Hardware transcoding fails for 4k movies

[pau999 0]

Hi,

I have a video with the following format: 

 

When I try to watch this from my phone at a lower resolution of 1080p the transcoding fails with the following error:

14:37:01.263 [hevc_qsv @ 0xbe2c80] Error initializing the MFX video decoder: unsupported (-3)
14:37:01.263 Error while decoding stream #0:0: Function not implemented
14:37:01.263 [hevc_qsv @ 0xbe2c80] More data is required to decode header

This is happening once I changed the server to use advanced hardware transcoding with intel quick sync. I set up the server in a docker container and followed the steps provided in the link: https://emby.media/docker-server.html

Specifically, added GIDs to GIDLIST using the command

getent group video | cut -d: -f3
getent group render | cut -d: -f3

and also added this to my docker compose file.

    devices:
      - /dev/dri:/dev/dri # VAAPI/NVDEC/NVENC render nodes

 

However when I turn off the hardware acceleration, it does work. Attaching the logs.

ffmpeg-transcode-1d5ddbc5-fccb-487a-9c91-4fd42f875788_1.txt embyserver.txt

[Luke 40114]

Hi, for comparison purposes, are you able to test our native package for Ubuntu and see how that compares? Thanks.

[pau999 0]

Sure, Will do that. But another thing I noticed is when I set to just VAAPI, it works.

[pau999 0]

Checked the native package for ubuntu and i find the same error during transcoding

[Luke 40114]

On 4/3/2024 at 4:06 PM, pau999 said:

Checked the native package for ubuntu and i find the same error during transcoding

HI, can you please attach the emby server log, ffmpeg log file and hardware detection log files from then you did that? Thanks !

[Q-Droid 881]

Your Skylake CPU (6th gen) is right on that edge where it might be able to partially handle HEVC 10-bit in HW but not HDR. Not sure how that's handled in the current drivers and whether HW detection was right or wrong to attempt it.

 

 

[softworkz 4570]

On 4/3/2024 at 7:18 PM, pau999 said:

Sure, Will do that. But another thing I noticed is when I set to just VAAPI, it works.

Probably it falls back to sw transcoding in that case, can't say for sure without a log, but VAAPI doesn't indicate support for 10bit deccoding, as seen in the log.

Memory has darkened a bit, but unless I misremember, the situation was like this:

• SkyLake didn't have fixed-function implementation for HEVC 10bit decoding
• But Intel had a special solution for QSV: There was a special implementation for HEVC hw decoding via an extension dll, which ffmpeg could load
  It's hw decoding, but using GPU kernels/shaders for decoding instead of fixed-function blocks
• The dll was included in Intel Media SDK (Windows) and later in Windows drivers
• For Linux, it was included in Intel Media Server Studio, but opposed to Windows this wasn't free
• Either for this or for another reason, the whole thing (10bit HEVC decoding) worked on Windows only, not on Linux
• But QuickSync/libMFX still reports 10bit support on both, Windows and Linux, which is wrong in the latter case

We never fixed the detection because it was reported only once or twice when SkyLake had been pretty old already.