GH1 Compression Artifacts Test

J

j1clark@ucsd.edu

Veteran
So, here are my examples of how to get 'artifacts' in a video clip. Basically a very quick pan over a 'cluttered' scene. I would probably not use this type of pan for most of my shooting with this camera. There are artifacts in the bushes, but the straight lines of the barn door are more obvious.

The 'pan' is so quick that it would probably not be noticed by the casual observer.

First image from around the 4th second.

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Image from about the 12th second of the clip

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And the video clip:

 
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Do this search in the forums "GH1 mud" and you will see what that is all about. It is not a run around while shooting woods kind of camera.
 
Nitsuj said:
Do this search in the forums "GH1 mud" and you will see what that is all about. It is not a run around while shooting woods kind of camera.
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I didn't find obvious visual examples. There were some number of text posts, but no detailed images and clips.

I gave stills plus a clip to indicate the approximate test situation. With uploaded clips it is sometimes hard to tell what is the original 'artifact from the camera' and what is induced from the upload and streaming site.

I don't plan to shoot 'shakey cam' style, or probably significant numbers of quick pans. So I'm not too worried about these sorts of artifacts. Also, the artifacts didn't 'last' that long after the camera came to some slower motion point, like I think it stablized with in 2 or 3 frames.

I'll have to check such things as cars moving in the back ground, that sort of thing.
 
John Caballero said:
Really? Why wouldn't you?
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Since I'm not planning to use the camera in live events, or the like, such a pan is not something I particularlly like. It sort of reminds me of 70's Kung-Fu movies... along with fast zooms...

But who knows... perhaps there will be some moment where I do want that effect... so I know what it looks like wtih this camera... and I'll probably add some frame blurring in post to cover any 'artifacts'...
 
If you pan slowly and carefully, without yanking the camera it should be alright. It is the sudden whip pan that most produces this. For me 1080p is the only way I am using my GH 1 and I am extremely happy with it.
 
John Caballero said:
If you pan slowly and carefully, without yanking the camera it should be alright. It is the sudden whip pan that most produces this. For me 1080p is the only way I am using my GH 1 and I am extremely happy with it.
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I have no problem using a slow pan. So, I'm pretty sure this 'test' is pretty much way beyond anything I would do.

I'd probably not use a pan much anyway, but I do think of tracking moves, again slowly, so that won't be a problem either.

It's sort of like the redline on the tach... I don't think I've ever come close to it... but I have reved up the engine at some point beyond my usual 2-3000 Rpms... just to test it...

I recall some panning speed table in the American Cinematographer Manual but it has been a very long time since I've looked at that book... so perhaps I'll have to refresh my memory...
(could have also been speed of things transversing the field of view as well... )
 
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The main problem I have, being a wedding videographer, is with photog flashes...they destroy the GH1 codec in huge chunks.

I only shoot from a tripod, so I don't have a huge problem with the whip-pans...I hate shakey video and cut those parts out. Here's a frame from when I was walking around the dance floor moving the camera quickly:

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swyzlstyx said:
The main problem I have, being a wedding videographer, is with photog flashes...they destroy the GH1 codec in huge chunks.

I only shoot from a tripod, so I don't have a huge problem with the whip-pans...I hate shakey video and cut those parts out. Here's a frame from when I was walking around the dance floor moving the camera quickly:
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Maybe you could sell those as 'impressionistic' representations... But I think there was also some slow shutter speed involved as well, since the lights in the back ground were 'streaked'...
 
Good point about the streaking lights.

Yeah it is going to cause you some problems in the woods if it isn't slow steady movements. I have been avoiding the mud fine after putting it through extensive tests, jotting them down in my notebook, and keeping it in mind while I shoot. Just takes practice and knowledge. Good luck.
 
j1clark@ucsd.edu said:
I'd probably not use a pan much anyway, but I do think of tracking moves, again slowly, so that won't be a problem either.
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720/60p is a lot more robust, so if you need to get a faster shot that 1080 can't handle, you can drop to 720 and up-res in post if need be.

It's sort of like the redline on the tach... I don't think I've ever come close to it... but I have reved up the engine at some point beyond my usual 2-3000 Rpms... just to test it...
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Y'know, that's an excellent analogy. It's true that near the redline the GH1 starts to clank and smoke and parts start falling off, but as long as you keep it down to the 2000-3000 rpm range it's silky smooth and luxurious.

I recall some panning speed table in the American Cinematographer Manual but it has been a very long time since I've looked at that book... so perhaps I'll have to refresh my memory...
(could have also been speed of things transversing the field of view as well... )
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Rule of thumb -- for 24p, an object should take about 7 seconds to cross the field of view if you want it to be strobe-free. If you adhere to that strobe-free panning speed, you'll find that the codec issues largely disappear too.
 
j1clark@ucsd.edu said:
...I think there was also some slow shutter speed involved as well, since the lights in the back ground were 'streaked'...
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For sure..slower shutter speeds just compound the codec problems...too much information in those blurry shots. No problem...they're shots you won't find in my videos anyways.

And hopefully none of you indie filmakers have photographers blasting away on set while shooting...because then you WILL get a fail...you lose 6-7 frames to med. This one is from last weekend...on a locked down tripod (no movement). (And if I may stereotype Chinese people, this wedding had 50+ "photographers" blasting away all night. lol I wonder if it had anything to do with my camera's processor locking up AGAIN, and having to take the battery out to turn it off. :tongue:)

"Pro" photog's flash caused the mud, but the light in this scene is from my camera light set to it's lowest setting, AFTER the photog flash:

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swyzlstyx said:
And hopefully none of you indie filmakers have photographers blasting away on set while shooting...because then you WILL get a fail...you lose 6-7 frames to med. This one is from last weekend...on a locked down tripod (no movement). (And if I may stereotype Chinese people, this wedding had 50+ "photographers" blasting away all night. lol I wonder if it had anything to do with my camera's processor locking up AGAIN, and having to take the battery out to turn it off. :tongue:)
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I suppose that this could be covered by faking a 'flash' that is a quick 4-6 frame fade up white fade down overlay, so that the 'flash' looks like a white out, and by the time the flash fades, the image has stabilized again...

Sort of along the motto of 'do it wrong, do it strong'... and often no one will be the wiser...
 
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