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Unless I'm mistaken, in case of using Dolby Vision on iPhone 12, it's just outputting 1000 nits P3 PQ encoded video, which is when uploaded to Youtube will display Dolby Vision image on a Dolby Vision display only. There is no L1 100 nits Rec-709 tone mapping performed. That means, that image will looks incorrect on rec-709 display. Resolve or for that matter, any color grading software, can output H265 (HVEC) Dolby Vision encoded image, that contains proper L1 metadata for proper payback on both Dolby Vision and rec-709 displays.
Jake,
I didn't really know either what was actually involved in the iPhone's Dolby Vision workflow, what was done in the phone and what needed to be processed later in another program. I think I probably need to spend a little more time trying to understand the proper workflow of Dolby Vision for this Phone.
As far as I understand, the ONLY thing iPhone does is PQ gamma encoding for Dolby Vision playback, nothing else. There is no L1 tone mapping produced, as far as I can tell.
So, if that is indeed the case, that is why you'd need to use Resolve to produce a PROPER Dolby Vision HVEC encoded videos for the upload, if you want everyone to be able to see correct images regardless of the display.
Correction:
I was just reminded, that iPhone records HDR using HLG tone curve. And then, I'm guessing, it does the PQ encoding for Dolby Vision playback. Still, no tone mapping for Rec-709 though. I wonder, if using HLG recording was done because HLG widely used for live over the air HDR broadcating. It is very easy to create two streams of HDR and SDR using HLG. I wonder, if Apple planning to use HLG recording for SDR conversion on the fly?
Last edited by Jon Dishler; 11-07-2020 at 10:35 PM.
Yeah, I read that for the package media market HDR content, HDR based on the PQ tone curve is still the preferred method. But like you said, HLG is the preferred method for live streams. HLG , from what I understand, can carry both the HDR and SDR signal in the same stream. If your TV is capable of HLG playback, it will display the image that way. If your TV is not capable of HLG HDR playback, it will showcase a SDR slightly enhanced image.
Except HLG is not what is uploaded, it's what's recorded, like any camera would, say Sony records S-Log3 or Arri AWG Log-C or Red IPP2 with LOG310. What's uploaded is standard Dolby Vision HVEC PQ/1000 nits P3/D65, not HLG. And properly encoded H265/HVEC can also carry HDR image with XML Dolby Vision tone mapping information, when used with compliant software like QT or VLC, it can utilize this information on the fly for proper SDR displaying if needed.
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