GH2 24p Cadence "judder"...
 

Hey everyone,

I am sure that it's not just me who sees the "cadence judder" on the GH2 while in 24p mode. I have tried different hacks, and it doesn't fix the problem.

I have uploaded a video which illustrates the problem pretty well. Look at the football if you don't see what I mean. Settings were 1080p24, 1/50th SS.

https://vimeo.com/37309808

Any ideas on how to combat this? Do the Canon's (5D II, 7D, T3i, etc...) have this issue?? This is an unacceptable problem. Any ideas?

Thanks,

Steven

PS: That's as smooth a pan as I have ever done, and it still looks choppy!

Re: GH2 24p Cadence "judder"...
 

Do you have image stabilization switched on on the lens or in the menu?

Re: GH2 24p Cadence "judder"...
 

It is on on the lens (14-140 if that matters), and when I looked to turn it off in the menu, it has three options, but none of them say that it's disabled...

Re: GH2 24p Cadence "judder"...
 

I'm no expert.

What I've read, however, and and based on my limited experience:

The pan you demonstrate is at least double the speed you can go and expect a smooth pan in 24p mode.

Panning in 24pm is best done very slowly. I personally try only to pan when following a subject in 24p, when possible. When following a subject the background jitter or whatever is not noticed because the viewers eye is on the subject of the shot, not the background. You will see this in films that cost $100 million to produce. If it's shot with film, they will often have the same issues, but they shoot knowing these things.

24p requires a different shooting style than 60i or 60p, and will produce problems no matter what camera you use if you pan too quickly.

Re: GH2 24p Cadence "judder"...
 

I think Jeff is exactly right.
The lens test I just posted was in Cinema mode and has the same thing.
The compression in Vimeo seems to exaggerate it.

Re: GH2 24p Cadence "judder"...
 

Now that you mention that Don, I forgot that. Yes, Vimeo can be very bad that way. I've had pans that were silky smooth and shot in 60p, but they appeared jittery on Vimeo. I found I was better off giving Vimeo 60p and letting it's encoding convert it to 30p, rather than giving it 30p, seems to work better for some very strange reason.

Re: GH2 24p Cadence "judder"...
 

The 'Off' option on the menu is only there if there isn't an actual physical on/off switch on the lens itself, so if you're using the 14-140mm it won't be there.

Try turning off the OIS and see if that helps. The OIS on the GH2 is really for stills, or else for handheld static shots. For anything else, on this and any camera, it can produce a nasty stuttering as you move. I haven't experimented with OIS "Mode 3" which is specifically for panning - better to turn it off if your pans are smooth in the first place.

Re: GH2 24p Cadence "judder"...
 

Samuelson's Manual For Cinematographers suggests as a guideline that the maximum panning speed at 24fps should be the speed at which it takes a static object 4 seconds to pass from one side of the screen to the other (p.314). Your pan is a little faster than that, but not by much.

Manual for cinematographers - David W. Samuelson - Google Books

This is one of the things that makes film look like film, and one of the advantages of interlaced footage (at 50i you can pan twice as fast, for example, which is very useful for sport etc.).

Re: GH2 24p Cadence "judder"...
 

Slow your pans down to 6-7 seconds to go from edge to edge and you will see an improvement.

Re: GH2 24p Cadence "judder"...
 

It's all about perception as well. When we watch movies we don't really think about it because we are wrapped into the story. When you shoot your own footage and edit you are more focused on analyzing the look and motion and it will stand out more that something is a little off. When everything is all put together and tells a story you will not notice it as much.

Re: GH2 24p Cadence "judder"...
 

I'll try experimenting with Mode 3 and let you all know how it looks.

SB

Re: GH2 24p Cadence "judder"...
 

Would a higher bitrate hack help combat this?

Re: GH2 24p Cadence "judder"...
 

No, only a higher fps would help, but then it wouldn't be 24fps any longer, it would be 60i, or 60p, or whatever frame rate you chose.

Here's a quote from the Wikepedia entry re: 24fps

"In general, 24 frames-per-second video has more trouble with fast motion than other, higher frame rates, sometimes showing a "strobe" or "choppy" motion, just like 24 frame/s film will if shot as if it's video, without careful panning, zooming, and slower camera motion. It is therefore not well-suited for programming requiring spontaneous action or "reality" camerawork.

