Plex is (incorrectly) transcoding 4K --> 1080p ... HELP!

I have a new Plex Media Server running on this hardware:

  • Platform: AMD Threadripper TRX40 ATX
  • Motherboard: Asus Strix TRX40-XE
  • CPU: AMD Ryzen Threadripper 3960X 3.8GHz 24 Core 280W
  • Ram: 4x Crucial DDR4-3200 32GB (128GB)
  • Video Card: NVIDIA RTX A5000 24GB PCI-E
  • Sound Card: Onboard Sound
  • Networking: Integrated WiFi+Bluetooth
  • Storage: Hard Drive
  • Samsung 980 Pro 2TB Gen4 M.2 SSD
    • Comments: Primary drive.
  • Samsung 980 Pro 2TB Gen4 M.2 SSD
    • Comments: Secondary drive.
  • Samsung 980 Pro 2TB Gen4 M.2 SSD
    • Comments: Tertiary drive.
  • CD / DVD: Asus 16x Blu-ray Burner SATA (black)
  • Case: Fractal Design Define 7
  • Power Supply: Super Flower LEADEX Platinum 850W
  • CPU Cooling: Noctua NH-U14S TR4-SP3
  • Additional Cooling: Case Fans Upgrade Kit (PWM Ramping)

I’m trying to watch a UHD Video (Venom) on my Roku, which is directly wired into a gigabit switch, and Tautulli is reporting that its transcoding 4K HEVC down to 1080p … I have the Roku set to play the original quality (with no restrictions on the Plex side) … but it both gets transcoded down to 1080p and also dies after only a few minutes, saying “Your server was not powerful enough to convert the video for smooth playback” … first, the audacity (LOL), second – I should have enough power to raise the Titanic with this thing … I don’t understand whats going on.

Plex is installed on an M.2 Gen4 SSD, and the Venom file is also living on an M.2 Gen4 SSD (separate disk).


Tautulli_Info_Venom

It looks like PGS subs are enabled. The Roku cannot natively render image based subs, so a video conversion is required to burn them in. You can either disable the subtitles or find another variant, like SRT subs.

1 Like

The same issue with subs turned off. Additionally, it still craps out just a few minutes in saying “the server wasn’t fast enough to convert for smooth playback”. I have hardware acceleration checked and a GPU meant for freaking space travel … any idea why I would still get a message like that?!

Tautulli_Info_Venom2

Which Roku model is it?

Roku Ultra:

https://www.roku.com/products/roku-ultra

So, it should handle it just fine.

Change from truehd to ac3 - it can’t handle the truehd audio

1 Like

No, same.

Tautulli_Info_Venom3

My only other guess is that the Roku Ultra can’t handle x265?

Maybe it does not support Dolby Vision profile 7?

Do you have any media that is HDR10 only, without Dolby Vision?

Supported video codecs: Roku

Hardware specifications: Roku

1 Like

Well, the first thing that jumps out at me is the video bitrate. This movie is 60+ and the Roku says it supports no higher than 40.

What bitrate technically specifies something as 4K? I mean, I know 2160p, but if you get something at that resolution and 12MB/s – is it really a 4K movie?

HEVC 4K encodings

Roku recommends HEVC for UHD encodings. Roku 4K devices support HEVC up to level 5.1 and bitrates up to 25Mbps.

https://developer.roku.com/docs/specs/media/streaming-specifications.md#hevc-4k-encodings

Bitrate and resolution are independent of each other.

Netflix, et al stream 4K video at ~25 Mbps. I’ve Blu-ray HD SDR rips that are 40+ Mbps.

Good catch.

You might look in the Roku log files.

The Plex Samsung app logs show when bitrate is exceeded. Roku might do the same (I don’t have one with which to test).

https://support.plex.tv/articles/categories/player-apps-platforms/roku/

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.