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Author Topic: HLG Support? Any thoughts?  (Read 1020 times)

jmone

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HLG Support? Any thoughts?
« on: May 09, 2021, 02:37:33 am »

I'm getting more and more original HLG material from my Camcorder (and now a drone).  I know that madshi has been very quiet about HLG support for madVR so I'm at a point where I'm trying to work out what to do before my backlog of material to edit gets too big!  Currently I'm rendering out my HLG footage as HDR10 and then a SDR709 version as well..... but,

- I'd prefer to shoot, edit, and playback in HLG.... yet I'm not sure if there is any (Windows) Video Renderer that both supports HLG and can be loaded by MC.  One advantage of for HLG is it will look "OK" on both a SDR and HDR device so I'd just have one file.

Thanks
Nathan



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tij

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Re: HLG Support? Any thoughts?
« Reply #1 on: May 19, 2021, 10:09:19 am »

Out of curiousity ... what container those file use ... and what encoding?

Also ... can TV play those fikes in HLG?
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jmone

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Re: HLG Support? Any thoughts?
« Reply #2 on: May 22, 2021, 05:42:35 am »

As it's a Gamma Curve (709 for the first part then Log for the extended area) I guess pretty well any Container, Codec, and Transmission (both ATSC and DVB supports it) will work just fine.... but, you just need a renderer in the SW or HW (eg TV) to be able to recognise the meta data else it will just display as SDR.  The "good" thing with HLG is it looks pretty much like std 709 SDR material on non HDR sets, and looks like HDR on HLG HDR sets.  This is why BBC and NTT have really been pushing it as it only need the consumer equipment to be HLG aware to display it and is backward compatible with non HLG displays.  Sounds good!  One grade for both SDR and HDR!  Unfortunately..... I'm going to "give up" on HLG and shoot Log then grade for HDR10 instead as:
- there is no Tone Mapping or passthrough? in madVR for HLG
- not all my displays support HLG though they do HDR10
- My DJI Air Air 2S HLG recordings are terrible noisy (as really really bad noise in shadows)

The downside, is I may have to also then make a SDR grade if I want to share such content with others (eg family), and all this "grading" takes time I'd rather not spend.
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tij

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Re: HLG Support? Any thoughts?
« Reply #3 on: May 22, 2021, 06:08:56 am »

HDR10+  seems like in the same boat ... nothing support it

I had chat with one guy ... and he was able to trigger HDR10+ by setting TV that support it as DLNA renderer (of course he needed eARC to get HD sound out of it, which he did not have and it was a deal breaker for him).

Curious though ... if HLG can be played in SDR on stuff that does not support it ... why you need to regrade it to SDR?
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Hendrik

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Re: HLG Support? Any thoughts?
« Reply #4 on: May 22, 2021, 07:44:39 am »

Curious though ... if HLG can be played in SDR on stuff that does not support it ... why you need to regrade it to SDR?

Thats more of a theoretical feature, it doesn't look quite right to play it as pure SDR.
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jmone

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Re: HLG Support? Any thoughts?
« Reply #5 on: May 22, 2021, 05:37:04 pm »

https://en.wikipedia.org/wiki/Hybrid_Log-Gamma#:~:text=Hybrid%20Log%2DGamma%20(HLG),dynamic%20range%20(SDR)%20region.
https://www.xdcam-user.com/2017/07/what-is-hlg-and-what-is-it-supposed-to-be-used-for/

The idea is you don't have to have two grades with HLG, it will look "SDR" ish on SDR TV's and "HDR" ish on HDR TV's but as Hendrik points out it is a compromise (so you could get a "better" dedicated image with a pure SDR and HDR grade).  The other concept with HLG is like cameras that capture SDR video, it is designed as a straight to consumption HDR format that does not (and should not) require grading.... aka straight to broadcast, as the camera has already applied a grade.  HLG would have been "good enough" for me with what I was shooting, but the lack of HLG Rendering Support and the issue with the Air 2S being super noisy when recording in HLG mode makes it a poor choice for me currently.  So that leaves me shooting in LOG which then must be graded for a particular output (such as Rec.709 (SDR), 2020/ST2084 (HDR10), Dolby Vision, or even 2020/HLG) and unless I output to HLG, I'd need both a HDR10 and Rec709 SDR grade depending on the display equipment that will be used. 
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