It should also be noted that while the strobe of 24p is in many ways considered a disadvantage, it's also part of the "film look." 24 frame/s film strobes in exactly the same way." 24p - Wikipedia, the free encyclopedia

To be clear, I must qualify I have very limited experience with 24p, I've shot maybe four events in 24p, but my experience pretty much validates everything I've read on the subject, which is pretty well summed up in the above quote from the Wikipedia quote above. Motion is not handled well at all. Additionally, it seems images are softer, and obtaining manual focus using on-camera LCD seems much more difficult, but that may be a mis-perception on my part. Overall I dislike shooting with it, it's more trouble than it seems worth, but I really do like progressive as it uploads to the web so much better than interlaced without conversion to progressive.

Re: GH2 24p Cadence "judder"...
 

I agree with you, Jeff. It's just not something I'm use to, coming from 60i -> 30p, and then going to 24p and seeing it strobing and such. But it sounds like it's just something that we're going to have to live with, eh?

Actually, I was perusing around the internet and found an interesting article on the motion characteristics of film, and how to make the digital signal look like film.

Granted, it IS $14k, and it's a filter you drop into your matte box. And you need a genlockable camera.

Anyway.

SB

Re: GH2 24p Cadence "judder"...
 

Steven, I have examined threads over the last couple of years regarding 24fps, but it was the Wikipedia article that clarified things for me so much last year when I was researching the subject.

I dissed 24p in the past before ever trying it, and it so happens, that after I shot my first wedding in 24p that what I read was correct. 24fps is not ideal, by any stretch, for run and gun shooting, which is primarily what I do as a wedding shooter.

Conversely, a visit to the website for Pacific Films or any of the many other skilled shooters using 24p and it becomes clear that 24fps can and will work for run and gun, if done with the correct camera techniques. I suspect it can take a good while to master the methods needed to produce above average looking video using 24p.

I hate it, it's too soft for my taste, and too difficult for me to get a good focus, it's really distracting for me. On the other hand I've shot some decent video when I got lucky here and there using it, but I have an awful lot to learn before I can say I'm halfway proficient with it.

Re: GH2 24p Cadence "judder"...
 

A couple of 24p judder tips:

There is a certain speed of camera movement that causes noticeable judder. It has to do with the visual information moving past the sensor in relation to the frame rate. A slightly slower pan will fix this but also a quicker pan can also reduce judder. You can get judder in 30p but as the frame rate increases the exact pan speed where judder is caused is reduced. And when it happens, it's less pronounced. At 60 frames per second (progressive or interlaced), judder is essentially eliminated.

Seeing judder also has to do with the perceptions of the viewer. The same pan rate on a landscape that produces disturbing judder will not have the same perceived problem if there is a person walking at the same pan rate in the center of the shot. The attention is on the person not the landscape especially if the person is close to the camera.

Compression sometimes reduces motion blur which increases the appearance of judder.

Re: GH2 24p Cadence "judder"...
 

Right William, when following a subject, the background blur is not important.

I watch feature films shot on film and they all look the same, when following a subject the background looks like crap, but I only notice it because I'm looking for it. When I'm immersed in the film, though, I don't notice it. On the other hand, wide establishing shots, particularly outdoor shots, shot in film, will look relatively "bad" when they pan, there is no way around it, apparently. That is why they so rarely pan for those shots, I'm sure.

Question William: it would seem obvious, but I'm not sure. When doing a "moving" shot in 24p, where the camera is moved by hand or steadicam to get a shot, say of a bride's dress or of anything else, the judder problem will be no different, or will it? Is there a technique for doing moving shots that minimizes the problem?

Re: GH2 24p Cadence "judder"...
 

There might be a tracking speed that is not good for certain shots but as I understand it (and experienced it) judder is more obvious on steady pans or tilts than erratic hand held shots.

I forgot to mention that shutter speed is an important factor as well. Since cameras like the GH2 do not have a true film shutter speed but decimal increments, judder will happen in very slightly different circumstances. And a high shutter speed, which we might be tempted to use as a way to force DOF, can cause really disturbing judder in pans and action shots. Once again, following a subject reduces the perceived judder.

Re: GH2 24p Cadence "judder"...
 

