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GH2 in 24p: noticeable "strobe effect" with any motion in frame?
  • 259 Replies sorted by
  • It actually drops into frame doubling mode, 2 frames the same when you step thru them in an editor or player. Sames as the GF cameras, but media-info still reports 50 or 59.94fps. So yeah effectively it is 25 or 29.97fps.

    UPDATE, just tried my GH2, it also drops to frame doubling mode when shutter is less than frame rate, but it does hold bitrate better than GH1.

    I encountered this when i first used the GH1 2 years ago, i accidentally knocked the thumb wheel in shutter priority mode, bitrate and video IQ was horrible, totally ruined footage.

  • drops into frame doubling mode, 2 frames the same

    Two identical frames @ 50fps =25 fps, (shot on twos). I wonder what this does to shutter-blur?. A single, half-blur, seen twice with a stuttering gap in the middle where un-filmed movement takes place? (!) Best avoided, I think.

  • Many thanks to Astro! And of course to mo7ies, who started this conversation! I've been testing different versions of hacks about 6 months now and haven't been satisfied, how motion is captured in GH2. I'm too in PAL area, but in theatre versions 24p is good way to go. I started testing GH2 hacks, because I thought I could use it in my next feature length documentary film. Image quality in it itself is great, but cinematic motion is another very important issue we need to have to get a real filmic feel for the material. I hope that this conversation is pointing out this important issue to get better quality from already great hacks!

  • @driftwood @LPowell @Ralph_B

    Actually this is a very good question, @MisterJ

    Do the esteemed hack developers take into consideration GH2's excessive motion stuttering in 24H mode, and can they do anything at all, technically, to improve (minimize) this unpleasant motion stuttering/strobing at 180deg shutter?

  • To be fair, there's only a select bunch of people that have found this a problem.

  • @itimjim To be fair, only a select bunch of people need GH2 hacks to begin with. What's your point?

    Clearly, here we are talking about people who do care about image / motion quality. Excessive motion strobing on GH2 is very real, and this thread shows that actually MANY people noticed and tried various workarounds to circumvent it. (and some people even gave up using GH2 as video camera altogether because of motion issues!)

    Current workaround is to use 1/30 or 1/25 shutter in 24H mode. This introduces more blur than the standard 180-degree shutter (1/50) would, and thus masks/smoothens the strobing.

    Question is... do hack developers have any technical ability to fix the strobing at 1/50, and if yes, are they trying?

  • This is spot on mo7ies. I think that next big step making hacks even better, could come out concentrating how fluid is cinematic motion in GH2-videos. I'm not complaining. It's amazing what I can get from a price of GH2 and great hack. But still, I just think that developing better hacks makes better looking film/video/Tv -projects. I'm not a pixel peeper and I think that picture vice there already is many great hacks. But as filmmaker I think at the moment, that if I use GH2 in my film, I must compromise too much if I want to have a cinematic feel and movement in shots. Meaning how fast I can pan or tilt? What kind of objects I can have in a front of a frame during a dolly track? Even how people are moving in a frame, that I wont get any strobing in shot?

    Most of the shots I see posted here are static ones. And there is nothing wrong in that, but once a while you need to move your camera. I would like to do it without worrying if can I use that shot in edit.

    All the Best.

  • Correct me if I'm wrong, but isn't this percieved stutter effect caused by clipped highlights? When highlights are clipped they will create a hard edge on overexposed areas, even when there's motion blur in the image.

    I would suggest a motion test where the scene is shot underexposed and then boosted in post, where highlights can be handled better.

  • @mo7ies My point is, is that many actually "don't" see, or notice it that much it becomes a problem. Not that much that they have to compromise with low shutter speeds. If it was that much of a widespread problem we'd all be up in arms about it.

    There's a chap on here who can tell the difference between a 1/40 and 1/50 shutter. My eyes certainly can't, and neither can the vast amount of regular viewers. My visual acuity just isn't up to the standard of some of you. I've read through the whole thread, and I still can't fully understand what you are going on about and when the conditions are repeatable.

    I'm quite critical, I can usually recognise when something has been pulled up or pulled down, shot with a faster or slower shutter (although not by differences of 1/10). But I just can't see it in this case. I'm not saying you're making it up, far from it, I just don't think it's that big of a problem, especially in contrast to the price ratio of this camera.

