PGS Burn In causes HW transcoding to fail only with HEVC SDR

Plex Media Server Desktops & Laptops
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Server Version#: 1.41.0.8994
Player Version#: 4.139.0

OS: Ubuntu 24.04.1
Server: Offical Plex Docker Contaner
CPU: Intel N100
RAM: 16GB

This is a strange problem I have encountered since the last 2 Server updates that added “Improved subtitle burn-in performance when Hardware Transcoding (PM-1764)”

HW Transcoding fails when PGS subtitles burn in and falls back to CPU only.

The strange thing is VOSUB another picture-based subtitle format is correctly using HW Transcoding perfectly, Furthermore AV1 with PGS Burn in & HEVC with HDR tone-mapping also correctly transcode with PGS sub burn in.

Only SDR HEVC files that need PGS burn in cause HW transcoding to fail.

As you can see in this screenshot Hardware Transcoding is 100% working as expected with a range of video codecs and subtitle types including burn in, I am using web browsers to test as they are the only clients I have that force subtitle burn in.

No-PGS
No-PGS729×686 116 KB

Now when I enable PGS subs on the SDR HEVC files HW transcoding fails and reverts to Software Transcoding pegging the CPU to 100% as expected, This happens on all HEVC SDR files that require PGS Burn in.

PGS-subs
PGS-subs851×588 90 KB

The Server logs give a strange OOM error every time the HEVC SDR files PGS Burn in.

Console Log
Console Log2622×262 106 KB

Has anyone else experienced this? its a very difficult issue to explain and I have only seen one other post on this forum with the same issue but the OP never followed up.

As for the full log file is there a way to provide it privately? as it contains my public IP

I understand this is very rare issue so thank you in advance!

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Going to need the full Server DEBUG logs preceding and following those messages.

It’s not possible to know what’s happening at that particular instance.

I will open a PM for you to submit your full DEBUG logs.

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Did you ever find out the reason for this?! I’m having this same issue, only it happens randomly with PGS subs, and with x264 files too. I’m on the latest Plex public release on Ubuntu 22.04

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The wonderful ChuckPa worked with me to test this over DMs and it seems to be an issue with the current transcoder,

They suggested to me to update to the new transcoder preview as it has many fixes

However I have been too busy with real life to test it :frowning:
If you are so inclined give it a try and let me know if you have any success!

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