Some 4k HEVC files don't engage HW decoding and appear to revert to SW decoding

Plex Media Server
1

I’m having an odd issue. I’m working on a dedicated hetzner ex42 server and am running into an odd issue. This server is running a 7700k intel processor, so it should have no problem supporting hw decoding. However, I’m noticing that with some 4K content, the CPU gets absolutely pegged at 100%. Using the intel-gpu-tools package to monitor gpu usage during playback, I see that the gpu is in fact inactive during playback of these videos. Upon playing other 4k content, the GPU is fully engaged as expected. Digging into the Plex logs during playback of the files in question, I noticed some errors right at the beginning of the transcode that may shed some light:
[Transcoder] [Parsed_scale_vaapi_1 @ 0x1a5ec00] Failed to start picture processing: 1 (operation failed).
[Transcoder] Error while filtering: Input/output error
[Transcoder] Failed to inject frame into filter network: Input/output error
[Transcoder] Error while processing the decoded data for stream #0:0

Do these seem relevant to the issue at hand? Is there anything I can dig into further to troubleshoot this? Much appreciated!

Server Version#: 1.19.3.2852
Player Version#: 7.0 (iOS)

2

There’s a number of transcoding tasks which cannot be done/handled by hw transcoding – this is mostly about burning in subtitles to your video stream.

3

If you would share the info on these files, one could guess why that happens.

4

Here’s an example of one that doesn’t use HW. Subtitles are turned off. Does this give you any insight? Appreciate the reply!

Media

  • Duration 1:20:43
  • Bitrate 15980 kbps
  • Width 3840
  • Height 2160
  • Aspect Ratio 1.78
  • Video Resolution 4K
  • Container MKV
  • Video Frame Rate 24p
  • Video Profile main 10

Part

  • Duration 1:20:43

  • File Randomfile.mkv

  • Size 9.01 GB

  • Container MKV

  • Indexes sd

  • Video Profile main 10

  • Codec HEVC

  • Bitrate 15980 kbps

  • Language English

  • Bit Depth 10

  • Chroma Subsampling 4:2:0

  • Coded Height 2160

  • Coded Width 3840

  • Color Range tv

  • Frame Rate 23.976 fps

  • Height 2160

  • Level 5.1

  • Profile main 10

  • Ref Frames 1

  • Width 3840

  • Display Title 4K (HEVC Main 10)

  • Codec EAC3

  • Channels 6

  • Language English

  • Audio Channel Layout 5.1(side)

  • Sampling Rate 48000 Hz

  • Display Title English (EAC3 5.1)

  • Codec SRT

  • Language English

  • Title English

  • Display Title English (SRT)

5

Interesting - I didn’t know that…thanks! In this case though, I’m not doing anything with subtitles - they are set to “None” in playback.

6

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