Setting up Intel Arc Pro B50 for Plex Transcoding inside LXC (Without SR-IOV)

[devedse]

Hey all,

I just got my new MinisForum MS-A2 with an Intel Arc Pro B50 which I'd like to setup for Plex Transcoding.

I currently run a cluster of 2x N100 nodes and the new MS-A2.

Previously I simply passed the /dev/dri/renderD128 into the LXC container which allows Plex to use it to Transcode on the N100.
I then migrated the LXC container to my new MS-A2 where the /dev/dri/renderD128 is the B50. In Plex\Settings\Transcoder the card then shows up:


However when doing a transcode it seems to fallback to CPU rather then GPU.

I wanted to ask if someone else has been able to get this to work yet?

P.s. I did also see Wendell's research into getting SR-IOV working for the B50, but I'd rather wait for all drivers to be a bit more stable until I'll follow that path. From what I heard was that with SR-IOV, people also had issues with Transcoding on Plex on the B50.

 

[devedse]

Here's some logs I found in the plex container. It seems it's not able to open the hardware device:

Oct 15, 2025 14:12:56.752 [135476236794680] DEBUG - [Req#1f30a/Transcode] Streaming Resource: Calculated bandwidth of 21270kbps exceeds bandwidth limit. Changing decision parameters provided by client to fit bandwidth limit of 20000kbps
Oct 15, 2025 14:12:56.752 [135476236794680] DEBUG - [Req#1f30a/Transcode] Streaming Resource: Determining preferred transcode encoders through transcode only decision.
Oct 15, 2025 14:12:56.752 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: testing hevc (decoder) with hwdevice vaapi
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: hardware transcoding: testing API vaapi for device '/dev/dri/renderD128' (Intel Battlemage G21 [Intel Graphics])
Oct 15, 2025 14:12:56.753 [135476236794680] ERROR - [Req#1f30a/Transcode] [FFMPEG] - libva: /config/Library/Application Support/Plex Media Server/Cache/va-dri-linux-x86_64/iHD_drv_video.so init failed
Oct 15, 2025 14:12:56.753 [135476236794680] ERROR - [Req#1f30a/Transcode] [FFMPEG] - Failed to initialise VAAPI connection: 18 (invalid parameter).
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: hardware transcoding: opening hw device failed - probably not supported by this system, error: I/O error
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Could not create hardware context for hevc
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: testing hevc (decoder) with hwdevice vaapi
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: hardware transcoding: testing API vaapi for device '/dev/dri/renderD128' (Intel Battlemage G21 [Intel Graphics])
Oct 15, 2025 14:12:56.753 [135476236794680] ERROR - [Req#1f30a/Transcode] [FFMPEG] - libva: /config/Library/Application Support/Plex Media Server/Cache/va-dri-linux-x86_64/iHD_drv_video.so init failed
Oct 15, 2025 14:12:56.753 [135476236794680] ERROR - [Req#1f30a/Transcode] [FFMPEG] - Failed to initialise VAAPI connection: 18 (invalid parameter).
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: hardware transcoding: opening hw device failed - probably not supported by this system, error: I/O error
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Could not create hardware context for hevc
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Streaming Resource: Reducing playback quality for 19047kbps stream bitrate: video resolution to 1920x1080, audio channels to 2, quality to 85
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: testing hevc (decoder) with hwdevice vaapi
Oct 15, 2025 14:12:56.753 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: hardware transcoding: testing API vaapi for device '/dev/dri/renderD128' (Intel Battlemage G21 [Intel Graphics])
Oct 15, 2025 14:12:56.753 [135476236794680] ERROR - [Req#1f30a/Transcode] [FFMPEG] - libva: /config/Library/Application Support/Plex Media Server/Cache/va-dri-linux-x86_64/iHD_drv_video.so init failed
Oct 15, 2025 14:12:56.753 [135476236794680] ERROR - [Req#1f30a/Transcode] [FFMPEG] - Failed to initialise VAAPI connection: 18 (invalid parameter).
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] Codecs: hardware transcoding: opening hw device failed - probably not supported by this system, error: I/O error
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] Could not create hardware context for hevc
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] MDE: Selected protocol dash; container: mp4
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] MDE: analyzing media item 1210
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] MDE: MyFunnyHomeMadeVideo: Direct Play is disabled
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] MDE: MyFunnyHomeMadeVideo: media must be transcoded in order to use the dash protocol
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] MDE: MyFunnyHomeMadeVideo: no direct play video profile exists for http/mkv/hevc
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] MDE: MyFunnyHomeMadeVideo: no direct play video profile exists for http/mkv/hevc/truehd
Oct 15, 2025 14:12:56.754 [135476236794680] DEBUG - [Req#1f30a/Transcode] MDE: MyFunnyHomeMadeVideo: no direct play video profile exists for http/mkv/hevc/ac3