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Mac app to resample GH4 8 bit 4:2:0 to 10 bit 4:4:4


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#1 Thomas Worth

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Posted 09 April 2014 - 12:52 AM

Hey guys, I've written a really simple command line app for Mac that will resample GH4 footage from 4K 4:2:0 to 2K 4:4:4 using pixel summing. This will give you real 10 bit data in the luminance channel, so it's not just doing a brute-force bump from 8 bits to 10 bits. There actually is some interesting pixel finagling going on here:

 

http://www.mediafire...hrn9f/gh444.dmg

 

There's no GUI, so you'll need to run it from the terminal. Do this by copying the app into the directory that contains the GH4 MOV files and using the following command in a terminal:

./gh444 INPUTFILE.MOV

Make sure you cd to the current directory first if necessary. You can do this by typing "cd" into the terminal, add a space, and then drag the folder containing the MOV files into the terminal window. It will automatically add the path to the cd command. It'll look like this:

cd /path/to/gh4/files

The app will spit numbered DPX frames out in a folder named "dpx_out."

 

I'd love for you guys to give it a try and see if you find it useful!


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#2 jonpais

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Posted 09 April 2014 - 03:19 PM

Sounds great. I'm sure I'll have questions for you once I actually have the camera in my hands. Any idea about the processing power required to handle 10 bit 4:4:4? Same as 4K?

#3 Thomas Worth

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Posted 09 April 2014 - 07:27 PM

Sounds great. I'm sure I'll have questions for you once I actually have the camera in my hands. Any idea about the processing power required to handle 10 bit 4:4:4? Same as 4K?

 

It's typically easier for the CPU to process uncompressed data, but disk bandwidth is more of an issue. Since this app is designed mainly for testing, the DPX files will be large and require lots of storage bandwidth. If it makes sense, I can add the ability to save ProRes 4444 files at 2K. Generally speaking, ProRes footage is much easier to decompress and display than H.264 footage, even when it's 444/RGB. I haven't run into any problems with GH4 footage, though. The files are relatively small and any recent system should have enough CPU power to play them back in realtime.



#4 Richard Wait

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Posted 09 April 2014 - 07:49 PM

Not to look a gift horse in the mouth! Any thoughts on a GUI? 

 

How do you program something like this anyway! (I'm really impressed!) and what are DPX files?



#5 Julian

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Posted 09 April 2014 - 08:40 PM

Windows version? ;) I'd give that a try for sure. Getting my hands on a GH4 v 1.0 in a few days...



#6 EOSHD

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Posted 09 April 2014 - 10:14 PM

Great news. How are you finding the 2k images Thomas? Does it smooth the slight aliasing on the car windows in the Porsche shot?



#7 Thomas Worth

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Posted 09 April 2014 - 11:18 PM

Here's a 16 bit PNG file, converted from a DPX file output by gh444:

 

http://www.mediafire...ywaq/gh4_2k.png


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#8 Sean Cunningham

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Posted 09 April 2014 - 11:40 PM

Forgive the re-post from Andrew's other thread on the subject but I wonder how hard would it be to, instead of summing, do a poisson disc sample to arrive at the 2K image?  



#9 EOSHD

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Posted 10 April 2014 - 12:13 AM

Here's a 16 bit PNG file, converted from a DPX file output by gh444:

 

http://www.mediafire...ywaq/gh4_2k.png

 

Impressive.



#10 KarimNassar

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Posted 10 April 2014 - 08:42 AM

very interesting thank you.

 

Can you share just 1 frame of the original 4k and the same frame downsample to 2k 10bit?

 

Just to experiment in post to test the difference 


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#11 thementalist

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Posted 10 April 2014 - 09:16 AM

+1 for windows version

It's not about gh4, it's how we say fuck to firmware limits on panasonic, canon, Nikon, etc

#12 JLemos

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Posted 10 April 2014 - 11:58 AM

What could be the resulting file converted to 2.5K?

I think that in terms of size it could be of general interest, or at least of my general interest.  :)



#13 Jack Danini

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Posted 10 April 2014 - 02:45 PM

+1 for Windows Please! :) Thanks



#14 etidona

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Posted 10 April 2014 - 03:39 PM

Too much numbers for my tastes: someone could please verify if the downscaled version grades better than the original?


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#15 Ebrahim Saadawi

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Posted 10 April 2014 - 03:49 PM

Please show us examples. Proof. That is awesome and well done Thomas if true
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#16 James_H

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Posted 10 April 2014 - 05:38 PM

Here's a GUI I quickly put together:

 

http://www.mediafire...l/GH444_GUI.dmg

 

You still need to download the original gh444 file.  Let me know if it's broken.  It's super basic.  It doesn't provide any info on progress, but it'll let you know when it's done.

 

Edit:

A little explanation:

  • Download the file, mount it and copy "GH444 GUI" to your computer somewhere (e.g. Applications).
  • Open the app, click "Browse" to specify which file you want to convert.  The output will be in a folder called dpx_output in the same folder as the 4K file.
  • Click "Start"
  • Select the gh444 file that Thomas Worth provided
  • Wait.  A popup with the word "Done" will been shown when it's done.

Known issues:

  • It doesn't show progress.
  • If you cancel it, it will still say "Done"
  • Not sure if it works with OS X 10.7 or earlier, I haven't tested.
  • No way to set the output directory

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#17 EOSHD

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Posted 10 April 2014 - 05:39 PM

Here's a GUI I quickly put together:

 

http://www.mediafire...l/GH444_GUI.dmg

 

You still need to download the original gh444 file.  Let me know if it's broken.  It's super basic.  It doesn't provide any info on progress, but it'll let you know when it's done.

 

Great stuff!! Thanks a million James.


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#18 Julian

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Posted 10 April 2014 - 09:13 PM

Here's a 16 bit PNG file, converted from a DPX file output by gh444:

 

http://www.mediafire...ywaq/gh4_2k.png

 

Can someone (Andrew?) grab the exact same frame from the 4K source file and post it as a 16 bit PNG file?



#19 morsafr

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Posted 13 April 2014 - 04:51 PM

Hi all,

 

I experimented with this piece of software but I get inconsistent results with some bad frames.

 

I tried both with and without the GUI.

 

My setup : Mac Pro 2013 with Mavericks, using Resolve 10.1.4 for grading the DPX files.

 

Thanks for your feedback.



#20 dash__dot

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Posted 13 April 2014 - 11:40 PM

I can post some 10 bit and 8bit 4k files that can be downsampled and the grade compared if it would help the discussion about how much it helps? I am on PC so I can't do the comparison myself unfortunately.






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