How to convert Dolby Vision HDR to HDR10+?

Question

I'd like to convert a file recorded from an iPhone 12 to a royalty-free version (for upload to Wikimedia, Flickr, etc). So the transfer involves:

Source (iPhone proprietary-encumbered)	Destination (royalty-free)
4k 60fps (UHD, not DCI)	4k 60fps
BT.2020 in HLG (WCG)	BT.2020 in HLG (WCG)
Frame-level dynamic HDR metadata in Dolby Vision profile 8.4	Frame-level dynamic HDR metadata in HDR10+
HEVC	VP9 (open to AV1 as well but that's likely more nascent)
Bitrate is 31 Mb/s	Fine with higher bitrate to maintain same SSIM/PSNR
Audio is in AAC	Audio to Vorbis/OGG

According to https://codecalamity.com/encoding-uhd-4k-hdr10-videos-with-ffmpeg/ it should be possible to do most of this. Anyone can help me cook up the right command for this?

Answer 1

Sadly no, not without expensive specialist broadcast processing hardware.

From the Reddit link,

Dolby Vision is 100% proprietary. There is no incentive at all for Dolby to convert anything to HDR10+ to help out Samsung users (and pre-2019 Panasonics) when the only reason HDR10+ exists is because Samsung didn’t want to pay Dolby for the license.

Dolby Vision is simply an enhancement layer on top of HDR10 which is the base layer. There are a couple types of DV layers. The MEL (minimum enhancement layer) and the FEL (full enhancement layer) which reconstructs the original 12-bit signal. The FEL is what gives DV a large advantage over HDR10 and HDR10+.

Page 12:

https://www.dolby.com/us/en/technologies/dolby-vision/dolby-vision-for-creative-professionals/dolby-vision-uhd-bluray-authoring-workflow.pdf