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GH2 Stutter/Judder/Strobe issues discussion
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  • @Dalefpf

    You are so strange.
    GH2 runs internal screen at 60Hz as I can understand.
    And it also do not output proper 24p via HDMI.
  • Ran a few more tests today but still no progress. I don't want to come off the wrong way but do you guys really not see the jerky motion and constant strobe when you pan? Regardless of of monitor settings and such. I can see it plain as day on the lcd as I'm filming. I know the proper speeds to pan and I know what 24p looks like. I'll be shooting on a Canon in about 2 hours from now and I'm looking forward to it at this point. The GH2 kills Canon in every way except for this which is so frustrating. I keep boxing this thing up and then pulling it back out to test it again because I'm just so dumbfounded by this. The fact that many people don't complain about this leads me to think I'm crazy. But, I know cameras and do this for a living full time. Fu*k me, I guess. Just can't stand being bested by this damn camera. Okay, I'm done. Rant over...... Thanks again for all replies and helpful comments. Best of luck to you all.
  • If I can find the time, I plan to use After Effects to scan the motion of a dolly move and see if all of the frames are moving the same amount. It seems to me that there is some unevenness. I'm also curious whether shooting at 1/60th of a second vs 1/50th. I know that's breaking the rules, but I'm curious if it might work around the overly smeared motion. Has anyone else looked into this?
  • @Dalefpf

    I agree with you the studder is more pronounced in the GH2 24p footage. Hacked and Unhacked. Shot some steadicam footage with gop3 and about 47mbs the other day. Didn't notice the judder/jitter till viewed on 46" screen. Didn't show up on my 28" calibrated computer screen. Looked at some old GH2 unhacked footage, it was there. Checked some 5D Mkii footage. It wasn't there. When I get a moment, I am going to go shoot some similar steadicam footage on the 5D Mark II to compare. I'm guessing it is going to be there. I may also fire up a projector to see if it shows up there but guessing the same results will show as with the 46" TV. I do not see the judder at 60p nor do I always see it at 24P. I'm guessing it is more pronounced/noticeable during different types of shots/conditions.
  • There are several separate factors mixed in together in this GH2 judder issue. To those who say "that's just what 24P looks like"
    For that guy, clearly something wacky is going on. But I personally don't think it is anything to do with the camera - it's somewhere in the decode/edit/playback workflow. However for others of us, that clip played completely normally with none of the double image seen in those screengrabs.
  • For me the issue is not 24p, but whether the 24p on the GH2 looks juddery compared to other cameras like the GH1. To me, the GH2 is very slightly less smooth. I'm sure that some people will see 24p slightly differently than others. For example, some people see rainbows in projection TVs, others do not.
  • As strange as it sounds, I've noticed a dramatic difference between televisions that have a 240hz refresh rate over those which display at 120. It seems almost "too smooth" or different, at least for a monitor. I'm not completely sold on it but then again I've never had one for myself. Maybe it's force-of-habit from watching last gen televisions.

    Anyways, I think you'll always see judder in certain scenes when filming at 24fps. Your eyes will always catch it if you're looking for it in the first place. When filming at 30fps or higher it's less noticeable if not apparent altogether.

  • I am wondering if some if this concern actually revolves around the different ways that people convert their original files, and how hard it is for some computers to accurately handle a smooth playback of certain MTS footage. Just an idea.
  • Some optical stabilization (antishake) systems could result in stobe-like output during panning.
  • There have been studies that show that the 24fps rate, because it is visible, actually contributes to the psychology of suspension of disbelief. Narrative videos "feel" different at 30fps than at 24fps.

    Chris
  • I notice the judder effect in high budget movies (at the theatre) as well, sometimes more so then others depending on the action in the scene or the size of the projection itself. I'm guessing that whether you have a digital projector or reel-to-reel it will always playback at 24 frames per second when at the movies. From my limited experience our eyes cannot differentiate anything above 60fps and even 30fps still looks fairly smooth in my opinion, but 24fps is a motion picture standard. I guess the majority of people don't notice the difference between all these refresh rates and/or don't care.

