GH2 Weird pixelation issue...

HotConductor

HotConductor

Well-known member
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Here are two screen raw frames of some footage I shot with my GH2. It was shot in manual mode, 1080p24fps. Notice that one frame looks smooth, and the other contains TONS of what appear to be compression artifacts.. I am new to the GH2 and wondering if this is common... Is there a solution?

No grading of ANY kind. Just raw captures btw. BTW, I always shoot on SanDisk Extreme II, class 6 cards, and have used the cards in other cameras (HMC150) without issue.
 
I'd guess it's just more than the codec of the GH2 can handle. Water is tough. Everything is always moving constantly.

Solution? Possibly the GH2 hack coming out... you will eventually be able to up the bit rate of the codec so you can capture things like this without pixelation... hopefuly :p
 
HotConductor said:
Here are two screen raw frames of some footage I shot with my GH2. It was shot in manual mode, 1080p24fps. Notice that one frame looks smooth, and the other contains TONS of what appear to be compression artifacts.. I am new to the GH2 and wondering if this is common... Is there a solution?

No grading of ANY kind. Just raw captures btw. BTW, I always shoot on SanDisk Extreme II, class 6 cards, and have used the cards in other cameras (HMC150) without issue.
Click to expand...

How does the clip look when played back?
 
Where you panning with the subject and hand held for this shot?

It looks like codec break up when there's excessive data to handle - the GH1 did this & it was called mud... but you'd only really see it when you stresed the codec by going from dark to light or low detail to high detail within a frame. The GH1 hack cured this (mostly) by forcing the codec to higher bit-rates.

The incoming GH2 hack will do the same, I'd imagine. Although I've not seen many codec break up on the GH2... you might just have found a new 'stress test' for the hack... hand held & following a swimmer in a pool with lots of reflections :)
 
I think you are spot on regarding the codec. A pool of constantly moving water is pretty extreme movement. Still, I'm very surprised to see artifacting from one frame to another. The next 2 frames were clean, then another with blocky pixels everywhere. Very very strange to me..

I don't see a thread or any info on the GH2 hack... Did I miss a crucial thread? Thought I did a search for that last week with no success... BUT, I'm looking forward to it! I have a feeling I will hack it, provided that I can revert back if needed. I love the camera and don't want to ruin it in order to do cool stuff. I do love jailbreaking devices though. Droid X... Xbox... Just not very big on an expensive camera.
 
HotConductor said:
I think you are spot on regarding the codec. A pool of constantly moving water is pretty extreme movement. Still, I'm very surprised to see artifacting from one frame to another. The next 2 frames were clean, then another with blocky pixels everywhere. Very very strange to me..

I don't see a thread or any info on the GH2 hack... Did I miss a crucial thread? Thought I did a search for that last week with no success... BUT, I'm looking forward to it! I have a feeling I will hack it, provided that I can revert back if needed. I love the camera and don't want to ruin it in order to do cool stuff. I do love jailbreaking devices though. Droid X... Xbox... Just not very big on an expensive camera.
Click to expand...

http://www.dvxuser.com/V6/showthread.php?254811-PTool-with-GH2-support-released
 
TheDingo said:
Looks more like bad de-interlacing than compression artifacts. You definitely shot in 24P mode, and your NLE was also set to 24P mode too ?
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There is NO de-interlacing going on. I shot in 24p, project settings are identical to the original files. 1080p24fps. I NEVER shoot interlaced. NEVER edit interlaced. Here are two more frames..
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HotConductor said:
View attachment 36302View attachment 36303
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Here are two screen raw frames of some footage I shot with my GH2. It was shot in manual mode, 1080p24fps. Notice that one frame looks smooth, and the other contains TONS of what appear to be compression artifacts.. I am new to the GH2 and wondering if this is common... Is there a solution?

No grading of ANY kind. Just raw captures btw. BTW, I always shoot on SanDisk Extreme II, class 6 cards, and have used the cards in other cameras (HMC150) without issue.
Click to expand...
hmm weird, maybe some encoding problem?
 
I´v got similar stuff, but in my case the whole dark areas looks like "super compressed" with lots of artifacts and pixelation using low ISO in 24p mode.
I will upload a pic in a couple minutes.
 
Because that's how AVCHD works. it's not recording each frame "completely." It records keyframes, and then only encodes the difference between the first and second keyframe. It's only got 24mbps to go around, so if it uses it up too quickly, the codec will breakdown. (This is a fairly simple explanation of AVCHD... it's surely much more complicated than this.)

This happened far more often in the 1080p mode of an unhacked GH1, because it was only a 17mbps iteration of AVCHD.

Deep focus, highly detailed, constantly moving water is tough for the codec. I took my 17mbps GH1 and put the 40mbps hack on it. I didn't have a problem since.

If you need scenes like this, I'd encourage you to wait for the hack on the GH2 to develop, shoot with shallower depth of field if possible (less detail to record), or move to a different camera (one that perhaps doesn't use a fairly consumer grade iteration of the AVCHD codec.
 
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