  • @mo7ies All AVCHD hacks have inherent limitations - they cannot alter the properties of the camera's image sensor, nor the electronic shutter that controls it. Likewise, no one can alter the properties of human vision to make 24fps video look less stuttery than higher frame rates. As @P4INKiller pointed out, high-contrast highlights can emphasize this inherent stutter, as can fast shutter speeds.

    @MisterJ "Fluid cinematic motion" is precisely what I aimed to produce with Flow Motion v2:

    http://www.personal-view.com./talks/discussion/3337/gh2-flow-motion-v2.02-spans-in-hbr-25p-24h-720p/p1

  • @LPowell wrote:

    no one can alter the properties of human vision to make 24fps video look less stuttery than higher frame rates.

    But that's not what we are trying to achieve here.

    What we are saying is that GH2's 24p is visually more strobing than, say, Sony F3's 24p under exact same conditions.

    It is very prominent, and annoying to the viewer.

  • @mo7ies Sorry, I don't know of any way to make a GH2 look as good as an F3!

  • I can see strobing with both the F3 and the Red Epic at 24p with 1/48th shutter too. It all depends on camera and object movement, contrast and DOF. To me it's always a bit more than with analog film.

  • @Misterj says

    Most of the shots I see posted here are static ones.

    Yes, because one of the reasons 24p stutters is under motion-blurring. I have repeatedly asked for users to post stills from stuttering video to see if it's blurred as much as it should be, given the supposed shutter setting.

    SO far, i've only seen 2 examples on this thread - both suffering from momentary handheld shake. That's not good enough. I'm quite sure there are other 24p stutter culprits. But we have to rule out the obvious one first. As I keep saying (sigh):

    I've never seen stuttering video which didn't suffer from under-blurring.

    @LPowell wrote:

    no one can alter the properties of human vision to make 24fps video look less stuttery than higher frame rates.

    Well, no - but since we can correct it using motion-blur in post, we can adapt to suit the human eye. @Mo7ies uses 1/30 shutter to do it in-camera.

  • @itimjim

    To be fair, there's only a select bunch of people that have found this a problem.

    That's true - but these threads are linear and when we repeatedly raise the perception aspect it ends up sending us around in circles. I really would like to do a synopsis of this entire phenomenon, including the valid aspects of viewer perception and the context in which we view the footage.

  • @nomad With the F3 can't you turn the shutter off to sort out strobing like the EX3? It works like an auto shutter.

  • Ok seriously this is crazy... The strobebing on the GH2 is what gives it such an authentic real 24p look. Have any of you guys complaining ever shot Red or Alexa and watched the uncompressed non-vimeo footage? This is how they look at 24p. It's the real-deal digital cinema look. All frames rendered individually (Intra patches) means more stuttering. This is a good thing. The motion on something like the F3 screams digital to me for this reason alone... the temporal compression smooths out the stuttering to a degree and ruins the true-cinema motion. If you like "smooth" realistic footage... use 60i or 720p60fps mode. If you want cinematic motion... you really can't get any better than the Intra-GH2 for under 20k...

    @itimjim

    There's a chap on here who can tell the difference between a 1/40 and 1/50 shutter.

    This is actually pretty noticeable. And using something like a 1/30 shutter is getting into cruddy lookin' footage territory...

    @mo7ies

    What we are saying is that GH2's 24p is visually more strobing than, say, Sony F3's 24p under exact same conditions.

    Well yea, and this is why the F3 (internal codec) has a bit more of a video look to it... even with the extra latitude. Temporal compression.

  • Would it be better if I compared GH2 (unfavorably) to Canon 7D's 24p?..

    I start thinking that maybe this is a psychovisual (invented word?) phenomenon.

    Clearly, some people see it (and bothered by it), and some people just don't. Kind of like rainbow effect on the old-time DLP projectors...

    I thought we established this earlier in the thread, but if not, here goes: GH2's 24p motion is MORE stuttering than what is usual for the 24fps time sampling. To me, it looks like a night-club scene with strobe light on - for the lack of better analogy.

