Blackfyre wrote:However, I thought MPC + Madvr already supports HDR? Madvr certainly has the settings for it under the display settings.
No Madvr dosen't yet support HDR output.
What it does support is a very high quality HDR to SDR conversion, so you can watch HDR clips on a non HDR connection with some retained quality enhancement to the SDR version of the clip. If you crank up your backlight(for LCD screens)/OLED light setting and tune madvr's HDR conversion setting for it.
But for some reason madvr and LAV filter dosen't pick up the HDLeaders releases as being HDR BT.2020 files, as it does work with the various demo-uhd3d.com files correctly. I don't know why.
The right media info metadata seems to be included in the mkv.
The HDLeader releases is reported to work on LG HDR 4k and Samsung HDR 4k screens inbuilt players.
One tricky thing is that some releases have ATMOS audio, and at least the LG's can't play that so you will have to remux in som lesser & supported audio track from another release.
As far as i think it works is, HDLeader uses Zeus BT.709 WCG 4k releases and then reinserts the HDR curve with the SMPTE ST2086 static metadata in the mkv somehow.
But i really don't know how he does it, he reveal some info if you read the comments in the 1337x site, but it is really not much to go on.
I don't have access to a real UHD-BR discs or a player, but i have tested a HDR BT.2020 HDLeader release and a "normal" 4k BT.709 Zeus release of the same movie (Mad Max).
And.......it looks AMAZING 
The HDR mkv does activate the HDR function on a compatible LG TV and it does look better (much more intense from the HDR on anything bright and much wider colour palette from the WCG features) than the straight 4k 10 bit 4:2:0 BT.709 Zeus rip. And just the straight Zeus rip looks already more than great. But HDR + WCG on top of that is an whole other level.
I have checked out several of the releases and i think it is legit as far as 4k HDR UHD Rip. Of course i can't compare with the real disc.
The day madvr or another renderer/player with high grade chroma upsampling & 3D lut support + SVP supports HDR output through the new HDR windows 10 interface/API, it will look better than any UHD-BR standalone player can offer 
And I still hold a hope that madshi will add vaporsynth interface one day to madvr.
So bottom line, if you have a HDR screen and no UHD-BR disc or player.
YOU have to try it out it will blow you away 
Of course depending on how good the screen is though.
The general consensus seems to be, anything LG 4K OLED panel based (LG/Loewe/Panasonic) is the best, then the various high end Samsung and Sony FALD LCD screens and then everything less begins to be less impressive for maximum HDR dynamic range impact.
In terms of maximum contrast and highest light output that the screens can support.
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EDIT update
I checked these HDLeder 4K BT.2020 with HDR releases some more.
And unfortunately there is some problems with them.
He has used Zeus normal BT.709 4k UHD release and reinserts the HDR curve with the SMPTE ST2086 static metadata in the mkv.
But he also expands the normal compressed BT.709 gamut to WCG DCI BT.2020.
And the result is over saturated colors 
On an LG TV you can switch the Color gamut to standard from wide and it will look right again but still with glorious HDR.
This should be possible in madvr if madvr support HDR output in the future also.