Thanks William, it's interesting that moving shots are not as affected. I do few moving shots and very little handheld, but's it's nice to know that it is not so bad as a pan. Good stuff, thanks. I thought I had seen some very elegant moving shots in 24pm but can't remember specifically.

Re: GH2 24p Cadence "judder"...
 

Also I don't think this was posted but having the shutter speed at 1/30 helped my footage out a ton as movement blurs instead of juddering along like you have shown...

Re: GH2 24p Cadence "judder"...
 

David, can you post some 1/30 tests?? Is it obvious that the SS is a lot slower?

I think some of the problem might be shutter speed. Maybe a hack with 1/48 would do the trick?? Because currently we have only 1/50, which equates to ~172 degrees, whereas 1/48 would be the real 180 degrees...

SB

Re: GH2 24p Cadence "judder"...
 

I'm sorry guys but the video posted on vimeo looks bad. And that IMHO has nothing to do with progressive shooting. Pogresive definetly doesn't look like that. The judder in that video isn't consisten by far. Progresive judder should be consistent not on and of like this. And progressive judder looks a lot different then this. I just might go this far as to say that this is not progressive judder but it looks like droped frames. The video in the video stops for a moment a couple of times. That to me

Seriusly, am I the only one seeing this?

Have a look a this Alisters video: Progressive v Interlace and using the shutter to reduce motion blur - YouTube
@Steven: do us a favour and do another pan, and this time do it evenly. Put a rubber band on the handle of your tripod and pul on it. This will produce the most even motion without unwanted jerks. Like this: Best Camera Trick Ever! - YouTube
Then upload that again and give us the link. Also it would be best to look at the video in a NLE. Before vimeo compression.

Re: GH2 24p Cadence "judder"...
 

No, I see it also but I'm not sure what to make of it.

William, if you do another test shot you can upload the native file to Vimeo. They will still compress it but the original file is not compressed and can be downloaded. We can view it that way.

Re: GH2 24p Cadence "judder"...
 

I have tried 10 to 20 flavors of the hack so far, and some seem more likely to have this dropped frame look than others. I would recommend trying some of the hacks that have been released in the last two weeks. Also, the behavior of the camera may be affected by the lens you are using. Panasonic lenses with OIS are demanding more of the GH2's processor time for OIS and lens correction calculations, and the hacks push the processor to the limit. Some of the hacks, for reasons I don't understand, are choppy for the first few seconds of filming before they reach full data rates. You can see this if you analyse the files in Streamparser. Finally, the Panasonic OIS itself can often exhibit jerkiness. If you shoot with a non Panasonic lens and select the "shoot without lens" option in the menu, the GH2 will have a little bit more cpu available for the hack.

The various hacks and patches really boost the capabilities of the GH2 but none of them are without their limitations. To get the best one(s) for your purposes can require a lot of trial and error and may still mean that you have to adjust your shooting style to minimize problems. I have been able to get very smooth 24p pans. The hack I have used the most is the old Aquarius 2. I would recommend a specific newer one, but I have been trying so many I would have a hard time remembering which one is best for this. I'm still waiting for a really good HBR patch for 30p that will work on my Sandisk Extreme 30mbps cards and can handle busy natural scenery well.

Pat

Re: GH2 24p Cadence "judder"...
 

@Sanjin. Steven said the pan was smooth. It looked worse to me than 24p judder, which is why I mentioned the image stabilization early on, but the extra nastiness could be down to compression/streaming. Did you try turning off the image stabilization, Steven?

The difference between 1/50 and 1/48 is very slight and most UK features (X-Men: First Class, Kick Ass etc) are shot at 1/50 (with 172 degree shutter) to cope with the 50Hz mains frequency. If movement in features (and progressively-acquired PAL TV/video for that matter) were as bad as all that, then I don't think 24fps would remain the world's dominant, standard frame rate.

Re: GH2 24p Cadence "judder"...
 

Steven said the pan was smooth. It looked worse to me than 24p judder, which is why I mentioned the image stabilization early on, but the extra nastiness could be down to compression/streaming. Did you try turning off the image stabilization, Steven?

The difference between 1/50 and 1/48 is very slight and most UK features (X-Men: First Class, Kick Ass etc) are shot at 1/50 (with 172 degree shutter) to cope with the 50Hz mains frequency. If movement in features (and progressively-acquired PAL TV/video for that matter) were as bad as all that, then I don't think 24fps would remain the world's dominant, standard frame rate.

