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Plex Transcoding 4K HDR10 to 1080p Falls Back to CPU After a Couple Seconds (Nvidia RTX 2070 Super)

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Problem: Transcoding from 4k HDR10 to anything else will trigger the GPU for a moment then it falls back to CPU.

 

Unraid: 7.0.0

GPU: Nvidia RTX 2070 Super

Nvidia Driver Version: 565.77 (multi-transcode unlocked with patch)

Plex Version: 1.41.4.9463 (running in Docker with GPU passthrough confirmed working)

 

Details:

- Plex will successfully transcode multiple 1080p to 720 or any other resolution and shows these transcodes working from the CLI when I run 'watch nvidia-smi'

- The 'watch nvidia-smi' monitor will show the Plex transcode briefly when attempting to transcode from 4k HDR to 1080p but after a few seconds the GPU transcode will fall back to CPU and it will disappear from the GPU monitor.

- I have tested with both Dolby Vision and non-DV HDR videos.

- I have tested with HDR mapping on and off in Plex settings.

- Plex is correctly configured to use the Nvidia GPU, shows the proper GPU in the settings, and successfully transcodes 1080p videos using the GPU.

 

Has anyone else been able to get their NVIDIA RTX GPU to transcode from 4k HDR to 1080p? If so, do you have any suggestions for me as to why it keeps falling back to CPU on my machine? I have done extensive searching here and after many hours have been unable to find a solution.

 

Thank you for your time reading this.

  • Community Expert

in plex setting, make sure the nvidia gpu is selected and not set to auto

  • Author
On 2/15/2025 at 4:36 AM, bmartino1 said:

in plex setting, make sure the nvidia gpu is selected and not set to auto

The GPU is set instead of auto. Non-HDR transcoding works fine.

 

Thank you for the response. Do you have any other ideas?

  • Community Expert

Plex has had issues for years with HDR transcoding (tone mapping).  Probably an application issue to ask at the Plex forum.  It seems every few Plex updates they break it, then spend a couple releases getting it work.  Only to break it again.

 

You can try rolling back to a previous version of Plex (ideally one that is known have HDR tone mapping work correctly).

  • Author
2 hours ago, ConnerVT said:

Plex has had issues for years with HDR transcoding (tone mapping).  Probably an application issue to ask at the Plex forum.  It seems every few Plex updates they break it, then spend a couple releases getting it work.  Only to break it again.

 

You can try rolling back to a previous version of Plex (ideally one that is known have HDR tone mapping work correctly).

Oh okay, that's good to know. I was unaware they it keeps breaking. I'll check in with the Plex forums. Thank you!

  • Community Expert

Unfortunately Plex has a history of breaking things as they release new features.  :(

  • 2 months later...
On 2/16/2025 at 7:51 PM, wizenthorne said:

Oh okay, that's good to know. I was unaware they it keeps breaking. I'll check in with the Plex forums. Thank you!

Did you ever find a solution for this? I am having a very similar issue where I can't gpu transcode most of my library (in 4KHDR10).

  • Community Expert

Plex has been in and out with release..

It work in x build breaks in next. its more trial and error.

 

I've found theses pelx transcode to be bvest when pared with a nvdia GPU

 

image.png.626fffb0730ef97026daa19ca8675da9.png

 

image.png.ac80ff889e34593ae4207af4f560456a.png

 

if you want GPU only be sure to take hadware transcoding device off auto and set to the nvidia GPU

image.png.f5bd0a0d7822bb9e6c5cbbed9544ee7d.png

 

 

1 hour ago, bmartino1 said:

Plex has been in and out with release..

It work in x build breaks in next. its more trial and error.

 

I've found theses pelx transcode to be bvest when pared with a nvdia GPU

 

image.png.626fffb0730ef97026daa19ca8675da9.png

 

image.png.ac80ff889e34593ae4207af4f560456a.png

 

if you want GPU only be sure to take hadware transcoding device off auto and set to the nvidia GPU

image.png.f5bd0a0d7822bb9e6c5cbbed9544ee7d.png

 

 

Yep, that's how I have it. I also have an RTX 2080 Ti that I use exclusively for transcoding

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