Hardware acceleration with VAAPI works fine, but QuickSync Video doesn't

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[attachment=4891][attachment=4891]
Playing any video that requires transcoding with QSV enabled fails with error "playback failed due to a fatal player error". VAAPI works fine though and I've verified that hardware transcoding with VAAPI works using intel_gpu_top.

• Intel Core i5-12500
  
• NixOS 24.05
  
• Custom jellyfin-ffmpeg is being used
  
• No virtualization is being used, Jellyfin runs on bare-metal
  

I have the following drivers and settings enabled:

Code:

    {
      hardware.opengl = {
        enable = true;
        extraPackages = with pkgs; [
          intel-compute-runtime
          intel-media-driver # LIBVA_DRIVER_NAME=iHD
          intel-ocl
          libvdpau-va-gl
          onevpl-intel-gpu # For NixOS <= 24.05
        ];
      };
      boot.kernelParams = [ "i915.force_probe=4690" ];
      environment.sessionVariables = { LIBVA_DRIVER_NAME = "iHD"; }; # Force intel-media-driver
    }

See the attached image for my QSV settings in Jellyfin. If more information is needed please let me know.