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Panasonic GH4 jitters strobe effect when panning


hdd

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Hi, i was wondering if anyone is having problems with jitters on the GH4.  I am testing the camera with a 50mm manual Nikon lens and any small movement or panning creates a significant jitter, strobe effect.  I am using 4k at 24p and can't figure out if i am doing something wrong.  If i compare the footage to my Sony FS100 the difference is really noticeable.  I am getting ready to return the camera...  

 

Any feedback greatly appreciated.  Thanks.

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It's called judder.  I have seen a couple clips with this being a problem, but most are fine.  There were also reports of this on the GH3 from time to time.  Proper camera use and settings (shutter angle, panning speed, frame rate) can reduce this.  Are you encoding to 100 Mbps?

 

@Darwich, did you mean the shutter angle too high or too low?  Increasing shutter angle should smooth (blur) the panning.

 

Here is a link that may help.

 

http://www.red.com/learn/red-101/camera-panning-speed

 

Michael

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Hi, i was wondering if anyone is having problems with jitters on the GH4.  I am testing the camera with a 50mm manual Nikon lens and any small movement or panning creates a significant jitter, strobe effect.  I am using 4k at 24p and can't figure out if i am doing something wrong.  If i compare the footage to my Sony FS100 the difference is really noticeable.  I am getting ready to return the camera...  

 

Any feedback greatly appreciated.  Thanks.

Hi hdd,

I also had major problems with my GH4. An unbelievable amount of strobing when shooting 24p, 25p and 30p in 4K or C4K.
I've tried all the possible settings/combinations! Different Hertz, high or low shutter speed, shutter speed angle mode, shutter at 48 with synchro scan and nothing seems to work. (when lowering the shutter, it only got more ''useless'' blur ofcourse)
Even filming with a Steadicam doesn't improve the image at all.
I'm always filming in 1080P 24P NTSC with my Canon 650D because I really like the subtle cinematic ''stutter''-look of 24P, but on the GH4 it's at least 4 times more present, simply way to much for professional use!!.. So I returned my GH4 last week :(..
Check out my C4K footage (directly from the camera) here: 
https://www.wetransfer.com/downloads/3445dbee96a8edd4b8c4bb2eb37e8c9d20140709233049/85d284b92f4d6516154757236559385d20140709233049/a06e27

Cheers

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Hi hdd,

I also had major problems with my GH4. An unbelievable amount of strobing when shooting 24p, 25p and 30p in 4K or C4K.
I've tried all the possible settings/combinations! Different Hertz, high or low shutter speed, shutter speed angle mode, shutter at 48 with synchro scan and nothing seems to work. (when lowering the shutter, it only got more ''useless'' blur ofcourse)
Even filming with a Steadicam doesn't improve the image at all.
I'm always filming in 1080P 24P NTSC with my Canon 650D because I really like the subtle cinematic ''stutter''-look of 24P, but on the GH4 it's at least 4 times more present, simply way to much for professional use!!.. So I returned my GH4 last week :(..
Check out my C4K footage (directly from the camera) here: 
https://www.wetransfer.com/downloads/3445dbee96a8edd4b8c4bb2eb37e8c9d20140709233049/85d284b92f4d6516154757236559385d20140709233049/a06e27

Cheers

There isn't much panning in your shot and hence not much there to cause juddering.  When I play that clip on a Premiere timeline, it seems just fine to me - and I happen to be one of those guys who dislikes judder and have been critical of the look given by 24fps that so many film makers seem so happy with.  I find it distracting.

My guess is that your display was dropping frames.  What did you use to play back the video?
 

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There isn't much panning in your shot and hence not much there to cause juddering.  When I play that clip on a Premiere timeline, it seems just fine to me - and I happen to be one of those guys who dislikes judder and have been critical of the look given by 24fps that so many film makers seem so happy with.  I find it distracting.

My guess is that your display was dropping frames.  What did you use to play back the video?
 

