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[bogdanbz]

I have "Convert HLG HDR to HDR10 for pass through" in JRVR settings.

However, when I play this file fragment which is supposed to be a HLG stream, JRVR plays it back as SDR: download link.

MediaInfo says this about it:

Code: [Select]

Color primaries                          : BT.2020
Transfer characteristics                 : BT.2020 (10-bit)
transfer_characteristics_Original        : HLG / BT.2020 (10-bit)
Matrix coefficients                      : BT.2020 non-constant


[jmone]

Edit: as I was typing Hendrik replied......   The file does not play for me either as HLG but others do.

I checked MC's playback of your file with a known HLG (the one of the right).  I see yours is identified by JRVR as 2020 but with a BT.1886 transfer not HLG - note: BT.1886 is a std the BBC uses, and it is similar (but not the same) as Rec709 + 2.4 gamma.  So I chucked it into Davinci Resolve and it was not automatically identified as HLG (or anything).  So basically, I'm not much help in working out what this clip really is and if it is MediaInfo or JRVR that is miss identifying it..... but I'm sure Hendrik will.

[Hendrik]

I see what the problem is. The information in that file is contradicting itself. The container says SDR, and the video says HLG. And the container wins, typically.

[jmone]

FWIW, I used MKVToolNix GUI to change "Transfer Characteristics" from "14" to "18" and the file now plays correctly.

[bogdanbz]

Thank you for figuring this out.

I did not realize MediaInfo does not show container settings. And I had no idea what the numerical values for Transfer characteristics mean.

[jmone]

MediaInfo does seem to report it.  That change from 14 to 18 changed:
Transfer characteristics from BT.2020 to HLG

...but I've no idea if the other tags are correct, or even if this is the right way of tagging such files.  I did not find any doco (did not look too hard) about what the corresponding values do in MKVToolNix GUI just a post of someone else with HLG MKV issues and this was their "fix". 

[Hendrik]

Media Info is a bit imprecise. I would really prefer if it showed the source of information rather then just throwing it all together into one dump.

[bogdanbz]

Ah I see, the "Original" was referring to the video stream, and the other line was referring to the final value, considering the container.

Code: [Select]

Color primaries                          : BT.2020
Transfer characteristics                 : BT.2020 (10-bit)
transfer_characteristics_Original        : HLG / BT.2020 (10-bit)
Matrix coefficients                      : BT.2020 non-constant
vs

Code: [Select]

Color primaries                          : BT.2020
Transfer characteristics                 : HLG
transfer_characteristics_Original        : HLG / BT.2020 (10-bit)
Matrix coefficients                      : BT.2020 non-constant

The value for "Transfer characteristics" was "BT.2020 (10-bit)", instead of "BT.1886" that JRVR used, so I didn't realize that's where the problem was.

[jmone]

Maybe, but my other HLG test clip does not have a transfer_characteristics_Original at all (but it is an MP4) so that line may not even be required.  Also, I noticed over at github Hendrik has committed the following change

Preserve HLG when a frame indicates it, instead of overriding it with…

… container data

Containers might indicate the corresponding SDR mode, but HLG is going
to be more precise here.

Anyway, looks like you're good to go for playback in MC.

[bogdanbz]

It might be that "transfer_characteristics_Original" is only displayed in Media Info when the video stream has a different "transfer characteristics" than the "transfer characteristics" set on the container.

I remuxed the files yesterday and now everything plays properly.