Hardware transcoding not working on AMD/Docker

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Server Version#: 1.32.7.7484 (TrueNAS App → Docker image)
Player Version#: iOS 8.25

I have a TrueNAS server, running Plex via the TrueNAS-provided “app”, which is a wrapper around the Plex Docker image at Docker

I have integrated AMD graphics, configured to pass through into the container, correctly detected by the server:

Sep 15, 2023 09:47:24.862 [140540243983160] DEBUG - [GPU] Got device: Cezanne [Radeon Vega Series / Radeon Vega Mobile Series], amd@unknown, default true, best true, ID 1002:1638:1002:1636@0000:30:00.0, DevID [1002:1638:1002:1636], flags 0x30065
Sep 15, 2023 09:47:24.862 [140540243983160] INFO - Preemptively preparing driver rsv for GPU Cezanne [Radeon Vega Series / Radeon Vega Mobile Series]
Sep 15, 2023 09:47:24.862 [140540243983160] DEBUG - [DriverDL/rsv] Skipping download; already exists

However, when it comes to actually using it, VAAPI fails to initialize, due to a symbols issue in the Plex-downloaded radeonsi_drv_video.so:

Sep 15, 2023 11:49:36.451 [140540127030072] DEBUG - [Req#d1d/Transcode] Codecs: testing h264_vaapi (encoder)
Sep 15, 2023 11:49:36.454 [140540127030072] DEBUG - [Req#d1d/Transcode] Codecs: hardware transcoding: testing API vaapi for device '/dev/dri/renderD128' (Cezanne [Radeon Vega Series / Radeon Vega Mobile Series])
Sep 15, 2023 11:49:36.458 [140540127030072] ERROR - [Req#d1d/Transcode] [FFMPEG] - libva: dlopen of /config/Library/Application Support/Plex Media Server/Cache/va-dri-linux-x86_64/radeonsi_drv_video.so failed: Error relocating /config/Library/Application Support/Plex Media Server/Cache/va-dri-linux-x86_64/radeonsi_drv_video.so: _ZTTNSt3__219basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE: symbol not found
Sep 15, 2023 11:49:36.458 [140540127030072] ERROR - [Req#d1d/Transcode] [FFMPEG] - Failed to initialise VAAPI connection: -1 (unknown libva error).
Sep 15, 2023 11:49:36.458 [140540127030072] DEBUG - [Req#d1d/Transcode] Codecs: hardware transcoding: opening hw device failed - probably not supported by this system, error: I/O error
Sep 15, 2023 11:49:36.458 [140540127030072] DEBUG - [Req#d1d/Transcode] Could not create hardware context for h264_vaapi

This matches up with my own experiments - I don’t see any symbol resembling std::__1::basic_istringstream<char, std::__1::char_traits<char>, std::__1::allocator<char> > exported by the libc++.so.2 bundled with Plex (which I assume is some version of LLVM libc++):

$ readelf -Ws --dyn-syms libc++.so.2 | grep istringstream
$

Whereas an appropriate symbol is found on my local desktop’s libc++.so.1:

$ readelf -Ws --dyn-syms /usr/lib/x86_64-linux-gnu/libc++.so.1 | grep istringstream
   632: 00000000000ceabf    70 OBJECT  WEAK   DEFAULT   15 _ZTSNSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE
  1162: 00000000000effa8    24 OBJECT  WEAK   DEFAULT   21 _ZTINSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE
  1334: 00000000000efee8    80 OBJECT  WEAK   DEFAULT   21 _ZTVNSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE
  1611: 00000000000eff58    80 OBJECT  WEAK   DEFAULT   21 _ZTCNSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE0_NS_13basic_istreamIcS2_EE
  1933: 00000000000eff38    32 OBJECT  WEAK   DEFAULT   21 _ZTTNSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEE
  1981: 0000000000068e90   150 FUNC    WEAK   DEFAULT   13 _ZNSt3__119basic_istringstreamIcNS_11char_traitsIcEENS_9allocatorIcEEEaSEOS5_

There’s no .comment section in the radeonsi_drv_video.so binary, but with a cursory examination, it seems to have been built with a radically different version of Clang to libc++ or Plex itself (both of which say Clang 11.0.1)? Perhaps some flavour of 16.0.1, linked against libc++ 16.0.1, but shipped against 11.0.1?

[FordGuy61]

PMS 1.32.6+ HW transcoding issues and corrections

PMS 1.32.6+ HW transcoding issues and corrections. ALL: We’re really sorry. We missing a whopping fault in PMS. Specifically, we missed a change which broke HW tone mapping support on Linux platforms. ( that’s what I get for sleeping from 4am → 6am ) Where we’re at We’ve got the fault isolated down to a few changes which broke things and are now walking through those source code changes line-by-line again. We will get there as this is a “When” problem and not an “I…

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I don’t think it’s a tone mapping problem, it’s not HDR content specific

[FordGuy61]

HW transcoding is also affected.

Plex pulled 1.32.6 & 1.32.7 from distribution.

Suggest you roll back.

Monitor the thread linked above for updates. Scroll to the bottom, change Normal to Watching, to be notified of new posts.

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It looks like an updated driver was pushed out around a week ago, the new radeonsi_drv_video.so is no longer looking for symbols not found in libc++ 11, and HW transcoding is functional.