Hi Jay,

Thanks for your comment!
I agree 24p is really different then higher framerate, but for me personnaly I like the 24p look more than higher framerates! IMHO it gives a more ''chique'' look, it depends ofcourse what you shooting. I prefer higher framerates when shooting live (for on big LCD/LED screens for ex. live bands/music) or doing ENG stuff.
Anyway, I noticed alot of judder in the movement of the person and between 20-22 secs of the clip in the left (trampoline?).

I played the video back on VLC and Quicktime (both OSX and Win7 on different computers with i7,SSD and 8GB ram or more) and in Premiere CC in OSX (tried different sequence presets and previews with C4K resolution in ProRes 422)
Even when doing a scaled export (down-scaled C4K in 1080P sequence for final 1080P export) the judder appear.

I also tried to output my HDMI from my computer in 24hz (set the display output to 24hz in OSX) to my Sony HD tv and putting the tv in ''24Hz Cinema mode'', also no difference...

I keep saying the difference is really TO big, comparing it to my Canon 650D in 1080p 24p NTSC.... That said, as a whole seeing this is my first experience with 4K. So maybe it's more normal then how i'm seeing it.

Sorry for my bad English, I'll hope you understand me well!  ^_^  :unsure: 

Greetz for The Netherlands

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Hey Mvds, nothing wrong with the clip you posted, its simply the physics of how fast you can move the camera before seeing the image strobe..

 

I think if you made a scientific test next to the 650d you would see the same..

 

(NTSC = 29.97 fps not 24 btw)

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Hey Mvds, nothing wrong with the clip you posted, its simply the physics of how fast you can move the camera before seeing the image strobe..

 

I think if you made a scientific test next to the 650d you would see the same..

 

(NTSC = 29.97 fps not 24 btw)

Animanus thanks for you comment...

There is really a difference compared to my 650D footage, that said, there are a handfull of users on the internet/forums experiencing the same... I saw it many, many times before I bring back my GH4 back!
But you make me doubt about my vision because you saying nothing is wrong with the clip.. Is a i7 machine with 8gb ram not fast/good enough for playing C4K?

Btw, I mean 60hz system settings with NTSC instead of 50hz PAL, sorry for that :)

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Hi Jay,

Thanks for your comment!
I agree 24p is really different then higher framerate, but for me personnaly I like the 24p look more than higher framerates! IMHO it gives a more ''chique'' look, it depends ofcourse what you shooting. I prefer higher framerates when shooting live (for on big LCD/LED screens for ex. live bands/music) or doing ENG stuff.
[snip]

Sorry for my bad English, I'll hope you understand me well!  ^_^  :unsure: 

Greetz for The Netherlands

 

No need to justify your preference for 24 fps.  Many agree with you.  I only bring it up because I'm particularly bothered by judder and it isn't bothering me in you clip.  I just don't see it.  I am bothered by the "shaky cam" a bit. But I'm not seeing anything like the "judder" we often see in 24 fps pans.

 

I'll play your clip on a larger monitor this weekend and see if that makes a difference in what I perceive.

What I do notice with the GH4 at 30 or 24 fps is that the rolling shutter effect is more pronounced - which I also don't like. 

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This is my first post, but longtime reader :)

 

I've downloaded the file and imported it to Premiere Pro CC.

 

Now when the file is imported in the 4K sequence or 1080p (downscaled from 4K) sequence it stutters and loses frames for smooth playback. (You can see that by enabling "Show Dropped Frame Indicator" in  the program monitor playback window top right corner. It is GREEN when there are no droppped frames and turns YELLOW when Premiere is dropping frames)

When I play it at 1/2 resolution from the 1080p sequence (downscaling from 4K) it is buttery smooth and no dropped frames.

 

What I did next is exported the 4K clip as 1080p clip at 20Mbps with maximum settings for downscaling for best results.

Resulting clip plays smoothly in MPHC, PowerDVD13, VLCplayer and in Premiere Pro once re-imported.

 

I have to say that prior to converting the clip from 4K to 1080p, it stuttered in every player I've tried.

 

The very same thing happens with my GH4 clips, and I think it's a PC hardware/software problem with latest h.264 codec unfortunately.