Re: GH2 24p Cadence "judder"...
 

Rolling shutter magnifies judder.

Re: GH2 24p Cadence "judder"...
 

@Andrew: yes. I didn't saw your post. I'm totally beat today so I just scrolled over the thread and gave a very quick reply. As you can see from the writing:)

Anyway, this in not progressive judder. It's something else that can be almost 100% fixed. As all of you stated before; this hacks are a hassle. Does that judder happen when using the original firmware? I think that installing the original firmware and repeating the test should be your first logical step in figuring this out.

Re: GH2 24p Cadence "judder"...
 

Here is my 24p panning at 1/30 shutter speed...

https://vimeo.com/38248835

Re: GH2 24p Cadence "judder"...
 

David, is that a hack or stock?

Re: GH2 24p Cadence "judder"...
 

The Vimeo file is 30p. The judder is either because you edited 24p on a 30p timeline or because Vimeo converted it to 30p after uploading. This is an example of how 24p looks when played back at 30p using duplicate frames.

Re: GH2 24p Cadence "judder"...
 

@Eric: I made sure that I was editing the video at 23.976 fps. Could this actually be my problem?? Should I be editing at an even 24p rather than 23.976?

Also, is vimeo converting my 24p stuff to 30p?!?

And I am not sure I like the look of the 1/30 SS stuff...

SB

Re: GH2 24p Cadence "judder"...
 

Hacked but the only thing I did was boost the bit rate from 22000000 to 42000000

Re: GH2 24p Cadence "judder"...
 

It's doubtful that any hack would help much with judder. Generally the hacks are dealing with bit rate increases that don't change the limitations of capturing movement with a limited number of frames per second.

1/30 shutter speed certainly would reduce judder as the image smear connects the frames better. It certainly makes the pan shots posted earlier smoother. However we start to enter a realm of issues caused by slow shutter speeds which start to translate to slower frame rates. Essentially frame rates slower than 18 frames impart a dreamlike quality to movement. 1/30 shutter speed works with modest subject motion but fast motion starts to look odd.

Re: GH2 24p Cadence "judder"...
 

Using 23.976 fps is correct, but there is something wrong with your workflow. The streaming video file on Vimeo is 30p and has the exact 4:5 cadence that you get by duplicating one frame out of every 4 to fit 24p into 30p. Here is the output from mediainfo for your Vimeo file:

I would recommend checking the original file you uploaded with mediainfo.

http://mediainfo.sourceforge.net/en

Re: GH2 24p Cadence "judder"...
 

Definitely something wrong with his workflow.

Re: GH2 24p Cadence "judder"...
 

Workflow aside. Just thought I would chime in and give you guys a link that shows some really good motion characteristics using 1/40 and a Orion hack for the gh2 that is optimized for the motion.

https://vimeo.com/35999739

The guy is really helpful and is a font of information. I think the motion looks as smooth as most of the high end cameras Ive seen.

Maybe the hack can help some?

Re: GH2 24p Cadence "judder"...
 

Steve, I'll have to look into that hack and those settings some...

But since the last few posts have talked about workflow, I thought I'd chime in again with another video. This was shot at 24p at 1/50, edited at 23.976, and rendered at 23.976.

https://vimeo.com/38299244

Let me know what you think, and if you still see some judder.

SB

Re: GH2 24p Cadence "judder"...
 

Yes, I see the judder your talking about. I would look into the hack I mentioned for the smoother motion and see if that helps some. I usually try to avoid panning as much as possible or I do it really slow.

I remember when I used to export 1280x720 h.264 and upload to vimeo I would get color and motion issues. Someone told me to start using 1280x720 Windows Media Video file output 10k bitrate and I havent
noticed anything weird going on anymore with colors either. I don't know if its due to the way vimeo handles re-compression or what but its worth looking into. Its all I use now and Ive been very happy.

P.S. I am definitely no expert, just my experiences and talking to various people.

Re: GH2 24p Cadence "judder"...
 

Vimeo has converted your 23.976 fps .wmv file to a 30 fps .flv file. The original file does not have judder, but the streaming video has the same judder as before. I don't know why Vimeo is messing with the frame rate. Try uploading a .mp4 file instead.