GH2 official discussion thread

On the topic of "judder" in HD video, I recommend Michael Brennan's article:
http://www.hd24.com/page4/page15/page28/page28.html

Interesting article, but one statement I don't agree with in this article and I'm certainly no expert on this subject is "The interlace capture or "video look" is associated with live broadcasts and soaps."

Having used the TMV700 extensively with it's 60p output, the end result certainly is a 'video look' despite it's progressive, non-interlaced capture.
 
Sorry, but I think the fact that cinema is actually projected at 48fps debunks the 24p myth.

The 48fps is designed to minimize flicker, not produce smoother motion (which it can't).

Have you ever played 3D computer games? If so, you will know it doesn't much matter that your screen is running at (say) 60Hz, if your graphics card can only render 10fps. The limiting factor, and smoothness of motion, is dictated by the source (ie. footage) frame rate.

The 48fps projection rate is comparable to old CRT monitors. They flickered less at higher refresh rates, but very few programs/games could render at anywhere near those rates. A choppy game is choppy regardless of display rate. Same with video.

If 24fps motion judder was a desirable visual effect
Of course it's desirable (for some), why do you think camera manufacturers go to such lengths to include 24fps modes? Why do you think the GH2 reserves the most bitrate to the 24fps mode? Why do you think Blu-rays distribute movies at 24fps? Is everyone except you crazy?

What looks filmic to me is the motion blur from a 1/48 second shutter speed, combined with narrow depth-of-field to isolate the foreground actors from the background, and projected in progressive frames without the curse of telecined interlaced jitter.
Let's not get sidetracked with interlacing, cinema is progressive. Have you actually shot at 50fps with those settings, and compared to 24fps? If you have and it works for you, great. Nevertheless many people want the 24fps esthetic because this is the way that cinema moves.
 
Sorry, but I think the fact that cinema is actually projected at 48fps

Actually it's 24fps temporal resolution that is extended into 48 times per second, and some systems did it at 72 times. Still, the original material only has a temporal rate of 24 discrete unique frames per second. Camera and projectors that shoot and project true 48fps temporal material looks a lot like pal video temporal feel, just at much much higher resolution. I did work at Showscan years ago that shot 60fps on 65mm film, so this temporal science is nothing new to me...


Pappas
http://www.facebook.com/PappasArts
http://www.pbase.com/Arrfilms
 
Actually I think the articles on this subject have pretty much agreed that 24p is kind of 'outdated' and future audiences may well be seeing productions shot at some other rate as sensors in video cameras become larger.

As far as the GH2's highest bitrate being reserved for 24p is concerned, I think part of that may be due to processing difficulties. Having the highest bitrate reserved for 60i would have been great as far as I'm concerned. But that requires lots of processing power, cooling issues as the result of those greater processing demands and battery life concerns.

I think in the end, what frame rate you prefer is just that, preferences. I'll be using the GH2 more to capture events as opposed to Indie type projects, so for me I'm very happy with 60i, but would have preferred if the 60p capture of the sensor had been the actual output of the camera.
 
The 48fps is designed to minimize flicker, not produce smoother motion (which it can't).

Have you ever played 3D computer games? If so, you will know it doesn't much matter that your screen is running at (say) 60Hz, if your graphics card can only render 10fps. The limiting factor, and smoothness of motion, is dictated by the source (ie. footage) frame rate.
Yes, I understand the difference between flicker and motion judder. What I'm claiming is that at 48fps, flicker is still subliminally perceptible and that it helps obscure the underlying 24fps motion judder. Even telecining at 60i helps obscure it, in spite of how ugly interlacing is otherwise. Your reference to computer graphics displays is not a relevant counter-example because unlike an analog movie projector, a computer monitor does not blacken the screen briefly between each frame.

