HEVC Target Transcoding - Testing several machines with test to 4K 20mbps output

I've been testing various machines with the same workload today, and then checking Tautulli as well as playback quality to see what's up.

My files are 4k UHD disk rips I made myself with MakeMKV. I started testing with several different files, but everything seemed consistently the same so I'm only posting results here using my trusted copy of 1917 which I STILL HAVE NOT WATCHED all the way through. For shame. It has a 77mbps video track, which is on the higher end for my 4k files that average around 65mbps.

Client is Plex App on Windows 10 with an HDR display. Transcoded output is showing as HDR and looks f'n fantastic. App's quality is set to 1080p at 20mbps, which results in 4k 20mbps HEVC output.

Unless noted, machines are on Ubuntu 24.04.1 LTS, all machines are transcoding to RAM or SSD's for the temp directory, and the Plex chart for RAM usage barely moves the line indicating Plex's usage:

  • i7-6700 6th gen (Win 10) LOL, no fam. HEVC toggle doesn't even show up in settings.
  • Celeron G4930 9th gen 0.6x Buffering quite a bit.
  • i9-9900 9th gen 1.0x Juuuuust barely making it work.
  • i7-9750H 9th gen (Win 10) 0.5x I'm wondering if the HDR Tone Mapping feature is involved and causing issues here.
  • 1660ti GPU 4.1x This is in the 9750H laptop.
  • J4125 ~10th gen 0.6x With more than occasional buffering. This is not a Synology NAS, but is the same CPU is the models that get recommend here a lot. Oddly, worse than the G4930 despite the speed being the same.
  • N5105 11th gen 1.4x Ok, what the fuck?
  • N100 12th gen 0.9x With occasional buffering. Bumps up to 1.0x briefly. This is my actual server an AOOSTAR R1.
  • Shield 2017 Wont even do in HW. The setting is there though? Weird. I was hoping for some magic.
  • Shield 2019 Same. BOOO.

A couple of observations:

  • None of the testing had CPU going nuts when HW was being used correctly. Consistently very low. 15% was the highest I saw on any machine.
  • For some other testing I did with a browser, the colors for HEVC SDR output do appear to be Tone Mapped correctly just like H264 SDR output from an HDR source. Not a surprise.
  • It doesn't seem like there's a performance difference between the output being HEVC HDR or HEVC SDR Tone Mapped.
  • The performance difference for the 9th gen CPU's was a surprise. All testing I've ever done with those CPU iGPU's transcoding to H264 has always been virtually identical.
  • The 1660ti kicking ass is pretty rad. I'm wondering how consistent that will be across various Nvidia GPU's.
  • The N5105 being the stand out iGPU performer is wild. What the hell?
  • Yes, there is a distinct lack of newer desktop CPU's in my arsenal. I might need to change that soon.