I've added option which will add the additional SEI for HLG in NVEnc 5.19 as --atc-sei, please have a try.

Thanks Rigaya

I just tested new option. It should be working but there is one thing. MediaInfo is now reporting two rows of information instead of one for "transfer" when I use --atc-sei arib-std-b67

Transfer characteristics : HLG
transfer_characteristics_Original : HLG / HLG

I don't know if it's of any help but here is the log of ffmpeg's trace_headers option

Original

NVenc

I don’t seem to have trouble myself, there is only single "Transfer characteristics" line in MediaInfo. Also I don't think the header of the NVenc output is invalid. Would you share the full command line you have used to check?

x64\NVEncC64.exe -i "4K_HLG_Sample.MP4" -o F:\temp\test.mp4 -c hevc --output-depth 10 --transfer arib-std-b67 --colormatrix bt2020nc --colorprim bt2020 --atc-sei arib-std-b67

That's weird, maybe it's a bug in NVencC matroska muxer but this only happens when NVencC's output is mkv. MediaInfo output is same as yours when I remux NVEnc mkv to mp4 or when the output is raw h265.

Anyway this can be considered as solved :)
Thanks again for your work on this great software.

Thanks, I also got two "Transfer characteristics" line when I wrote in mkv format.

Checking the mkv video header with mkvtoolnix, it seems like the first line is coming from mkv header as it only has the VUI part for transfer characteristics.

Transfer characteristics : HLG < from mkv header
transfer_characteristics_Original : HLG / HLG < from HEVC stream

I'll try if I can avoid this.

I've changed mux behavior in NVEnc 5.20, to avoid two lines showing up for Transfer characteristics in MediaInfo when writing to mkv format.