In fact, the example of computer graphics ties directly into my point about motion blur. Most computer game graphics lack motion blur and need high frame rates to make their crisp details look smooth in motion. I worked in the computer game industry in the 80's and 90's and we tested many combinations of frame rates displayed at different monitor refesh rates. I will never forget what happened when I synchronized a horizontal scrolling game's frame rate precisely with the 60hz refresh rate of an IBM PC CRT monitor. All sense of motion judder vanished. The whole room started to spin whenever I focused on the screen display. It was uncanny and remains one of the most vividly realistic experiences I've had with any type of film or video display.

Have you actually shot at 50fps with those settings, and compared to 24fps? If you have and it works for you, great. Nevertheless many people want the 24fps esthetic because this is the way that cinema moves.
Yes, I have compared 50p, 60p, 30p and 24p videos and I get what you're saying, but here's my counter-example: Try shooting a GH1 at 24p with a 1/250 second shutter speed in broad daylight with a lens stopped down to infinite focus. Then display it in its telecined 60i glory on a large HDTV monitor. There's no 24p magic there for me. To my eyes, it looks more like a high-rez upgrade of a Video-8 Handycam.
 
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I'm no expert in 24p topic, but it was a big issue a few years ago when some tried to encode in 24p using x264 to view on hdtv capable of displaying 24p source at 23.976 fps. They don't make their own contents. they just encode... or transcode. They made it 24p and it looked great on hdtv. Yes they made each frame contains high bit stream data. Before GPU acceleration, it required very high end pc to do playback. Otherwise it would drop frames and jitter. Nowadays sub $200 nettop can play it smoothly. 24p playback is finally cheap. Thanks to GH series, making 24p content is cheap. I think GH13's 24p is great because of the higher bit stream data per frame.
 
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I don't think 24p is myth. But the question is, can GH 13/2 produce good enough 24p content? Does the realtime AVCHD codec do good enough job? I don't know.
 
I have been reviewing GH2 videos posted on Vimeo for the past several days. I am noticing that the majority of them are way underexposed. Is there an issue with the AE on this cam? Its really hard to determine what this cam is capable of even when downloading mts files. The exception is http://vimeo.com/18155086 and a small handful of others.
 
It because lcd is not wysiwyg. Open lcd, looks pretty good, hit record and watch lcd get darker. So with gh2 you have to use lightmeter or zebra or hit record to evaluate exposure.
I have been reviewing GH2 videos posted on Vimeo for the past several days. I am noticing that the majority of them are way underexposed. Is there an issue with the AE on this cam? Its really hard to determine what this cam is capable of even when downloading mts files. The exception is http://vimeo.com/18155086 and a small handful of others.
 
Yes, I understand the difference between flicker and motion judder. What I'm claiming is that at 48fps, flicker is still subliminally perceptible and that it helps obscure the underlying 24fps motion judder/

Maybe in an ultra-subtle way, but not fundamentally. The low frame rate has the biggest effect, because it's still a very choppy way of capturing motion.

Your reference to computer graphics displays is not a relevant counter-example because unlike an analogue movie projector, a computer monitor does not blacken the screen briefly between each frame.
That's true of LCDs - but you'll note I referenced CRT monitors, which indeed go dark between the beam scanning each frame. That's why much higher refresh rates were used with them, to eliminate the flicker. This is essentially identical to film projectors being driven at 48fps.

In fact, the example of computer graphics ties directly into my point about motion blur. Most computer game graphics lack motion blur and need high frame rates to make their crisp details look smooth in motion.
Indeed, but that's a separate issue.

All sense of motion judder vanished. The whole room started to spin whenever I focused on the screen display.
Now we're talking about the judder you get when the display refresh rate doesn't divide perfectly into the source (footage) rate. That's important but not relevant to what we're discussing.

Or maybe you just like 60fps - it is great for games and action-type realism. But it doesn't look like today's cinema, which is what we're discussing. The cinema look is all about not looking hyper-real.