    To me as long as it doesn't suspend your disbelief or deter your interest, the frame rate game isn't so important if you're not concerned with slow-motion playback.
  • I think the grass looked good because it was covering less space from frame to frame and could be covered by motion vectors. The water moved farther from frame to frame and probably couldn't be covered by motion vectors. At that point the codec probably decided to use intra-frame encoded macroblocks but didn't have the remaining bandwidth to cover them, so the macroblocks were "skipped". I've noticed that with the hack, there are much fewer "skipped" macroblocks than with the factory codec settings.

    Chris
  • I think there are two issues that affect this: 1) The 60hz refresh rate on most monitors. 24fps will never look right because it has to be telecined - the result is an uneven looking cadence. 2) When the GH2 codec runs out of bandwidth it just abandons encoding macroblocks - the result is that some movement will look like it is changing at a slower rate, like once every 1/2 second. This usually shows up only in parts of frames; you could have grass waving and water moving - the grass waving will look fine but the water flow stutters at 1/2 second increments. Somebody posted a video showing this. The hack helps a lot with this sort of thing.

    Chris
  • @Dalefpf
    There are certain charts published by ASC regarding the judder avoidance. These charts rely pretty much on a "7 seconds rule"
    In a pinch for a 24fps footage shot at 180º shutter (1/50th of a second for GH2, I guess) the panning rate should be such that an object within a frame would move from one edge of the frame to another (left to right or right to left) in 7 seconds.
    One would assume that if you shoot at higher shutter speeds the timing changes accordingly, ie 14 seconds for a pan from edge to edge when shooting at 1/100th of a second.
  • @Dalefpf

    I don't get that is wrong with 24p mode in GH2.
    All that can be different is sensor scan method and speed. It causes jello and other weird things.
    If you are used to CCD or film it is very easy to notice.
    Fast small CMOS cameras can also have fewer jello.
  • @Dalefpf

    I hear what you're saying. I thought the motion of the GH2's 24p mode was poor from the start, and that comment in the manual about "after-images" was just weird. My first impression was that the LCD and the footage both looked sort-of like old silent film.

    Before you give up on the camera completely, can you try one more test? Shoot something using the 80% speed mode, which will give you a true 30 fps recording. Conform it up to 30 fps in your editing software and let us know if you still see the weird judder.

    Also, a reminder that if the shutter speed is longer than 1/25 the frame rate actually drops to accommodate it. You can sometimes inadvertently be shooting at a framerate lower than 24 fps this way.
  • Loaded a few more stable hacks and ended up with the same results. Went back and changed my monitors to 48hz just to make sure. Looks the same. You can see it in the actual lcd on the camera anyway. I read on another post that the motion looks like old Charlie Chaplin films. I think that's a good observation. Though not really what's going on. Anyway, I haven't gotten any real response as to how the hack might alleviate this so I guess there is no real answer right now. I'm sure there will be more info in time. This topic always turns in to the same old " Hey buddy! That's what 24p looks like" type thing so I don't want to press it. So best of luck to you all and thanks for the responses. This is such a neat project so I hope it yields fantastic results down the road. I'll gladly pick up another Gh2 in the future if things in this arena change for the better. For now, this camera is just not ready for prime time. Though I know you can make a good film with any camera. Blah, Blah, Blah. ( Want to avoid the same tired arguments. )
    Cheers!
  • Matt, thanks for the input. I actually do that on some monitors. Don't take this the wrong way but I work work with footage, from different cameras, everyday. Been doing it for years. I know what 24p looks like. I'm not here to debate that in any way. I, and a few others, believe there is something a bit off with this particular camera. That's all. No big deal. It's a consumer product. What do you expect?

