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4K 8bit 4:2:0 on the Panasonic GH4 converts to 1080p 10bit 4:4:4
  • AlexauwaAlexauwa

    There is an quite old but interesting article by EOSHD about that: http://www.eoshd.com/2014/02/discovery-4k-8bit-420-panasonic-gh4-converts-1080p-10bit-444/

    Did anyone try that? Do color information really improve?

    I am specially interested in the conversion to achieve the 4.4.4. as mentioned here: "Downscaling and transcoding to ProRes or CineForm at 1080p can convert the RGB 4K data from the GH4’s 4K 100Mbit/s codec to the higher bit depth of 10bit and colour sampling of 4:4:4."

    There are various product types such as GoPro Studio (Premium, Professional, etc.) available. Which would I need and how would the workflow be with Premiere Pro CC 2015?

  • 10 Replies sorted by
  • cantsincantsin

    Premiere (and all good NLEs) works in higher bitdepth anyway and upsamples color automatically when you downsize footage. You won't achieve true 10bit 4:4:4 this way though.

  • kankalakankala

    I don't have a GH4, but what I would do is use ffmbc (https://code.google.com/p/ffmbc/wiki/ProResEncoding) in a batch/script file to batch convert all files in a folder.

    something like: ffmbc.exe -i input.mov -pix_fmt yuv444p10 -vf "scale=1920:1080" -vcodec prores -profile hq -pix_fmt yuv444p10 output.mov

    hopefully the order of the parameters does matter, and pix_fmt is done before scale, so you can benefit from the mediated pixels, otherwise there will be no benefit from changing to 444 format

  • maxrmaxr

    Hey guys, case you mised it, here at PV forums @karl already developed a simillar ffmpeg script {4K Downscaling progress topic}... which was later implemented within hybrid... for ANY 4K/UHD footage; actually for any size as long as final output is at least half the size. See grabs, in Hybrid shift + F10 (mac) will open side window for tooltips
    Kostya (slower) is the only encoder mode where can happen. =)
    image AT Misc sub-tab
    image
    Crop/Resize > Main sub-tab = where you select image output sizeimage

  • peternappeternap

    Been meaning to try that Maxr, thanks!

  • maxrmaxr

    @peternap other than becoming a fakir (razor sharp images) one big advantage is that footage stands heavy heavy grade maliciousness :P • Though poor examples, here are a couple videos where I used karl's script...

    NX1 // No added sharpening, grain or noise reduction


    Paul Rean's 4K from hacked F5 // messy resolve early days

  • AlexauwaAlexauwa

    Thanks guys for sharing.

    Are there any gh4 footage experience in 4:2:0? Also in terms of grading after downscaling?

    How do the process work with cineForm?

  • Vitaliy_KiselevVitaliy_Kiselev

    We have big topic on it, try to search.

  • peternappeternap

    @maxr I just installed the latest version. There's a learning curve for us old geezers. I'll play with it tonight. Thanks again.

  • valdi99valdi99

    Tried to downsize my GH4 UHD clip with Hybrid, box "Force 4:4:4 downsize" checked, but I am getting Import-Error:

    [my path here] force444Downsize.avs does not exist!

    And I can't see it in 'Hybrid/avisynthPlugins' subfolder - but should be there, I presume... Any help please..?

  • maxrmaxr

    @valdi99 yup, for some releases now Hybrid's 444 downscale manoeuvre has been broke... but not so Karl's script, mind you ffmpeg seem to have problems with timecode (data stream), so you've got to get rid of it... don't buried too deep though 'cause you might be hungry later :P

     
    4K Downscaling progress topic

     

    ffmpeg -i "INPUT" -filter_complex 'extractplanes=y+u+v[y][u][v]; [u] scale=w=3840:h=2160:flags=print_info+neighbor+bitexact [us]; [v] scale=w=3840:h=2160:flags=print_info+neighbor+bitexact [vs]; [y][us] [vs]mergeplanes=0x001020:yuv444p,format=pix_fmts=yuv444p10le, scale=w=1920:h=1080:flags=print_info+bicubic+full_chroma_inp+full_chroma_int' \ -sws_dither none \ -q 0 -quant_mat hq \ -c:v prores_ks -profile:v 4 \ -c:a copy \ -c:s copy \ -map 0 \ "OUTPUT.mov"
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