I have been investigating about the Dolby Vision feature of the iPhone 12 series as well as why we are unable to AirPlay these in DV format.
As some of you might already know, we are currently unable to AirPlay these videos in Dolby Vision to ATV4K as they all play as SDR (Setting ATV4 always in Dolby Vision and playing these is not the same thing and it is wrong IMO). Also, "Photos" on ATV4 does not trigger Dolby Vision when playing these videos that are recorded on iPhone 12 with HDR on.
While investigating, the best I could come up with how to play these videos recorded on iPhone 12 pro was to save them on an USB drive (or through NAS) and finally I was able to play them in "HLG HDR" format on my TV (LG OLED C7P - 2017 Series) via native video player. However, I still could not quite understand why I was getting "HLG HDR" format instead of Dolby Vision on my TV until I found some interesting interview with Jon McCormack - VP software at Apple and it started to make some sense to me finally.
Here's the important part;
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– I watch the current iPhone ‘dolby horizon HDR’ video, and when it comes to the computer it’s HLG curve. This is not quite the same as the dolby Horizon material we used in the past, which USES PQ curves that record absolute brightness values. Why do you do that?
inside the iPhone, this is a complete ‘dolby horizon’ shooting process. This is a new 8.4 standard. We have worked closely with Dolby to make this standard more widely available and more devices will benefit from it.
you see the HLG curve for better compatibility. We wanted this exported video file to be able to be viewed on a variety of devices and screens, and the HLG curve met that requirement.
– when I watch HDR videos now, if they go straight from the phone to the social network, the color is a little off. How to solve this compatibility problem?
In the internal video flow of iPhone, we saved two sets of metadata, one corresponding to HDR and one corresponding to SDR.
with the launch of iPhone 12 and 12 Pro, we will be pushing a new version of iOS, and there will be a new API that will let apps tell the system if they support dolby horizon HDR video, so that the system can upload the correct version of dynamic range.
– thank you.
interviewer note:
in our tests, we saw videos in HDR format ‘Dolby Vision, Version 1.0, dvhe.08.04, BL+RPU, HLG compatible’.
in the ‘dvhe.08.04’ string, ‘dvhe’ refers to Dolby Vision High Efficiency. According to the white paper Dolby Vision Profiles and Levels Version 1.3.2, ’08’ means profile Version 8 and ’04’ means level 1920 x 1080@30.
Profile 8 is coded as’ 10-bit HEVC ‘, signal compatibility as’ 1, 2, or 4 ‘, namely HDR10, SDR and a standard for ‘working on specific broadcast and mobile devices’ and’ optimized for specific devices’. (This is from a public profile dolby released on September 16, 2019.)
‘BL+RPU’ refers to ‘base layer + reference picture unit’. We suspect that the HDR video captured by the iPhone may be outside the HLG curve, providing the playback device with the RPU to correctly interpret SDR and HDR colors, re-interpreting the colors recorded by the HLG curve — both what Jon McCormack calls’ two sets of metadata ‘.
there are actually three sets of metadata in the videos that the iPhone 12 records. We don’t know yet what their respective USES are.
as of press time, no more information about ‘Dolby Vision Profile 8.4’ and ‘new Dolby Vision API’ on iOS, macOS, and tvOS could be found.
----------------------------------------------------
Link to the original webpage. Also, here's the Dolby Vision profiles document directly from Dolby.
My conclusion is that the TV I have (LG C7P 2017 series) does not support the new DV profile - dvhe.08.04 so it falls back to HLG and I am unable to see the full curve with this TV. New TV's with the proper support, we should see in better curve.
However, this still does not answer why ATV4k won't AirPlay these videos at least in HLG format. My guess is that ATV4K does not support HGL HDR currently. Maybe on future updates. I think I am done investigating this..
As some of you might already know, we are currently unable to AirPlay these videos in Dolby Vision to ATV4K as they all play as SDR (Setting ATV4 always in Dolby Vision and playing these is not the same thing and it is wrong IMO). Also, "Photos" on ATV4 does not trigger Dolby Vision when playing these videos that are recorded on iPhone 12 with HDR on.
While investigating, the best I could come up with how to play these videos recorded on iPhone 12 pro was to save them on an USB drive (or through NAS) and finally I was able to play them in "HLG HDR" format on my TV (LG OLED C7P - 2017 Series) via native video player. However, I still could not quite understand why I was getting "HLG HDR" format instead of Dolby Vision on my TV until I found some interesting interview with Jon McCormack - VP software at Apple and it started to make some sense to me finally.
Here's the important part;
----------------------------------------------------
– I watch the current iPhone ‘dolby horizon HDR’ video, and when it comes to the computer it’s HLG curve. This is not quite the same as the dolby Horizon material we used in the past, which USES PQ curves that record absolute brightness values. Why do you do that?
inside the iPhone, this is a complete ‘dolby horizon’ shooting process. This is a new 8.4 standard. We have worked closely with Dolby to make this standard more widely available and more devices will benefit from it.
you see the HLG curve for better compatibility. We wanted this exported video file to be able to be viewed on a variety of devices and screens, and the HLG curve met that requirement.
– when I watch HDR videos now, if they go straight from the phone to the social network, the color is a little off. How to solve this compatibility problem?
In the internal video flow of iPhone, we saved two sets of metadata, one corresponding to HDR and one corresponding to SDR.
with the launch of iPhone 12 and 12 Pro, we will be pushing a new version of iOS, and there will be a new API that will let apps tell the system if they support dolby horizon HDR video, so that the system can upload the correct version of dynamic range.
– thank you.
interviewer note:
in our tests, we saw videos in HDR format ‘Dolby Vision, Version 1.0, dvhe.08.04, BL+RPU, HLG compatible’.
in the ‘dvhe.08.04’ string, ‘dvhe’ refers to Dolby Vision High Efficiency. According to the white paper Dolby Vision Profiles and Levels Version 1.3.2, ’08’ means profile Version 8 and ’04’ means level 1920 x 1080@30.
Profile 8 is coded as’ 10-bit HEVC ‘, signal compatibility as’ 1, 2, or 4 ‘, namely HDR10, SDR and a standard for ‘working on specific broadcast and mobile devices’ and’ optimized for specific devices’. (This is from a public profile dolby released on September 16, 2019.)
‘BL+RPU’ refers to ‘base layer + reference picture unit’. We suspect that the HDR video captured by the iPhone may be outside the HLG curve, providing the playback device with the RPU to correctly interpret SDR and HDR colors, re-interpreting the colors recorded by the HLG curve — both what Jon McCormack calls’ two sets of metadata ‘.
there are actually three sets of metadata in the videos that the iPhone 12 records. We don’t know yet what their respective USES are.
as of press time, no more information about ‘Dolby Vision Profile 8.4’ and ‘new Dolby Vision API’ on iOS, macOS, and tvOS could be found.
----------------------------------------------------
Link to the original webpage. Also, here's the Dolby Vision profiles document directly from Dolby.
My conclusion is that the TV I have (LG C7P 2017 series) does not support the new DV profile - dvhe.08.04 so it falls back to HLG and I am unable to see the full curve with this TV. New TV's with the proper support, we should see in better curve.
However, this still does not answer why ATV4k won't AirPlay these videos at least in HLG format. My guess is that ATV4K does not support HGL HDR currently. Maybe on future updates. I think I am done investigating this..
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