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Best method for converting true 4K 4096x2160 Broadcast quality HDR to SDR - Any tips?

Forum|Forum|2 years ago
August 29, 2023
3 replies
1579 views

Does anyone have a tip for converting true 4K 4096x2160 broadcast-quality HDR to broadcast-quality SDR?

There could be a number of episodes, so if possible, I'd like to avoid too much tinkering, and apply the same process to all versions.

Any help is greatly appreciated.

PS. I'm working on a Mac, OS Monterey.

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R Neil Haugen

Legend

Working within the constraints of Premiere for broadcast HDR is an intriguing thing. Perhaps @dhelmly might be able to give some expert advice here? I'd sure appreciate it if he or @Karl Soule' could add advice here. Or @Jarle Leirpoll .

Knowing precisely what the broadcasters you work with require would be necessary, of course, for a definitive answer. Past that, it's only a theoretical discussion. Which can be interesting but not necessarily applicable to any one user's ... or broadcaster's ... needs. So here goes the theoretical discussion ... again, as I understand things at this time.

Premiere is built around working in HDR with either HLG or PQ formats. HLG is more to get a direct-export process, as I understand it. Where PQ is probably more suited for passing on to another worker in video post. Can I put enough qualifiers on this paragraph? lol

Getting one 'grade' that works both for HDR and SDR deliverables is kinda the Holy Grail of the colorists at this time, but ... unless your standards are pretty low, there tends to need to be an SDR trim pass. For upper level work, at least ... but then, that's probably going to be through Resolve or Baselight with a Dolby-Vision license involved. Premiere isn't capable of working in DV HDR at this time.

The normal "best practice" ... or at least, most commonly used, and most suggested ... is to do the HDR grade as the master, then do trims from that for SDR deliverables. However, I think only D-V is setup to handle two data sets in the same deliverable package.

So for HLG workflows, as I understand it ... an HLG file will be typically the only deliverable, and it relies on TVs being able to down-drop that to SDR within the TV hardware/firmware. I was following a colorist's discussion on delivering HLG, and one said his shop had tested an HLG file across several computer systems and several TVs of various eras. And wow ... was that a different image depending on the hardware involved!

Getting back to your needs, does the broadcaster utilize HLG, and is that their deliverable spec? Do they specify instead say HDR10 or HDR10+?

And if they do specify HLG, do they also take a second deliverable in SDR/Rec.709?

Everyone's mileage always varies ...

AlexxxxPAuthor

Participating Frequently

Hi, thank you once again for your reply.

I'm working for a relatively small company that distributes content worldwide. In most cases, we ask producers to deliver to either US or European standards (frame rates, timecodes, etc.), the audio spec is a bit more specific.

We then deliver to a broadcaster's requirements wherever they are in the world. For this reason, I don't have a nailed-down delivery spec as such. Apologies that it's so vague.

The producer asked if he could deliver his masters in HDR, so I'm trying to work out whether accepting these files is going to land me with a huge amount of work to do as most broadcasters are still requesting SDR.

I guess the best way to find out is to accept. Thank you for all your help. A

PS. And thanks again to Karl too. @Karl Soule'

R Neil Haugen

Legend

I work for/with/teach pro colorists. Most of whom, naturally, are based in Resolve, the ones that aren't are in Baselight. I use Resolve anytime I'm in the office with my full setup as I test between the BlackMagic and Adobe spheres.

The guys I've work closest with were the ones that Dolby Labs hired to do the in-house Dolby produced DolbyVision training videos. And among the earliest adopters for broadcast/streaming use of DV.

They consider HDR to be the Wild Wild West of video post/production, and most certainly, delivery. A lot of broadcasters technical staffs aren't even knowledgeable on the exact specs they should be asking for, so spec sheets are not uncommonly either too vague, or have one or more things that are actually ... not optimal.

And things are always changing still. I do recommend reading up on any HDR stuff on the long list of whitepapers at lightillusion.com and there's a TON of stuff on using calibrated montors & such there ... but check out their HDR information.

And ... note I 'work' there, but some of the best stuff on pro use of HDR for actual delivery is at MixingLight.com ... which is a paid membership site. They do have some things (including a couple of mine) outside their paywall however.

And Warren Eagles and Kevin Shaw's Interational Colorist Academy is another place with excellent help on HDR.

For YouTube, Cullen Kelly and Daren Mostyn are the two I'd actually mention first.

Neil

Everyone's mileage always varies ...

R Neil Haugen

Legend

The clip, sequence (working), and export color spaces need to match. Unfortunately, there isn't one specific fix for all cases.

And if you're talking ready to deliver, that always requires user attention.

As some clips, shot in a number of manufacturer log 'spaces', can be tonemapped, if they are a log image and Premiere "recognizes" and can work with. Most Sony do ok, but there's a Canon and Panny log that either aren't recognized or can be spotty.

And RAW footage needs to have the user set some controls no matter whether you're working HDR or SDR.

So ... it's all doable, just takes some knowledge of the tools and needs.

Give me more details of the media involved, I can give specific steps for each.

Everyone's mileage always varies ...

AlexxxxPAuthor

Participating Frequently

Hi R Neil, Thank you very much for your reply.

Just to be clear, I'm expecting a completed master/s in HDR, not the raw footage.

So, I'm just wondering if there's a way to take a finished master into Premiere (or Encoder) and make an adjustment (or set of adjustments) across the entire master that I could export as an SDR master.

I don't think it has to be 100% perfect, but if I get it to 98-99% looking OK, and within 'legal' limits for Broadcasters, then that would probably be acceptable.

Working with HDR is new to me, so if you think what I'm asking for isn't really workable, and the master/s needs to be specifically re-graded shot to shot for SDR, then I'll just have to ask the producers to arrange it as I've too much on.

It's late here in the Netherlands, so heading to bed. Thank you once again. A