    I've been editing a civil war documentary on and off for a company over the last year or so. They started out with Canon xha1 cameras, I believe. The project was already picked up and just needed to be finished. Three quarters of the way through they had purchased a few GH2s and started using them as well. Now, battle scenes have a lot of movement. 24p looks pretty bad in that scenario anyway but the GH2 footage was dreadful. Actually to the point of one of the executives saying that he thought he was going to have a seizure. This was on a state of the art projection system, by the way. You could clearly see the difference. They came back to edit the footage and we decided to take all the GH2 stuff out. Next showing went off without a single comment and everyone was pleased. Except for the filmmakers who lost a lot of good scenes. Now, I know I didn't put one piece of technical information in this story but that's the way it went down. There was no comparison between the two when you saw it projected.

    I have no faith in the GH2 as is. I do have faith in the incredibly smart people working to hack it. From what I have seen, I do believe you could shoot and sell a movie with this camera. You would have to keep motion to a minimum compared to most others. Like I said earlier, most of the footage people are drooling over are static shots. They look great. Just not going to cut it in real business of selling your movie if it has a lot of movement, that is.

    Realistically, I doesn't bug me that much. I'm just another cheapskate looking for an inexpensive movie camera. But, I love the idea of the hack. If there is no way to overcome the look of the motion then I'll just pitch it and move on. Already did that with my first GH2. Just picked up another to see how the hack might affect it. So, sorry to disagree and I appreciate your help.
  • Trust me, it's normal for 24p. THERE IS NOTHING ABNORMAL ABOUT THE GH2'S 24P MOTION RENDITION!

    If you want smoother motion, then 24p is NOT for you. Shoot in 30p instead, and at least that will be in sync with most monitors.

    If you want to see 24p in its best light (this applies to any camera, not just the GH2) then set your monitor to either 48 or 72hz by making a custom refresh rate (unless it exposes it as useable already). Your 24p will never have looked SO smooth.
  • Okay, I checked out the 3 GOP setting this morning and it's not really helping. Also, I did read that entire thread a while back and looked into the playback issues. I don't believe that is the problem. And, trust me, I wanted to believe that was the problem.The thought of an $800 camera is just too tempting not to try anything to make it work. So, does anyone here believe the GOP stuff could help with this? Or, should we look at something else? Any feedback would be appreciated. I'm going to try a few more stable settings throughout the day. I'll report back if I see any results.
  • Or just play it. Most people editing video will have power to spare for playback.
  • @Angry_C

    That's an informative thread and really leads me to believe (aside from the sharpness issue) that a lot of this is the playback device. I had to add the CoreCodec to my Win 7 64Bit laptop and set Windows Media Player to use it before any of my clips would play correctly. Before I did this I would see a judder, stutter, etc. especially in a pan because of the heavy motion. When I stick my SD card in my Sony Blu Ray player, it finds my original files and they play without any of the stutter to my HD monitor. I think the only real way to prove if the strobe/stutter is there or not is to ingest it into the NLE using a high quality INTRAFRAME codec that is known to play without stressing your CPU - e.g. DNXHD175 on the Avid - and see how it plays back then with AVCHD out of the mix.
  • I have always wondered whether this was deliberate. I the GH2 manual, for 24p, it states for the definition for 24p:
    "Record motion pictures with afterimages like a cinema." (P105)
    Afterimages?
  • I see some strange uneven stutter on my 24P footage as well. It's as if not all of the frames have the same amount of motion on them. As I've been reading more here about GOP, it seems possible that the 15GOP structure may play a role. I've switched to 3GOP but so far I have not shot any smooth dolly shots that really show this uneven stutter.

    By the way, I've worked with film several times and this phenomenon is very different than the 24 fps film judder I know and love.
  • So, I loaded one of the GOP 3 settings and I would have to say it tended to help a bit. I'll look at it again outside in the daylight. Maybe there is something to this. I hope someone who knows more than I can ring in on this subject. It's frustrating because there really is only a handful of people complaining about this issue. I sometimes think I'm crazy but when I compare the footage with any of my other cameras I just don't see this much judder. Hell, I edit footage everyday and when I got some GH2 footage in I recognized it right off the bat.