*Not ToneMap Issue* HEVC Transcode Problems

[scarbrtj.e]

Server Version#: 1.43.1.10611
Player Version#: Chrome Windows 4.159.0

If playing back 4K HDR HEVC files and transcoding to H264 12Mbps 1080p, the playback looks good. PMS is choosing to hand this client SDR, which is good, as the client can’t handle HDR.

If playing back 4K HDR HEVC files and transcoding to HEVC 12Mbps 1080p, the playback looks bad (too dark, color generally “OK”). PMS is choosing to hand this client HDR, which is not good, as the client can’t handle HDR.

So the culprit imho is PMS behavior when HEVC transcoding is enabled. If I have HEVC transcoding enabled and play back on AppleTV/HDR TV e.g., AppleTV can handle the 1080p HDR fine and it looks good.

My problematic clients for 4K HEVC HDR → 1080pHDR are Chrome, and iOS. I can’t see that there is a way to tell PMS to make 4K → 1080p HEVC be SDR consistently or as appropriate for a client.

So the question: if HEVC transcoding is on, will it always be HDR->HDR if the source is HDR… it will never tonemap to SDR? H264 transcodes just always go SDR it seems… and that is my “fix” but sure I’d prefer HEVC transcodes.

I will tag @OttoKerner 'cause he usually knows about these things!

[scarbrtj.e]

Plex admins?

[chris_decker08]

PMS will tonemap if the client reports that it does not support HDR. This leads me to believe this is a client issue.

[scarbrtj.e]

Thanks. What do you think I could change at the client level. Basically just playing back in Chrome… looks too dark (as seen above). Again it’s not like a typical tone map issue (that we all experienced a bit in the not too distant past!). PMS giving 1080p HDR transcode on AppleTV playing on an HDR TV looks great! But I agree it’s kind of a client issue. However is it the case that HDR source always transcodes to HDR no matter what if HEVC is enabled? That seems to be what I’m seeing. If so, problematic.

[chris_decker08]

Right now that appears true for the web client only. Unfortunately this is not something we can address in pms itself and I have filed a ticket for a client engineer to take a look at.

[scarbrtj.e]

Thank you Chris. I notice similar such behavior on iPhone too. The HEVC transcode to a lower resolution still kicks in HDR, but the H264 SDR alternative looks substantially better (brighter)…

H264 20Mbps:

HEVC: