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50Mbit 1080p MJPEG on the Panasonic GH1


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#1 Karel Bata

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Posted 12 June 2010 - 05:45 AM

This is interesting in several ways.

A hacker with the tag of 'Tester 13' (why the secrecy?) has managed to hack the GH1 to run at 50Mbit/sec. Isn't that better than the 5D MkII? :blink: They'll have to go and do all those Zacuto tests again! :lol:

http://vimeo.com/12472000



article: http://bit.ly/aMmsWx

Posted Image

Panasonic must have mixed feelings about this. They're morphing the GH1 into the AG-100 later this year at four times the price, without lens, but at only 24Mbits/second!

I do like the form factor. That's a funky little camera. Not sure I'm too keen on how it handles the highlights, but hey! - it's less than £1,000!

Of particular interest is that (I believe) this is four thirds format, which must surely mean that you can use all those old, and really very nice, TV lenses. Am I right? Which means you get proper focus control, which gives it a real edge over the Canon 5D. And anyway, some of us feel the 5D's chip is maybe a litter bigger than we actually need...

Nice. What next..? :D
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#2 Karel Bata

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Posted 12 June 2010 - 05:53 AM

Oh, and it's not H264!

:D
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#3 Phil Rhodes

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Posted 12 June 2010 - 06:50 AM

Don't grin that widely - h.264 is capable of doing far better for the bitrate than MJPEG.

Whether it actually does or not is application-specific.

P
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#4 Tim Carroll

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Posted 12 June 2010 - 09:27 PM

Don't grin that widely - h.264 is capable of doing far better for the bitrate than MJPEG.

Whether it actually does or not is application-specific.

P


Just started playing around with the different patch settings that tester13 developed. Wrote more about this under the Panasonic section of HD. But just to throw this out, with the unmodified camera, with the Panasonic stock 1.32 firmware, shooting a scene with foliage in 1080p (with 60i wrapper) AVCHD, I was hitting a bit rate of up to 15Mb/sec. After patching the firmware, and setting the patch at the lowest level (as I have class 4 SDHC cards which can be rather slow), shooting the same scene with foliage in 1080p (no wrapper, actual 23.98 fps) AVCHD, I was hitting a bit rate of up to 33Mb/sec. And there are higher level patch settings which are working for folks with faster class 10 SDHC cards. So I think we may be able to get much more out of the camera than it had when it left the factory.

Best,
-Tim
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#5 Karel Bata

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Posted 13 June 2010 - 04:46 AM

What does a particular bit rate translate into? Like, what's the equiv of 16 or 35mm?

I liked the look of the GH1 when it was first released. Nice price with a compact size, but the video was disappointing. Great for taking on breaks, but on the pro video front, kind of an 'also ran'. But this hack rather changes things.

Of more interest is how this will affect what manufacturers do. How many actually welcome their firmware being hacked and future camera releases looking tame, even intentionally compromised?
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#6 Tim Carroll

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Posted 14 June 2010 - 07:21 PM

Just shot some 73.89 mbit/sec MJPEG footage with my patched GH1. It's really pretty. Looks better than the AVCHD footage. Only drawback is that it is 30P, which makes it not cut real well in an FCP timeline.

Best,
-Tim
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#7 David Bowsky

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Posted 15 June 2010 - 01:20 AM

Fascinating. I've been waiting for the folks behind CHDK to start fiddling with the Canon SLR line, but looks like "Tester13," whoever that is, beat them to it. Not familiar with MJPEG, although in the vimeo clip I didn't see as much of the aliasing (line skipping?) effect as on the 5d/7d/550d footage I've watched. I may have missed it though.
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#8 Karel Bata

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Posted 15 June 2010 - 03:03 AM

Just shot some 73.89 mbit/sec MJPEG footage with my patched GH1. It's really pretty. Looks better than the AVCHD footage. Only drawback is that it is 30P, which makes it not cut real well in an FCP timeline.

Give it a couple on months and the hackers might fix that. Hopefully Panasonic will get in on the game, like Canon did. On the other hand they may not like the way this makes the AG-100 look. Or maybe that will get hacked too. Now that would be nice! A properly laid out camera with decent performance at a nice price. :D

Care to post your footage?
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#9 Tim Carroll

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Posted 15 June 2010 - 06:16 AM

On the other hand they may not like the way this makes the AG-100 look. Or maybe that will get hacked too. Now that would be nice! A properly laid out camera with decent performance at a nice price. :D

Care to post your footage?


