Press Release: Panasonic Announces 4K Mirrorless DMC-GH4

[Kent Karlsson]

Originally Posted by Noa Put

Not sure if this has been mentioned here already but on vimeo, see video below (check out the 4k downloadable file) the creator of the video confirms that the screen info doesn't disappear anymore like on the gh3,

GH4 first 4K shots in Paris (Pre Serial Camera with Beta Firmware) on Vimeo

Downloaded the source file, but it was choppy playback on my edit system (Intel i5, Vegas pro)
I have tried other 4K source files and they played smooth , is it different codecs or what ?
Footage looked soft...

[Noa Put]

Originally Posted by Adam Letch

also they didn't incorporate the internal image stabilization which they have on the GX7.

The gx7 has only inbuilt stabilization in stills mode, not video, so that's useless for us videoshooters, the GH4 is definitely a step up from the gh3 but I"m actually not that overly excited, not for a camera that's almost twice the price of a gh3. It is still very cheap for a 4k capable camera but to me the main revolutionary feature is 4k, if you need it. All the rest is just a evolution of what was already good and made better. There are 2 things that would have made this a killer camera which are both missing 1. a build in nd filter and 2. inbuild camera stabilization, like the Olympus OMD series has, but I guess there is some kind of understanding between Panasonic and Olympus not to step on eachother turf that will make this addition impossible.

The brick will be only useful in studio environments and a 4:2:2 capable external recorder and battery solution will add a lot more in cost then what the body only will set you back + that won't be a portable solution anymore, the guys from Zacuto will probably have a blast modding this camera so at the end you"ll end up with a 10k camera all included, if you love zacuto anyway :)

What I"m most interested in is how clean it shoots at very high iso's compared to the gh3 because that has not been shown yet, if it could do a very clean 6400 iso that would be a big plus if you'd go for the body only, the copping ability when editing 4k in a 1080p project is this as well but looking at the camerastore review where they show this I get the impression you loose out on sharpness, same for the 96fps sample they showed, something did not look right there, might be the youtube compression so not sure about that.

Also the dynamic range in that first shot where he is standing in the water with the snow on the left shows a lot of blown highlights, this is ofcourse a high contrast scene most camera's will struggle with but it looks to me this has not improved over the gh3, but nevertheless is still good.

It also looks like the inbuild audio is still of the same crap level as the gh3 as there is no mention of improvement on this meaning you still need to add on an external mike.

Maybe I did not understand this right but what does he mean with "the interface disappears immediately"? : (can be found back at 12:22 on the camerastore video)

[Noa Put]

Originally Posted by Kent Karlsson

I have tried other 4K source files and they played smooth , is it different codecs or what ?

On my edius 7 it looked like it was playing in realtime but I could hear the audio stuttering so it wasn't.

[Ken Ross]

Noa, I noticed the same thing when I dropped the Paris video in to Edius 7. But when I looked closer, the audio stuttering was also accompanied by a more subtle stuttering in the video. It does seem to be taxing the computer.

[Kent Karlsson]

Originally Posted by Kent Karlsson

Downloaded the source file, but it was choppy playback on my edit system (Intel i5, Vegas pro)
I have tried other 4K source files and they played smooth , is it different codecs or what ?
Footage looked soft...

After some reading i suspect different compression is the cause , All-I vs IPB.
All-I is less compressed and needs less processor power for smooth playback i have read.
Can anyone confirm this ?

[Tony Tibbetts]

What's interesting about the Zacuto video is that between roughly 9:50 and 10:00 he claims the camera can output 4K though the mini-hdmi port on the camera. I hadn't hear this before now.

[Noa Put]

Now they still to develop a recorder that can deal with that, but yeah, if that will be the case you could bypass that brick and go straight to a external recorder.

[Eddie Yamashita]

i'm actually more excited about this zacuto zoom control handle mentioned in the video than anything else..

[Noa Put]

I would expect a price on that that would surpass the gh4 body price.

[Eddie Yamashita]

wow, really? i was hoping for something in the neighborhood of 300 USD..

[Noa Put]

Well, i m Just guessing, bit if you know zacuto you know it won't be cheap

[Phil Lee]

Hi

Originally Posted by Kent Karlsson

After some reading i suspect different compression is the cause , All-I vs IPB.
All-I is less compressed and needs less processor power for smooth playback i have read.
Can anyone confirm this ?