 

I've downloaded P. Blooms A7s 4K test recorded on Blackmagic Ultrastudio 4K and it is recorded at 345Mbps as Prores LT which plays without any dropped frames in Premiere Pro CC at full 4K resolution.

 

My PC config is:

Intel Core i7 3770 at 4.2Ghz

32GB DDR3

AMD HD7950 3GB

6x HDD all WD black 7200rpm from 1TB to 4TB

Win7 64bit

 

So pretty good configuration with full support of GPU hardware acceleration in Premiere.

 

Hope this helps a bit.

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But you make me doubt about my vision because you saying nothing is wrong with the clip.. Is a i7 machine with 8gb ram not fast/good enough for playing C4K?

 

No, it's not.  You need a video card with a good GPU (lower end cars won't cut it), and playback software that supports GPU acceleration.  You also can't use an old video card, no matter how fast It is, that doesn't support the latest version of DirectX.

 

Michael

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No, it's not.  You need a video card with a good GPU (lower end cars won't cut it), and playback software that supports GPU acceleration.  You also can't use an old video card, no matter how fast It is, that doesn't support the latest version of DirectX.

 

Michael

 

My second edit system is a six core AMD with a fairly low end GPU.  I think has something like 130 Cuda cores.  That machine plays the clip fine in Adobe Premiere 5.0.  But I've got Premiere "hacked" (not much of a hack really) to use the Cuda cores on the non-approved card and this seems to be enough to let the clip be played back OK. 

Keep in mind that when playing 4K 24p files you are dealing with a number of possibilities. 
1) If your display is less than 4K, then a very large image must be re-scaled 24 times a second and get rescaled.  Cuda cores are great for that, but if your player doesn't use them, they may as well not be there. A multi-threaded player might be fast enough to do the real time scaling - but maybe not.  Also, some kind of negotiation needs to happen so that the 24fps frames get sent properly to screen that may be running at 60hz, 72hz or greater.

 

2) If your display can show a full 4K, then it needs a LOT of bandwidth in order to push all that image data.  Remember that this data has to be pushed around uncompressed.

 

All that said, the OP did say that he re-scaled to 1080p.  So its anybody's guess what he is really seeing. But given what I see in the clip he posted, it must be some kind of fault/difference in his playback system.

One good thing about threads like this is that it gets me to test things I might not otherwise test.  The original file only plays from the camera when the camera is optioned for 24hz.  Our smaller HD TV won't deal with 24hz output from the GH4, but our larger one will.  The file looks perfectly fine when viewed up close with 24hz HDMI display on our 58" Samsung plasma TV.  Interestingly, I was just watching a documentary movie, "Searching for Sugarman" and was (once again) finding the judder in slow pans annoying.

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  • 2 years later...

I faced similar issues with GH4; jarring motion / judder when panned at 25p.

Test A: The situation seemed to get better (for good) - i meant lesser judder at 50p (of coarse the shutter speed had to be increase - Ts <= 1/00s) but the problem still remained.

Test B: The next step was to enable the variable frame rate to 75fps and consequently I also set the shutter speed to 1/320 s (~ 1/4 times the frame length) and panned it slowly enough to reduce the judder and it did reduce the judder. Well, in the final edit I increased the speed to 200% of the original footage to get something decent (subjective).

Conclusion: By the way, while test A produced a unacceptable video but contained the background audio; Test B produced an acceptable video with no audio (something that is stated to be common when VFR is ON).

I believe this video judder is either a

mechanical problem: Owing to the use of (slow) rolling shutter

OR

codec issue and I can't comprehend this.

By the way EOS 7d with similar settings i.e.(Full HD 25p) produced no judder when panned at the same angular velocity!

My work around:

USE  GH4 sparingly for tilt / pan. For a linear slide application it might still be useful as the frame traversed is not going to get amplified with distance as is with a pan, keeping the velocity invariant with respect to the distance.

USE EOS 7D with glee:)

Overall, I am still discovering the drawbacks of GH4 although I see some definitive advantages with it...Time for a serious upgrade by Panasonic / bug fix...

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