I have been trying to fix this issue since I got a new HDR TV hooked up to my Mac Mini M4 (Sequoia) on Black Friday.
I can play HDR using the Plex app on my LG TV (awkward!), Using the Plex media server through Chrome it looks great (but no multi channel audio), However it looks terrible in Plex app and Plex HTPC! I also need the Multi Channel output to my receiver to work, so browser viewing is not an option.
I just want to use Plex HTPC like I have for close to a decade, but just to be able to view HDR content and not have it look terrible on my new TV.
Basically Plex app and Plex HTPC run on mpv, an open source media player easily capable of playing beautiful HDR video on Mac. HDR10 content looks great in Plex Media Server playing in Chrome, Movist, Infuse, IINA (runs on MPV 0.35), and MPV (0.39.0) with the below settings added to mpv.conf.
cocoa-cb-output-csp=bt.2100-pq
hwdec=auto
target-peak=1600
target-prim=bt.2020
target-trc=pq
vo=libmpv
Thankfully Plex developers made it easy to edit the mpv.conf inside of ~/Library/Application Support/Plex (or Plex HTPC)/, I thought adding the same configuration there would do the trick but no dice. Through trial and error I found that vo=libmpv just breaks playback with an error message, I think Plex is forced to use vo=gpu. The magic line cocoa-cb-output-csp=bt.2100-pq only works with the latest mpv (vo=libmpv), and target-colorspace-hint=yes does nothing at all.
Is there a magic mpv command I am missing that will enable HDR in Plex and Plex HTPC on Mac? It should be trivial as mpv 0.39 can do it, as well as IINA which is running mpv 0.35. Why leave this as Windows only feature? It works through Chrome on Mac, other mpv based players, just NOT Plex or Plex HTPC??!!
PS - I also tried replacing the libmpv.2.dylib based this guide by installing mpv via homebrew and replacing the libmpv.2.dylib inside of the Plex app, but that just broke Plex (the new one is also 3.6 Mb vs 13 Mb on the original?)
Screenshot below for comparison, PMS through Chrome and Safari look just like IINA, Plex App is identical to Plex HTPC.