Yes All Intra is essentially a series of stand alone jpeg images, and each frame is independent and so much easier for editing.

The problem is All Intra is much less efficient when compressing. For example if the GH4 was all Intra frames at 100Mbits/sec at 24fps in 4K, that means each frame has to be compressed to around 500KBytes. Take a photograph that is around 4K resolution and compress it down to a Jpeg at 500KBytes, it is going to lose a lot of detail! So you need much higher data-rates for all Intra frames. The GH4 will compress at 200Mbits/sec for 60fps HD in all Intra, so each frame has to be compressed to around 410KBytes, but of course for an image of 1920x1080 pixels, that isn't too bad. Each frame is also very consistent in quality with all Intra.

What these cameras are recording though is long GOP in 4K to achieve better compression, so essentially you start with one Intra frame with a much healthier file size and image quality, and each frame after is described based on the differences from that first frame, in other words, a description of what has changed only, this tends to work well as each frame is often not that different from the one before. It can be like Chinese whispers though, so by the time 24 frames have gone past, frame 24 may not look that good and quality can be inconsistent between frames. Fast action is very challenging and quality can quickly take a dive.

For even better compression efficiency, the encoder can not only describe the differences from the past frame, but from a future frame as well. This makes editing quite a challenge for an editor as when we select a frame, it will need to read back and forward in time to collect up all the data to recreate the single frame we've selected.

The other issue is hardware acceleration, this may be available from the graphics card/driver for HD resolutions, but not supported for 4K resolutions.

Regards

Phil

[Phil Lee]

Hi

Originally Posted by Kent Karlsson

Downloaded the source file, but it was choppy playback on my edit system (Intel i5, Vegas pro)
I have tried other 4K source files and they played smooth , is it different codecs or what ?
Footage looked soft...

I think it is how it has been encoded, also it is 25fps so depending on your project settings Vegas may be frame doubling to 50fps which will be stressing it some more. It plays well though in VLC.

Unfortunately I find the clip lacks detail, looks good downscaled to 1080P (as all 4K does) but at 4K it lacks any real detail, however this isn't a file directly from the camera, and is only encoded at 47Mbits/sec average bit rate, so here is hoping the original footage has a lot more detail befitting of its 4K status.

Regards

Phil

[Kent Karlsson]

Originally Posted by Phil Lee

Hi



Yes All Intra is essentially a series of stand alone jpeg images, and each frame is independent and so much easier for editing.

The problem is All Intra is much less efficient when compressing. For example if the GH4 was all Intra frames at 100Mbits/sec at 24fps in 4K, that means each frame has to be compressed to around 500KBytes. Take a photograph that is around 4K resolution and compress it down to a Jpeg at 500KBytes, it is going to lose a lot of detail! So you need much higher data-rates for all Intra frames. The GH4 will compress at 200Mbits/sec for 60fps HD in all Intra, so each frame has to be compressed to around 410KBytes, but of course for an image of 1920x1080 pixels, that isn't too bad. Each frame is also very consistent in quality with all Intra.

What these cameras are recording though is long GOP in 4K to achieve better compression, so essentially you start with one Intra frame with a much healthier file size and image quality, and each frame after is described based on the differences from that first frame, in other words, a description of what has changed only, this tends to work well as each frame is often not that different from the one before. It can be like Chinese whispers though, so by the time 24 frames have gone past, frame 24 may not look that good and quality can be inconsistent between frames. Fast action is very challenging and quality can quickly take a dive.

For even better compression efficiency, the encoder can not only describe the differences from the past frame, but from a future frame as well. This makes editing quite a challenge for an editor as when we select a frame, it will need to read back and forward in time to collect up all the data to recreate the single frame we've selected.

The other issue is hardware acceleration, this may be available from the graphics card/driver for HD resolutions, but not supported for 4K resolutions.

Regards

Phil

Thank's for clarifying !

[Paulo Teixeira]

Yes, that isn't a native file and I heard he shot it at f/16! You're not going to get the best 4K quality possible with that setting. Perhaps he should have increased the shutter a little bit more and it would have looked better. One thing for sure is that he didn't use an ND filter which would have allowed you to use the best Shutter and Aperture setting.