Got the Hot Rod Adapter on the GH1 and I really like the way it's laid out now. And I LOVE the live view viewfinder and the focus assist on the GH1, along with the fully manual movie mode. Not sure that will be part of the AG-100.

Will try to post some footage soon, just trying to find a way to compress it enough for the web, without losing the image quality, which is what I'm trying to show.

Best,
-Tim
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#10 Tim Carroll

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Posted 15 June 2010 - 08:50 AM

Okay, here is a clip from some of the MJPEG footage I've been shooting with the GH1. This is foliage, not too dense, but the details in foliage can really tax the whole firmware, compression, output system on the camera.

The original footage is 1920 x 1080 at 30P (actually shot squeezed at 1280 x 1080 30P) and the capture bit rate was 73.89 mbits/sec. Unfortunately that is WAY too big for posting on the web, so I had to compress the footage to make it manageable. This clip is 848 x 480 at 15P and with a bit rate of 11 mbits/sec. So some detail is lost and some blocking is taking place, but it's minimal.

The clip is about 10MB so give it time to load, and it is in the Apple MJPEG A codec.

What I think demonstrates the improvements the patches create in the firmware is how the foliage comes into focus in the last half of the clip. From blurry to sharp, and in the original, there was no blocking in the foliage when it was out of focus, and it just "naturally" became sharper as it came into focus.

MJPEG clip shot with tester13's patches to the GH1 firmware

Best,
-Tim
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#11 Karel Bata

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Posted 15 June 2010 - 09:49 AM

Looking very nice for such a cheap camera. I can see why you're excited! Can't tell if you're getting that infamous shearing artefact, but in theory it should be less pronounced than on the Canon. That road looks a bit burnt out. Are you shooting in the direction of an overcast sun?

And was that with the lens that comes with the camera..? How does that fare? Three fourths has a good pedigree, but have they cut corners?

Obviously you'd need separate sound for shooting dialog, but what's it like for ambient sound? It's also supposed to have a quiet zoom. So does it..?

Sorry to be a nuisance... ;)
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#12 Tim Carroll

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Posted 15 June 2010 - 10:10 AM

Don't use the stock lens at all. Have a Hot Rod PL adapter and use my Cooke Speed Panchro lenses. Not sure how the stock lens performs.

Camera has audio, but I always use a separate digital field recorder with good mics for sound.

That was a grab shot last night as the sun was setting behind me on an overcast evening.

Best,
-Tim
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#13 Karel Bata

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Posted 17 June 2010 - 03:21 AM

Philip Bloom posted a review of the hacked GH1 http://bit.ly/BloomGH1

"It’s better looking than the 5D Mark II’s H.264 and less compressed...

"The image is smoother looking and better scaled from the 12MP CMOS compared to the 5D Mark II which has 22MP to deal with."


You must be grinning from ear to ear Tim! :D

Time to put those 5Ds on eBay...
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#14 Chris Durham

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Posted 17 June 2010 - 08:48 AM

It's a very nice image, but it doesn't seem to have a lot of range. The Zacuto comparisons showed how contrasty the G1 image is and this doesn't change that of course, but downsampling rather than line-skipping makes a huge difference.
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#15 Tim Carroll

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Posted 17 June 2010 - 01:03 PM

It's a very nice image, but it doesn't seem to have a lot of range. The Zacuto comparisons showed how contrasty the G1 image is and this doesn't change that of course, but downsampling rather than line-skipping makes a huge difference.


Chris, you lost me there. That MJPEG clip I posted is straight from the camera, of a scene shot on an overcast evening. What kind of range would you expect from that lighting?

And I certainly wouldn't call it "contrasty". If you do feel it has too much contrast, that can be dialed down in camera, or, because the new image is much "fatter" than what previously came out of the camera, you can do alot with it in post.

Best,
-Tim
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#16 Chris Durham

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Posted 17 June 2010 - 01:50 PM

Of course I'm not viewing this on the greatest monitor so that could account for something. But if I were comparing this to the Zacuto comparison, I recall the shots with the light bulb where the Canons maintained details in the bulb but the GH1 went to white. And here you have:

Posted Image

Hot spots in the light clipping while not seeing a lot of detail in the darks either. So this shot isn't exposed for what's in the shadows but is blowing out in the highlights.

