LG Smart TV Remuxing causing black screen with audio

[TheViceroy771]

Describe The Bug
I have a LG Smart TV which is using the official store app to access my Jellyfin server. Most things play just fine, but there is an issue when it comes to some HEVC Main 10 content. Sometimes it plays fine, others it plays audio with no video and sometimes it plays audio/video but if the content is paused or skipped forward/back it completely stops playing and you must reset the content from the beginning.

• I have messed around a bit with the LG Smart Tv xml file and added ‘hevc’ to the direct play profiles, but that did not solve the problem. Also, I specifically looked up my tv model and confirmed that it could play HEVC 10 bit content, which is listed in the video codec specs.
• There does not seem to be any correlation to video resolution, it is an issue with 1080p and 4k content, seemingly at random.
• I have already disabled the ‘Prefer fMP4-HLS Media Container’, though that does not seem to have changed anything.

I have confirmed for all of the media listed in this thread (that has issues) Jellyfin is remuxing, however for whatever reason the remuxing is going from .mkv back into .mkv. I started going deeper into why these files are remuxing, but I can’t find anything obviously linking them together. Somethings that might be the case though:

• There is a disclaimer in LG’s documentation that states “Video files created by some encoders may not be played.” I have not found a comprehensive list of what video encoders are valid and which aren’t but as an example here is the encodings for the media that is listed in this thread.
• Media 1 Source encoding: Lavc58.134.100 libx265
• Media 2 Source encoding: Lavc60.31.102 libx265
• Media 3 Source encoding: Lavc60.31.102 libx265

I also found that for media Jellyfin remuxes seems to default the encoding output using: Lavf60.3.100. I can not verify if this encoding version is compatible with LG, but it might not be so that could be the issue.

• I also checked a working file (.mkv, hevc, SDR) that did not trigger the remuxing and found its encoding to be: Lavc61.3.100 libx265

I also tried disabling the “Allow video playback that requires conversion without re-encoding” option and all the media that had been remuxing entirely failed to playback. It didn’t start or play audio or anything, just gave the error message and closed. So it appears the remuxing is necessary and is doing something.

What I really don't understand is why the remux is going from .mkv back into .mkv and why it is still causing playback issues. Has anyone else had this problem?

Lastly, this exact same media plays correctly via Plex on the exact same TV, so I cant help but think it has something to do with the app itself.

Media Information
Media 1 Jellyfin Logs:

• https://pastebin.com/MZV02aPN

Media 1 FFmpeg Logs:

• https://pastebin.com/Jw0wRpf8

Media 2 & 3 Jellyfin Logs:

• https://pastebin.com/akEeXHXu

Media 2 FFmpeg Logs:

• https://pastebin.com/yndp48n8

Media 3 FFmpeg Logs:

• https://pastebin.com/yu8R4T8F

Screenshots
Not Applicable

System (please complete the following information):

• Server Platform: Linux
• Client Platform: LG Smart TV
• Browser: WebOS: 6.4.0-21 and the app is up to date.
• Jellyfin Version: 10.9.11

Additional Context
I also opened up a ticket on the jellyfin forums: https://forum.jellyfin.org/t-lg-smart-tv-jellyfin-app

[dmitrylyzo]

however for whatever reason the remuxing is going from .mkv back into .mkv.

Remuxing to MKV was dropped in 10.8: #4385

Could you enable debug logging on the server, start playback and look for DeviceProfile in the Jellyfin log?