I’m going to investigate this.
I’m tied up most of Monday. I’ll get on this ASAP.
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Thanks. I’d be happy to help any way I can tho my knowledge of this subject is limited.
Thanks, but this is going to be a gnarly one.
I need to setup some special tooling to get in and watch what’s happening.
I will prepare another sample later.
But just to clarify, this problem seems to be independent of any specific Movie. It happens for all my 4K HDR Movies when transcoding and tone mapping.
Have you seen this thread? Hardware transcoding stopped working on Synology NAS - #15 by oh7vm
It sounds like the person had a similar issue and solved it by rolling their plex docker container back to an older version.
Great to hear you’re making progress. Is this related to the issue I mentioned in this post (Plex (Docker) HDR Tone Mapping not working anymore (hw) - #12 by TrntRzr1911) or should I be making a separate topic for this?
I have recreated no tone mapping in Docker.
– which is this thread’s topic 
Sorry, I misread.
I’ve found one issue.
PLEASE VERIFY – the PLEX_UID/PLEX_GID of the container is a member of the group which owns /dev/dri
I have used the following to create the Plex docker image (for this config you have to be a plexpass member):
docker run
-d
–name plex
–network=host
-e TZ=“Europe/Amsterdam”
-e PLEX_CLAIM="yourplexclaim-code”
-e PLEX_UID=“userid”
-e PLEX_GID=“groupid”
-e PLEX_PASS=yes
-e UMASK=002
-e DEBUG=no
-v /etc/localtime:/etc/localtime:ro
-v /volume1/docker/plex:/config
-v /volume1/docker/plex:/transcode
-v /volume1/Media:/data
–device=/dev/dri:/dev/dri
plexinc/pms-docker:plexpass
You have to look up the UID and GID of the user which has rights on your Media folder and the docker-plex-config folder. And offcourse change the folder mapping to your own folders.
The “–device=/dev/dri:/dev/dri” parameter gives you HW acceleration. Without that line 4k HDR 40Mbit is non watchable if it needed transcoding on my 920+. With the line in place it doesn’t even breaks a sweat.
INFO: I have merged your posts from the other thread here for continuity sake
Do you have the Synology GUI equivalent or did you do all this on the Synology command line?
How to do this goes beyond my knowledge level of the DSM GUI.
Synology command line indeed. I tried to do it through the GUI but couldn’t get HW working that way.
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Thanks for confirming. That’s how I use it as well on Syno.
Command line is very easy and the same info you need to put into the gui you put in the docker command above.
You folks mind if I duck out ?
I need to move on to other bugs.
I think @Alain13 can provide that last little bit of trick education?
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Yeah no problem ChuckPa, you do your thing 
If you go to docker → container → settings → export can you tell me how the beginning of the then created settings file looks? In my settings file, there is a devices entry but it has the value “null”, which I think is wrong:
“cpu_priority” : 50,
“devices” : null,
“enable_publish_all_ports” : false,
I wonder if it might be possible to export the setting file, edit that to include “–device=/dev/dri:/dev/dri” parameter and then import it again.