Yes, I have compared 50p, 60p, 30p and 24p videos and I get what you're saying, but here's my counter-example: Try shooting a GH1 at 24p with a 1/250 second shutter speed in broad daylight with a lens stopped down to infinite focus. Then display it in its telecined 60i glory on a large HDTV monitor. There's no 24p magic there for me. To my eyes, it looks more like a high-rez upgrade of a Video-8 Handycam.
Of course, you cannot have a low frame rate AND high shutter speed, as it becomes unwatchable. The missing temporal information from a low frame rate is compensated for by motion blur, the brain can extrapolate motion from it. But that's exactly what I mean - shooting at 24fps and the slow movements it forces on you, coupled with the right amount of blur (from the right shutter speed), gives cinema its look. The shutter speed is important, but so is the frame rate. Changing the rate substantially changes the look.
 
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Hmm... I just found out my 5 years old HDTV doesn't support 1080p24 cinema mode that displays 24p source at 23.976 frames per second. Darn. Nowadays sub $1K hdtv supports the cinema mode. A decent laptops or cheap nettops can do 1080p24 playback with GPU acceleration. Some vdslrs can record in 1080p24. All of those changes took a place fairly recently. I know 24p is very old topic. But has it ever been this easy to handle 24p natively from end to end? It seems 24p is like a gift.
 
about the judder - i watched all my recent footage from GH2 on my projector via popcorn streamer.
it's a different world from my monitor. while the monitor shows an exaggerated unnatural judder,
the projector judder is natural, smooth and almost filmic. so there.
i must find a new monitor that support this 24p for editing and watching more fluently.
any ideas?
 
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The "film look" is actually 48fps!
Absolutely not true. The "film look" is 24fps.

People have been confusing the flashing-a-frame-twice with "48fps" for years, but it's simply not true. The film runs through the projector at 24 frames per second. 90 feet of film per minute. There is no possible way, by showing the same frame twice, to simulate 48fps. It is not, was not, has not, and will not, ever ever ever be, 48fps display.

What they do is flash the frame twice to reduce the amount of time the shutter is closed, and therefore reduce the amount of flicker in whites. But it has nothing, nothing, nothing, nothing do do with motion rendition. What you see on the screen is 24fps motion. Period.
 
The other major factor is the 1/48th second shutter speed, which determines how much motion blur is seen during panning and object motion. I suspect this is far more important in creating a filmic look than the underlying frame rate.
I have owned maybe three dozen film cameras in my days, maybe four dozen. I think I can count on the fingers of one hand, the number of them that exposed their film at 1/48. People repeat 1/48 as if it's gospel, when in actuality it isn't even that widespread. 180 degrees is not sacred. I've got (or had) film cameras dating back to the 1920's (B&H Eyemo) and 1940's (B&H Filmo), lots of Super8 cameras, I've got three CP16-series cameras right now (two CP16/R's and a GSMO), I've had Eclairs and Konvases and Beaulieu R16's and Krasnogorsk K3's and ... well, a lot. And there are two common things between them:
1) they all shoot footage that looks like film
2) none of them have a 180-degree shutter.

They range from 150 degrees (the Konvas 35mm and Eyemo) to 240 degrees (the Filmo). The CP's are 144, 156, and 170 degrees. The Super8 cameras ranged from 90 (90!) degrees on my Beaulieu 6008PRO (144 degrees in "low light" mode) up to 220 degrees for the "XL" cameras like the Elmo 1012XL-s or Canon 1014XL-s.

I contend that 180-degrees is the single least important factor in attaining the film look, and furthermore that it is damaging to DSLR/CMOS shooters because it leaves them choosing 1/50th shutter in scenarios where that will result in rolling bands in their footage, when if they just chose 1/60th they'd get perfectly filmlike footage, but avoid the bands.

I further contend that the 24fps frame rate is far and away the #1 most important factor in making something look like it was shot on film, rather than on video. Far and away. Note: we're not talking about making something look like it was a major hollywood production, that involves lighting and production design and all that. I'm talking about making it look like the capture medium was film, or video.

It's really so simple to test. Get a DVX100. Shoot a scene at 60i, with 1/60th shutter. Then shoot the exact same scene at 24p, with a 1/60th shutter. One will look a whole lot more filmlike than the other. It's night and day different.
 