    I recently had a chance to use my GoPro HERO2 camera, and it has very similar unpleasant motion stutter - in 1080p30 mode!

    If I had to guess, I'd say we are dealing with not enough bandwidth to record enough data when some motion is in frame. Once again, just a speculation. Whatever it is, the effect is pronounced. I see that people pounce on F3, which probably was a bad example. So then, let's compare to Canon 7D - which had way more pleasant 24p motion rendering. Is it too much to ask for GH2 to have the same 24p motion quality as Canon 7D? Now that both devices are clearly of the same class?

  • Well, for the 7D, as much as a fan of it as I was... and I still use it, has a muddiness to the motion that is again, caused by long-GOP temporal compression. This is why I really don't like to use my 7D any more for personal projects.

    But... there's no reason to NOT like this, it could just be your personal taste, but the motion from Intra-GH2 patches is nearly identical to that produced by an Alexa, Epic, Scarlet, probably F65 (haven't worked with footage yet though), and yes, even a real film DI. This is just how real 24fps footage looks.

    I think it's just personal preference here. You must just prefer the smoothed out long-GOP look. It's kind of like how some people prefer the heavy compression of lower bit-rates because it takes away the images texture and looks "less noisy" to them.

    But I can assure you... besides some weird possible glitch...the GH2 isn't stuttering more than other 24fps cameras, it's studdering completely accurately. Other cameras like the 7D, F3, AF-100, are studdering less.

    If I had to guess, I'd say we are dealing with not enough bandwidth to record enough data when some motion is in frame.

    Kind of backwards here. Not having enough bandwidth to render all the motion is what causes the GOP to "blend" frames, for lack of another word, and LOSE some of the studdering that the footage should have. This is actually what you seem to prefer.

    Plus, where's the logic in a GH2 intra patch with 100mb/s+ not having enough bandwidth for motion... but the 7D you referred to, reproducing motion more faithfully ,with only 50mb/s? Or the F3 with only 28mb/s?

  • @mo7ies said

    not enough bandwidth to record enough data when some motion is in frame

    That's one idea which deserves its place in any synopsis as well as any other.

  • mo7ies, the GOPro is a variable shutter speed camera that adjusts exposure using mostly shutter speed, usually at a very high rate 1/500+ in average outdoor conditions for what it was designed for. Of course it will display unpleasant ( for some) stutter motion, it's designed this way because it is an action cam that is subject to high camera motion. If it were 1/60 the results would be mostly blurred video and very unhappy users. Why even mention this camera in this thread?

  • @mo78es - "I'd say we are dealing with not enough bandwidth to record enough data when some motion is in frame."

    Any downloadable footage that demonstrates this speculation?

  • @Roberto

    not enough bandwidth to record enough data when some motion is in frame

    That's one idea which deserves its place in any synopsis as well as any other.

    Not really. Like I said above...

    Where's the logic in a GH2 intra patch with 100mb/s+ not having enough bandwidth for motion... but the 7D you referred to, reproducing motion more faithfully ,with only 50mb/s? Or the F3 with only 28mb/s?

    But as filmmaker I think at the moment, that if I use GH2 in my film, I must compromise too much if I want to have a cinematic feel and movement in shots. Meaning how fast I can pan or tilt? What kind of objects I can have in a front of a frame during a dolly track?

    Haha, oh sweet irony. This is EXACTLY what directors and cinematographers run into when shooting film and digital-cinema. Most good directors, DP's, and operators that shoot the high-end films, have to be constantly aware of the pan/dolly speeds they can use and plan around them. This is just what you have to deal with when shooting 24fps! Use 60p for sh*ts sake!!!

  • Another thing to consider, when comparing and talking about the temporal look of 24 frame footage, in film you basically have a black frame between each image. As far as I know, no digital camera yet reproduces this. Instead you have image, image, image..

  • @Rambo GoPro reference was to illustrate that GH2's motion looks similar to the much lower-class video acquisition device which is HERO2 camera. I do understand your point that Hero has very high "saving private ryan" shutter speed outdoors in bright light, which I'm sure you're correct about. Then why would GH2's motion look very similar at only 1/50 shutter, which is 10x slower than 1/500 shutter of Hero cam?