Attila Bakos

You're asking the guy who just so happens to have a gay porn actor as his profile picture I know, I know, how do I just so happen to know that... the URL of his picture is telling.

How did you find out that 22%? For a moment let's forget about Lutcalc data. I just shot a grey card at 46% in F-Log, using ISO640 and 1/40s. Then I switched the camera to HLG and shot the same card at ISO1000 and 1/60s. Looking by the numbers it's the same exposure (aperture did not change) but if there's no added gain in HLG then it's practically 2/3 stops lower than F-Log. In this case the grey level is about 32-33IRE.

I tried removing the full range flag, no change. Also tried removing the full range flag & altering all color related tags, no change. Premiere and Resolve seem to completely ignore these tags.

Yes in most cases that LUT will give good results, but I had some shots with pink colors where it was ever so slightly off. Yes you can alter the tags without transcoding, but I don't see why you would do that. Fuji's tags are actually correct, the problem is that the mainstream editors ignore them. If you modify the tags the files will look off even in editors that actually care about the metadata.

@androidlad Upon further inspection I found out that the Rec709toRec601.cube LUT is not 100% accurate, sometimes it will be slightly off. This problem might be something that can't be fixed with a single LUT, or matrix. For a really accurate conversion transcoding seems to be the only way: ffmpeg -i INPUT.MOV -vf colorspace=all=bt709,scale=in_range=full:out_range=full -c:v prores_ks -profile:v 2 -c:a copy OUTPUT.MOV Just remember to switch ProRes to full range once it's imported.

Yeah that's the old way of doing it, but the method androidlad mentioned is faster, I'd recommend that one. The presets are under Effects->Lumetri presets->Technical.

Yes I'm interested in that as well, but unfortunately no external recorder here If you check the HLG files in Assimilate Scratch and in Resolve, they look different. But if you go to the media section in Scratch and change data format from the recognized Rec2020 to Lin/sRGB and change HLG to SDR, they will look the same.

I checked a some footage with the correction matrix, and the funny thing is that I actually prefer the wrong interpretation in many shots

FYI I contacted Blackmagic support about the issue, it has been forwarded to the development team, but that's all they told me.

That's why I believe that assumption is wrong and the data itself is different. EDIT: Forgot to tell you that I experimented with extracting the raw stream and inserting it into another container without any flags. In this case even Scratch shows the difference, so my theory seems to be correct. EDIT2: Or just use this script: ffmpeg -i INPUT.MOV -c copy -bsf:v hevc_metadata=matrix_coefficients=1 OUTPUT.MOV It only changes the matrix coefficients tag to BT.709, and immediately you can see a difference in Scratch. So it's respecting the tags.

I think the underlying YCbCr data is different in the internal version compared to the ProRes version. Both share the same BT.709 primaries but the internal version requires the BT.601 matrix coefficients to convert to the correct RGB values. Resolve and Premiere seems to ignore this flag and they use the BT.709 matrix. This is perfect for the external recording, but not so much for the internal as we have seen. The LUT and the matrix that's included in that package is basicly a multiplication of two matrices, the first one converts from RGB to YCbCr using the 701 matrix, the second one converts YCbCr to RGB with the 601 matrix. So it basicly undoes the wrong YCbCr->RGB conversion and redoes it correctly. Scratch does one thing that Premiere & Resolve does not, it actually gives a shit about the flags

UPDATE: I believe we were looking at this the wrong way. There is only one place for these tags and it's at the stream level, however Premiere and Resolve doesn't even read these flags. Assimilate Scratch does, and if you modify the flags with FFMpeg the footage will look different in Scratch. The difference is also visible with MPC-HC, or FFPlay. At this point I don't think we can do much, maybe tell BM Support that they should care about these flags. This also leads me to believe that the Fuji flags are correct, and the bad interpretation is not a result of a confusion.

I can change the stream metadata tags with the commands I posted earlier. If I list the streams with ffprobe (ffprobe -v error -show_streams INPUT.MOV), then I get this in the original HEVC stream: color_space=smpte170m color_transfer=smpte170m color_primaries=bt709 After converting all to bt709 I get this: color_space=bt709 color_transfer=bt709 color_primaries=bt709 What I don't know is how I can change things on the container level. EDIT: ffprobe -show_format actually shows the container tags, and this is what I get for the original file: [FORMAT] filename=DSCF7556.MOV nb_streams=3 nb_programs=0 format_name=mov,mp4,m4a,3gp,3g2,mj2 format_long_name=QuickTime / MOV start_time=0.000000 duration=25.000000 size=635467264 bit_rate=203349524 probe_score=100 TAG:major_brand=qt TAG:minor_version=0 TAG:compatible_brands=qt TAG:creation_time=2019-01-14T16:13:13.000000Z TAG:original_format=Digital Camera TAG:original_format-eng=Digital Camera TAG:comment=FUJIFILM DIGITAL CAMERA X-T3 TAG:comment-eng=FUJIFILM DIGITAL CAMERA X-T3 [/FORMAT] So there is nothing here about colors. Then it's interesing why changing metadata on the stream level does nothing in Resolve/Premiere.

I see. So it's theoretically possible but we don't have the tools. Doing this by hand is beyond my skills I'm afraid. Btw ffmpeg's manual says, that it modifies headers in the stream: https://ffmpeg.org/ffmpeg-bitstream-filters.html#hevc_005fmetadata

With recent ffmpeg builds you can change HEVC/H.264 flags, and it doesn't solve the issue. There must be something else too. If you want to try it, use this command to change all the color related flags to BT.709: ffmpeg -i INPUT.MOV -c copy -bsf:v hevc_metadata=colour_primaries=1:transfer_characteristics=1:matrix_coefficients=1 OUTPUT.MOV And this to change all to BT.601: ffmpeg -i INPUT.MOV -c copy -bsf:v hevc_metadata=colour_primaries=6:transfer_characteristics=6:matrix_coefficients=6 OUTPUT.MOV