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  1. Member
    Join Date
    Aug 2019
    Location
    Australia, NSW
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    I'm trying to build a python application to convert a 10bit DPX sequence to a 4k DNXHR_444 MOV with a Arri to Rec709 lut, just as I would in Davcincci resolve.

    Code:
    ffmpeg -f image2 -framerate 24 -pattern_type glob -i INPUT.dpx -c:v dnxhd -profile:v dnxhr_444 -vf lut3d=ArriAlexa_LogCtoRec709_Resolve.cube,colormatrix=bt601:bt709 -pix_fmt yuv444p10le -c:a pcm_s16le -y -timecode 00:00:41:16 OUTPUT.mov
    When comparing the output to the dpx in resolve with the lut on it, there is a slight colour shift making everything slightly more red. Even when i take the lut out of the ffmpeg code, there is still a slight redness. The colourmatrix helps a bit to get it closer but it isn't close enough. Any ideas why I can't get them to match?

    Here is a:
    - JPG - reference of what the DPX + LUT should look like
    - DPX - a frame of the dpx sequence I'm trying to convert to DNXHR_444
    - the ArriLogC_to_Rec709 LUT to be applied to the DPX
    Let me know if you need anything else.

    https://drive.google.com/drive/folders/1j2Qq1sV5ZJJsMYe3DOFOV0dnQ3VIotcw?usp=sharing
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  2. The problem is the RGB => YUV conversion. And colormatrix is to be avoided if possible (8bit, quality issues)

    In ffmpeg, zscale is the preferred method these days

    This works ok, confirmed in Resolve 15, and other programs
    eg.
    Code:
    ffmpeg -i DPX(what_I_want_to_convert_to_DNXHR).dpx -vf lut3d=ArriAlexa_LogCtoRec709_Resolve.cube,zscale=matrix=709,format=yuv444p10le -c:v dnxhd -profile:v dnxhr_444 -an test_zscale.mov
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