Don't get me wrong. I really like what I see here. I took another look at it before responding here, this time at full screen, and it really is quite impressive. As far as saying the image is contrasty, that's not really a criticism - I quite like it. As far as evaluating the dynamic range of the image though, it doesn't offer very much. It's an obviously overcast day and most of what I see is in the middle as far as exposure. Where it's dark there's not much detail. In the few places where there's a lot of light there's not much detail.
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#17 Tim Carroll

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Posted 17 June 2010 - 03:35 PM

Okay Chris, just so we're on the same page, we are both talking about the clip I posted earlier in this thread, right? We are not talking about the clip that you did a frame grab from above, right, because I have no idea where that clip came from.

We're talking about the yellow flowers with the green grass background, correct?

Again, that was a grab shot as I walked out my front door, on an overcast evening. No attempt to balance light or anything else. Just to see if the camera would capture a high bitrate MJPEG with no blocking and if I could get soft out of focus that would not block up, and come from soft out of focus to sharp in focus in a gradual manner, with no blocking or pixelating along the way. And the clip I posted unfortunately had to be compressed from the original, so a few artifacts were added. But I think the footage looks remarkable, especially when you know it is coming from an $1100 camera.

Sure, it ain't film, but what is. And the results I got shooting AVCHD 1080 look quite similar. After L&T into FCP as ProRess 422 (HQ) and JES Deinterlacing, that AVCHD footage drops right onto an FCP timeline. You can also make adjustments in camera, like gamma, brightness, sharpening, color, etc. and the footage is "fat" enough to manipulate in post.

It might not be your cup of tea, and that's fine. I just think it's pretty amazing and I can definitely see using it instead of Super 16 on projects.

Best,
-Tim
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#18 Chris Durham

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Posted 17 June 2010 - 03:56 PM

Good to see we weren't on the same page because I was a bit confused Tim. The grab I posted was from the post on Philip Bloom's blog that Karel linked. And you're right, it's vastly different from what you posted, both in terms of contrast and lighting conditions. So yeah, my comments were all about dynamic range. As far as the quality of the image I think it's superb - I actually went peeking around Hotrod Camera's site after watching these. As far as the compression and artifacting - and aliasing I'm sure - This is looking superior to the 5D no doubt. I'm deeply ambivalent and love/hatey about these HDSLRs, but this development is definitely another point in their favor.

At the end of the day though, the GH1 probably isn't the camera for me. I can't really afford the Hotrod mod - and definitely not the PL glass on top of it - and I'm not happy with the limited lens options for the format (especially since I prefer not shooting with zooms).
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#19 Karel Bata

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Posted 17 June 2010 - 03:56 PM

I think the image from the GH1 is truly impressive for that price bracket. But I've been hunting around, and though there's not a lot of stuff from this hack up on the net yet, what I've seen does indeed show up some limitations:

http://www.youtube.com/watch?v=pe6kpYbFAMU

Not a lot to go on, but what's noticeable to anyone who's been following the DSLR 'revolution' is the lack of the infamous shearing - that vertical looks solid to me. Looks nice overall - for what it is! :lol: Great on detail. But look at that blue area when the camera pans to the right at 36". What I think should be a smooth gradation isn't.

Here's a video on Vimeo (which won't embed here, and maybe you need to log in). Rich colors. But the blacks tend to take a nosedive, and the highlights burnt out. Worse, areas of what should be gradual shading, like the sky, look noticeably blocky. A shame. Otherwise it has a really nice look to it - if that's the look you want. Going back to the video I posted a link to above I can now see how all the problem areas have been skilfully avoided. I'm now rather suspicious about its origins. Tester 13 is not methinks some run of the mill hacker.

Still, it's a very nice camera for it's price, and for the emerging film-maker on a budget is a good tool with which to get into that mind-set of working around limitations - things are often too easy for the beginner these days, I say.

The GH2 is imminent, about which I'm very curious.

Edited by Karel Bata, 17 June 2010 - 03:58 PM.

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#20 Chris Durham

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Posted 17 June 2010 - 04:22 PM

What's interesting to me is that this can be done through a hack. It's also interesting in that it probably exposes why Canon went with line skipping. The GH1 is 12.1 megapixels and it can pull this stunt, but apparently sometimes has problems at 50Mbps. So I can see why the 5D, with 9 million more pixels, might have a hard time downsampling. I'm still very curious to see what Nikon does next. Their cameras don't seem to be as pixel crazy as Canon. Some people are speculating RAW files as the next step for HDSLRs, but the problem is there's not a post workflow for that - unless you go CinemaDNG which I'm all for. I think they should keep the pixel count low, up the dynamic range (easier with larger pixels), and pump up the bit depth.
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