GH4 4K Panasonic video camera, official topic

Vitaliy_Kiselev

Maybe Im thinking about this incorrectly, but shouldnt the GH4 have higher bitrates to keep the 4k footage at the same quality as the FHD from the GH3?

We talked about it, many pages ago :-)

To be short, if you up the resolution and/or up framerate you can compress things much more efficiently, so bitrate can be lower than just linear extrapolation. Due to better prediction.

Of course, if you start shooting extremely detailed things with very complex motion (like fast water stream), you need all that is possible. But in real life all will be fine.

joethepro

@Vitaliy_Kiselev Thanks for the explanation, I was unaware of that!

driftwood

Found a use for my old Atomos Ninja 1 whilst testing the GH4 - it happily records downscaled thru the hdmi out 4K files to 1080 4:2:2 8-bit/10-bit Pro Res 422/LT/HQ Files - GH4 HDMI display off - instantly works at 1080p24 without problems. I'll try and get a few results up soon.

itimjim

Hey @driftwood I thought LT on the Atomos Ninja was 10-bit?

driftwood

It does either: 4:2:2 8-bit or 10-bit out thru HDMI switchable on GH4 to Atomos Ninja 422/LT or HQ. Incidentally, and apologies but off topic, if anyone wants this Ninja + two drives 250Gb & 500Gb Hitachis) cheap - let me know via pm and make me an offer!

Ian_T

@driftwood, not sure if you could do this but a good test would be for one to shoot using the Ninja out of the GH-4 to get 4:2:2 10 bit 1080p vs recording 4:2:2 10bit 4K and down-converting in post with an NLE. If the image looks exactly the same then using the Ninja would be the best way (on the cheap) to finish in Full HD. Then again you'd need one of those new expensive 4k recorders to actually do the tests.

Aria

@driftwood, To be honest i'm shocked that the Ninja 1 can take the 4k and downscale on the fly to 1080. That's kind of amazing to me. I don't understand how it's doing it, but hey if it can do it, who cares? I hope you can post some images from the Ninja footage to show what it looks like. This sound promising for those who just want great 1080.

AdamT

@Aria I believe the GH4 downscales 4K to 1080 before passing it through the HDMI out port. As far as the Ninja knows it's just getting an ordinary 1080 signal.

But as someone pointed out at the place who's name shall not be spoken, the key question is how the camera is doing the downsampling. Is it actual downsampling as the A7S seems to do in camera, or is it pixel binning or line skipping. If it's not actual downsampling then there's probably no reason to record 4K internally.

The other question is, is it actually putting out 10 bit data, or since the 4K is recording 8 bit to the card, is it simply putting out 8 bits of data in a 10 bit container?

mrbill

@driftwood - does this mean you have to have the LCD screen turned off when downscaling from 4k to 10 bit 422 1080 thru the hdmi out? Thanks very much.

Vitaliy_Kiselev

Vitaliy_Kiselev

http://akihabaranews.com/2014/04/10/article-en/review-panasonic-lumix-gh4-1965892312

driftwood

As I said earlier its 4K down convert in-camera NOT the Ninja doing it.

@mrbill Nope. See images 'INFO DISPLAY = Off'

mrbill

so clean feed with on screen display info off - thanks!

mrbill

@driftwood - better 1080p feeding the ninja 10 bit downconvert from 4k, or setting the GH4 to say 200mbps 1080p and 10 bit output? Sorry if you haven't got round to comparing these..

driftwood

We're doing a load of tests over the next three days here at Driftwood Productions.

Someone asked a EX Tele question a few pages back: Answer: Ex Tele only goes to 60fps in Variable Frame Rate.

@AdamT You can't record to card in 10-bit mode remember - only 8 bit 4:2:0.

You can record in-camera 8-bit 4:2:0 and select an output of 422 8-bit thru hdmi and record externally at the same time. 10-bit 422 mode output/record is thru HDMI only.

I'll be testing the YAGH's passthru too.

Record the 3x over HDMI !

sammy

@driftwood , I heard from a couple people that the 96fps is not all that in terms of image (1080p) compared to 60p (1080p) , is that correct? how would you compare it to the quality of 1080p (from internal 4k 24p), thanks

arum

@driftwood, does the 1080p mode have the same crop (x2.3 was it?) as the 4K, or does internal 1080p use more sensor and have a "standard m43" x2 crop?

Tron

I agree on the 96 fps, the footage I've seen thus far appears to look more like upconverted 720P. Not necessarily bad, but not as solid as 1080P mode either.

Vitaliy_Kiselev

Some source video files from GH4 - http://exformers.kylos.pl/gh4/

heradicattor

Very interesting! Some description about what is each file? (recording mode, lens, other settings)

driftwood

Le Cas GH4 from Driftwood (GH4 De-mobbed) coming soon :-)

olli66

anyone knows if the battery will be a new model or can I use the ones from my gh3? could I buy a battery in germany though my gh4 will be the US model...

kevin_kirchman

@olli66 yes, it is the same battery as the GH3. I don't know about the EU batteries on a US body.

Tron

Looks like Amazon is listing April 30th as the official release date for GH4.

Vitaliy_Kiselev

could I buy a battery in germany though my gh4 will be the US model...

For now batteries do not care where you buy them, but they need to be original ones :-)

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