What I'm claiming is that at 48fps, flicker is still subliminally perceptible and that it helps obscure the underlying 24fps motion judder.
Well, that's an interesting angle. I'd have to think about that one... seems easy enough to test. Shoot something on a 24p video camera, and transfer the resulting footage to film. Watch it projected from film (with the 2x or 3x flashing of the frames) and compare that to the footage played back via 24PsF on a 24p-capable monitor. If there's a difference in motion judder, then your theory is validated. If there isn't, then it isn't.

Try shooting a GH1 at 24p with a 1/250 second shutter speed in broad daylight with a lens stopped down to infinite focus. Then display it in its telecined 60i glory on a large HDTV monitor. There's no 24p magic there for me.
True, but the exact same thing would happen if you shot a film camera at a 45-degree shutter angle with infinite focus. And you can see examples of that; watch the beach-storming scene of Saving Private Ryan. Doesn't look like video at all, but it does look different from normal film.
 
Guys, the below clip is 100% indicative of why I just don't get the 24p thing. The stutter motion I see exists on both on my LCD computer monitor as well as my 60" Pioneer Kuro plasma. I've even tried different motion settings on the Pioneer and they all look s-t-u-t-t-e-r-y.

The clip was shot in 24p cinema mode, at the highest quality and with a shutter speed of 1/60. I also tried 1/50 and there was no difference in the degree of stutter.

In all honesty, this kind of motion would give me a headache in minutes.

http://vimeo.com/18394238
 
Ken, i don't know what to tell you..
panning causes the stutter to be extreme..
+ you are extra sensitive to this. (i have to tell you the truth, for me it looks reasonable, and it exist on most of the GH2 footage i've seen also
on vimeo)

Barry, please put an end to this judder/stutter 24p debate that causes Ken all this misery (watch his clip and tell as your verdict please) :)
 
Roei, I guess the things that drives me nuts is that I do see panning (at about the same speed I used) on other 24p clips and don't see this degree of stutter. Of course I don't know what, if anything, was done to these clips in post since most are not available as native m2t clips. Perhaps something is done in post that removes some of the judder.

Roei, if you can, would you direct me to another clip that you feel shows this degree of stutter? Thanks much!
 
Ken, first of all, Larry's footage with the boats has the exact stutter, only he used some kind of slow panning and fluid motion, but it's the same as yours.
the basket ball footage is so shaky that you can't really tell the difference, but it's also there for my opinion.
i'll have a look, but rest assured your stutter is very much the same as every original GH2 MTS you'll be able to download.
search around on those latest GH2 vimeo tests everybody adds each day. i see stutter on most of them (look for panning or movement such as yours and judge) - i would also try asking around for an answer on how those MTS clips would look the most fluid on a certain monitor.
(maybe MTS originals get interpreted differently than most of those quicktime exports)
 
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Guys, the below clip is 100% indicative of why I just don't get the 24p thing. The stutter motion I see exists on both on my LCD computer monitor as well as my 60" Pioneer Kuro plasma. I've even tried different motion settings on the Pioneer and they all look s-t-u-t-t-e-r-y.

I suspect a lot of you who see this problem with footage with relatively slow motion (as your pan is) are actually having codec issues, and/or an underpowered CPU, resulting in dropped frames during playback. Or if you're viewing online, you're not getting a smooth download, resulting in missing frames.

The Vimeo footage you linked plays fine here on my quad-core PC. There is a very very sutble judder that comes from using 24fps - but it is barely noticeable unless you know what to look for. If you are seeing major judder or jerks then it's something else on your system.

EDIT: Correction, each time I play it back it does occasionally stutter, but in random places. The randomness indicates it's a playback issue. Also one of my CPU cores is maxed out, so this is likely a CPU overload problem with Flash (which I think Vimeo use to play video). It doesn't seem to happen fullscreen (or maybe it's just dumb luck).
 
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