It depends on what your content is about. If it is non-dramatic and unscripted (docs, events, sports) are perfect examples), I always use 29.97P or 60P. 23.976 or 24P are more for scripted or planned shoot where you can control your camera movement and reduce the jitter. It is not a good thing to shoot in 29.97 and down convert it to 23.976 in editing. I had to learn the hard way when my content was submitted to Netflix for qc approval and it was rejected. Keep everything in the same frame rate (don't mix and match 24, 25, 29.97, 60p) with the exception of 120-240fps+ where you can slow down to your timeline's.


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Travis Roesler
Re: Jittery 24p footage on GH4... set to 29.97?
on Jan 25, 2017 at 4:03:47 pm

That's interesting about netflix... I always assumed that I would be fine exporting in 24p with perhaps the occasional frame discrepancy.

I should have shot it in 29.97 but I wasn't on the NTSC format, so it wasn't an option. I was brand new to the camera, and didn't know that i had to switch frequencies to unlock different frame rates, so I just said 'screw it' and banged it out in 24p.

It was actually a 'how to' series on butchering deer... which I didn't think had enough movement to create a noticible strobe effect. I also should have checked out the shutter speed, but figured it would have been fine considering I was just using presets.

In any event, I suppose now it's time to find the filter in AE which will allow me to fix this!


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Sam Lee
Re: Jittery 24p footage on GH4... set to 29.97?
on Jan 25, 2017 at 5:24:26 pm

If you ever plan to produce or provide content for either Amazon or Netflix, all of your editing frame rates and video quality must be up to the highest standards. Any visible video artifacts (compression is one of the most common) will be denied. One time I submitted a content with mixed 23.976 and 29.97 and it was rejected. The ratio was 60% 23.976p and 40% 29.97p. Interlace and progressive scan must be also correctly treated as well. Best to keep all progressive or interlace. Don't mix here and there. It's very tough and unpleasant. But you have to comply. From this experience, frame rate consistency is the utmost importance (one of the fundamental qc parameters). They may let you get away with 5-10 seconds max for the entire episode. Their $100K+ automated qc system will detect any cadence pattern changes and so forth. Plus about 200 other potential video flaws - such as color banding (arising from UHD-HD downconversion), ghosting artifacts, field dominance error, etc...

So for anyone who thinks they can get away with subpar highly compressed DJI Osmo, h.264 dSLRs, mixing frame rates or any way to save costs - 90% likely the content will not make it. Got to do it right and up to specs.


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Travis Roesler
Re: Jittery 24p footage on GH4... set to 29.97?
on Jan 25, 2017 at 6:26:20 pm

I bought that osmo and wanted to throw it out the damn window! Omg, that thing was terrible. Nice Gimbal, but loud fan, no battery life, difficult to set down... terrible. Anyhow...

Out of curiosity, what were you using to compress your videos? (program and cpu power?) I'm wondering if a higher quality compression would have eliminated any such artifacts.


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Sam Lee
Re: Jittery 24p footage on GH4... set to 29.97?
on Jan 25, 2017 at 7:57:33 pm
Last Edited By Sam Lee on Feb 1, 2017 at 2:20:33 pm

The DJI Osmo definitely has visible color banding and dithering artifacts for certain scenarios. I shot a POV scene driving scene with plenty of detailed trees, road and other fine details. When it goes to partially shaded area, the dithering artifact appears. This clearly is the result of the camera's compression. Last time I checked it was only 60 Mbps@UHD resolution. Just not enough to record the fine details. I paid dearly for the unusable footage and spent thousands more to reshoot properly in RAW. [Talk about sweet bit rate revenge!]



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Harold Dongle
Re: Jittery 24p footage on GH4... set to 29.97?
on Feb 11, 2017 at 6:50:43 pm

Were you panning handheld or on a tripod? What lens were you shooting with?

I think I saw a post where people were saying the Panasonic 35-100 f2.8 image stabilization could give you a jittery effect when shooting handheld, but I don't remember it sounding as pronounced as your strobing. Something to consider other than the encode, though. That thread advised making sure your firmware was up to date.

What was the out-of-the-box shutter speed you shot at? Any chance that the lighting for deer butchering + default shutter speed could have done it? I know some light can strobe but I thought it was only an issue at really high framerates.


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Tim Kline
Re: Jittery 24p footage on GH4... set to 29.97?
on Apr 19, 2017 at 2:43:40 pm

I have never personally came across that with the Gh4. Although any pans we do are very slow and usually use slider shots.
I would try the 24fps with a variable frame rate of 48. When you bring the footage into premier, right click your footage in the media bin and interpreter it as 24. Works everytime and will get super smooth shots.

Timothy Kline
Production Manager
Hilo Motion Pictures
Website:  https://hilomotionpictures.com


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Paul Vernon
Re: Jittery 24p footage on GH4... set to 29.97?
on Mar 31, 2018 at 10:17:30 am

Hey
Was a solution ever discovered for jerky panning on the GH4? I have tried nearly all settings / combinations of settings in an attempt to get that perfect build smooth pan.
I have more tests to complete but I am actually finding that by resetting my camera from PAL to NTSC and filming at 29.97 or 59.94 is producing the best results.
I can pan and follow a subject with little or no problems but it is when panning a nice wide landscape shot - even with a motorised pan like the Syrp Mini Genie - that I really notice the jitter.
Thanks
Paul


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Travis Roesler
Re: Jittery 24p footage on GH4... set to 29.97?
on Apr 2, 2018 at 3:38:29 pm

Hey Paul,

It seems like you have a very different use case than me, but my problem was solved by shifting away from 'face recognition' focus entirely.

The problem was that the GH4 tries to recognize where a face is GOING, to keep up with the subject... but that makes the thing go haywire with little slight changes in direction.

I switched back to 'choose a part of the frame to focus on by selecting a bunch of specific squares' mode, and just widened the field to include more squares that I was likely to be in.

Camera still sucks for any kind of movement related stuff... in my opinion.


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Paul Vernon
Re: Jittery 24p footage on GH4... set to 29.97?
on Apr 2, 2018 at 4:05:18 pm

Thanks for the message...... I always keep my settings on MANUAL focus, so its not a focus issue.


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Travis Roesler
Re: Jittery 24p footage on GH4... set to 29.97?
on Apr 2, 2018 at 4:17:12 pm

Ah forgive me, I thought this was a different post of mine. Deleting previous comment.


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