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

[Christof Wolf]

 

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.com/download/f7h950spj5hrn9f/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!

 

Thomas,

 

thanks for your app! I tried a 4K 25p file - it works, but it only gives me a dpx-sequence with 24fps as an output. Is there any option I can add at the command line that would give me a dpx with 25fps?

 

thanks

christof

[John Gary Whalen Jr]

I am getting very, very frustrated. I am following the instructions to the letter and I keep getting “no such file or directoryâ€.

 

 

Someone please help. First I copied the gh444 app into the same folder as my GH4 clips. Then…..

 

1. Opened Terminal

2. Typed “cd"

3. drag and dropped the folder containing my GH4 clips

4. Then entered "./gh444 INPUTFILE.MOV†sot it looks like this:

 

 

cd /Users/TaJnB/Movies/untitled folder./gh444 INPUTFILE.MOV

 

I’ve tried only opening terminal and typing "./gh444 INPUTFILE.MOV†“ and still nothing. Please help.

[tupp]

Change the name of folder "/Users/TaJnB/Movies/untitled folder" to a name without any spaces (or special characters), such as: /Users/TaJnB/Movies/gh4files

 

Make sure that the gh444 app and your gh4 mov files are in the directory /Users/TaJnB/Movies/gh4files

 

Type at the terminal prompt:

cd /Users/TaJnB/Movies/gh4files

Press "enter" (or "return).

 

The working directory of your terminal should now be "/Users/TaJnB/Movies/gh4files"

 

Now, type at the terminal prompt:

./gh444 your_gh4_mov_file

Replace "your_gh4_mov_file" with the actual name of your first gh4 mov file (it seems that you have to do each file one at a time).

 

Press "enter"  (or "return").

 

The gh444 app should now be converting your first gh4 mov file.

[dhessel]

While this may be a useful exercise for you on learning how to run commands through the terminal on a mac, highly recommended by the way, however the whole down scale to 10bit theory is interesting but fundamentally flawed. Simply put it doesn't work and there is really nothing to gain by using this app over just simply bringing your 4K content into a 1080P timeline and down scaling to fit. I believe it will still be 4:4:4 even when done in a NLE, made no attempts to verify that however. Years of research have gone into to scaling algorithms to get the best possible results and I suspect if anything this app would result in a lower quality downscale if anything.

 

Has anyone actually compared the output of this app to down scaling in a NLE to see if there is any improvement at all?

[tupp]

While this may be a useful exercise for you on learning how to run commands through the terminal on a mac, highly recommended by the way, however the whole down scale to 10bit theory is interesting but fundamentally flawed. Simply put it doesn't work...

Actually, it does work and people have been doing it for years.

You CAN sacrifice resolution for increased bit depth, with certain caveats:
- banding in the original image won't automatically disappear with the increased bit depth;
- the color depth can never be increased (bit depth is not color depth).

This process was discussed extensively in >this thread.

[hmcindie]

Sure but you don't need special software for it, any modern-ish NLE will basically do a good scale.

[johnnymossville]

Is this app still available for download?  

[dhessel]

Actually, it does work and people have been doing it for years.

You CAN sacrifice resolution for increased bit depth, with certain caveats:
- banding in the original image won't automatically disappear with the increased bit depth;
- the color depth can never be increased (bit depth is not color depth).

This process was discussed extensively in >this thread.

 

Maybe I should clarify. Yes it is possible to downscale to 10bit 4:4:4. This app and that thread are all about the theory that you could use this down scale as an alternative to recording 10bit native and then use that extra depth during color grading. That theory is flawed and doesn't work since the down scaled 10bit is no more accurate in terms of the recorded color information than it's 8bit source and that it is not the same as recording 10bit during capture. Sure there are benefits in super sampling the image during downscale but you don't need a special app for that.

[Inazuma]

Anyone have examples of the real work benefits of doing this?

[tupp]

The primary benefit of this practice is that the full color depth can be retained when converting to a lower resolution.  Otherwise, color information is being discarded.

[sunyata]

oh no, not this thread.. 

 

you can just scale in your NLE of choice (stated above), or ffmpeg can do this and more for free.

 

for example, i wrote this expression for my batch conversions to dpx sequences, which uses bash, sed, and ffmpeg (you only need to install ffmpeg). it takes a folder of clips (mov extension), converts them all to 10bit 4:2:2 dpx, and saves the sequences into folders with the clip's filenames, minus their extensions. this command will work on mac and linux using the bash shell, which i think is still default in osx.

 

"for i in `ls *.mov`; do mkdir `echo $i | sed 's/(.*)..*/1/'`; ffmpeg -r 23.98 -i $i -s 1920x1080 -pix_fmt gbrp10le `echo $i | sed 's/(.*)..*/1/'`/$i".%04d.dpx"; done"

 

if you're on a mac and don't have ffmpeg installed, google how to install it for mac, tons of walk-through's out there. 

 

also, this is just an anti-alias thing, you're not getting true HD (as in same as if recorded at) 10bit 4:2:2 w/o banding etc from a 4k 8bit 4:2:0 file.. if you see chromatic compression in your shadows, or banding, it's still going to be there, just a little smaller and mushier from the resample.

[Isaac Lee Watson]

Hello,

 

The download link for this file no longer works. Is there an updated link?

 

Thank you for your time.

[yohanesbintang]

yes, the download link for this file no longer works, thanks in advance to correct the link....

[Isaac Lee Watson]

Any word on this? No answers? Is there anyone out there that has downloaded this that might be willing to re-upload it? Thanks.

[dhessel]

The reason why there are no responses and the links are down is that the whole concept of 10bit from down scaling to HD is flawed, it doesn't work the way it was originally theorized that it would. This app won't give you anything more than just scaling down in your NLE. The NLE is probably better since it has more advanced scaling algorithms anyway. I don't have it so I can't upload it but there is nothing to gain by using it anyway. 

 

Check out the previous posts in here if you want to know why.

[Isaac Lee Watson]

Ok, thanks for the reply and explanation... I had read through the responses before, but there seemed to be differing opinions on it, and I'm a "hands-on-test-things-myself" kind of person (I'm from Missouri...the "Show Me" state), so I figured I'd get my hands on it.

 

I appreciate the answer!

[dhessel]

I can understand that completely. I am the same way, and I fact I did test it myself as well in a script I wrote on Windows. If I had the app I would post it but I am on Windows so never downloaded it.

[JohnLendvedVideography]

Is anyone else getting this message when they try to download the app? Why isn't it working for me?

 

  Invalid or Deleted File.

The key you provided for file access was invalid. This is usually caused because the file is no longer stored on MediaFire. This occurs when the file is removed by the originating user or MediaFire.

Still have questions, or think we've made a mistake? Please contact support for further assistance.

[ilariobiraghi]

Hi, the mediafire link is invalid, where could I download the software, please? Thanks a lot.

[BenEricson]

Would this method also work on the Canon XC10?