Server Version#: Version 1.28.1.6104
Player Version#: Roku 7.0.13.7804-2fd4cda44-Plex
Transcoding fails and movie will not start when I try to play a 4k mkv file that does HDR tone mapping and HW transcoding and then enable the subtitles. This is true if the movie is set to start with Subtitles (Forced) or if I try to turn on subtitles to a movie that is already successfully transcoding and playing back. This does not occur on an Nvidia Shield client, and I believe it is due to the fact that the Shield and the Roku treat subtitles differently (COuld be mistaken… I think they are burned in on Roku, but not shield).
As a test, I disabled HW acceleration on transcoding, and the files played a little better - meaning that they started playback successfully but hit buffering (expected due to my system not being able to handle the load). This was still an interesting result, as the CPU transcoding didn’t show the same behavior as HW transcoding (does not start playback at all).
I used 3 movies for this testing and logging, “13 Hours”, “Bram stokers Dracula”, and “Captain America Civil War”. PMS logs are attached.
Thanks for your help. PMS logs.zip (487.4 KB)
as the HW accelerated test cases.
Aug 21, 2022 11:10:54.762 [0x7f1868a22b00] INFO - Plex Media Server v1.28.1.6104-788f82488 - Ubuntu PC x86_64 - build: linux-x86_64 debian - GMT -05:00
Aug 21, 2022 11:10:54.763 [0x7f1868a22b00] INFO - Linux version: 20.04.4 LTS (Focal Fossa), language: en-US
Aug 21, 2022 11:10:54.763 [0x7f1868a22b00] INFO - Processor: 8-core Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz
Aug 21, 2022 11:10:54.763 [0x7f1868a22b00] INFO - Compiler is - Clang 11.0.1 (https://plex.tv 9b997da8e5b47bdb4a9425b3a3b290be393b4b1f)
Aug 21, 2022 11:10:54.763 [0x7f1868a22b00] INFO - /usr/lib/plexmediaserver/Plex Media Server
does not have hardware HEVC or HDR support.
The most it can do is basic H.264
For HW HEVC & HDR you minimally need a KabyLake class (-7xxx) CPU
@ChuckPa The system has an Nviidia 1650 gpu installed. It transcodes and tone maps for the roku clients just fine, so long as no subtitles are turned on…
lspci -k | grep -A 2 -i “VGA”
01:00.0 VGA compatible controller: NVIDIA Corporation Device 1f0a (rev a1)
Subsystem: ASUSTeK Computer Inc. Device 879b
Kernel driver in use: nvidia
In my attached logs there should be an example where transcoding of “13 hours” was running fine until I turned on the subtitles, at which point it craps out.
*When subtitles(Vobsub) are turned off - the roku client “stream info” shows a “speed” in the 10’s and 11’s.
*When subtitles are turned on - the roku client “stream info” shows a “speed” of 1.
Should there be that much of a performance hit turning on the subs?
Same files I listed above, 13 hours, Bram stokers Dracula, Captain America civil war. All 3 were UHD MakeMKV MKV copies, no post processing. I picked on Dracula and Captain America Civil war first, because they have forced subs.
For Captain America CW, The subs are:
Forced true
Codec PGS
Language English
Language Tag en
Display Title English Forced (PGS)
Extended Display Title English Forced (PGS)
But similar to 13 hours, any of my UHD MKV files fail to transcode and play back when I turn on subs. They pretty much choke at 13% and try a couple times, then error out. So I don’t think its a “forced” sub thing. At no time on any of these files does my system indicate CPU, memory, or GPU get maxed… seems like there’s a bottleneck elsewhere.
The Roku is a 4662RW - Roku Ultra LT, it is connected via ethernet.
Thanks again for your help getting this figured out and resolved.
@ChuckPa Know your busy, just checking in to see if there are any updates. Also, did my info above help you recreate what I am seeing? Need any more info?
I’ve been having a similar issue for the past month or so. If I enable subtitles on a movie/show, it buffers to no end, 1080p or otherwise. But it’s only on my PS5/Xbox Series X/LGTV clients. Plays back fine on iPad/Windows with subtitles on. Since this all worked prior to a month ago I’m hoping it isn’t on my end since nothing has changed. Looking forward to trying the update and getting back to subtitle life!
I tracked down this issue aswell. Transcoding HDR-Content and having subtitles on (PGS) is throttling the transcoding to below 1.0 ratio which leads to buffering.
I’ve got an Nvidia GTX 1060 for Transcoding.
Scenario 1: 4K-HDR to 1080p with PGS-Subs → CPU Usage goes up to ~25%, Decode/Encode on the GPU is below 10%, client is buffering
Scenario 2: 4K-HDR to 1080p with PGS-Subs but disabled tone mapping → CPU-Usage below 5%, Decode/Encode on the GPU goes up to 5.0x-8.0x, client plays fine
Scenario 3: 4K-HDR to 1080p with disabled Subs and enabled tone mapping → same behavior as in Scenario 2.
