The file to look at is /tmp/plexinstaller.log. It contains host inventory results.
NOTE:
The client (player) is set for 2Mbps limit. Might want to check that.
Dec 23, 2021 14:46:28.817 [0x7f37f847db38] DEBUG - MDE: Scream (1996): Direct Play is disabled
Dec 23, 2021 14:46:28.817 [0x7f37f847db38] DEBUG - MDE: Scream (1996): no direct play video profile exists for http/mkv/hevc
Dec 23, 2021 14:46:28.817 [0x7f37f847db38] DEBUG - MDE: Scream (1996): no direct play video profile exists for http/mkv/hevc/dca
Dec 23, 2021 14:46:28.817 [0x7f37f847db38] DEBUG - MDE: Scream (1996): no direct play video profile exists for http/mkv/hevc/dca
Dec 23, 2021 14:46:28.817 [0x7f37f847db38] DEBUG - MDE: Scream (1996): no direct play video profile exists for http/mkv/hevc/ac3
Dec 23, 2021 14:46:28.817 [0x7f37f847db38] DEBUG - MDE: Scream (1996): selected media 0 / 20571
Dec 23, 2021 14:46:28.817 [0x7f37f847db38] DEBUG - Streaming Resource: Calculated bandwidth of 85000kbps exceeds bandwidth limit. Changing decision parameters provided by client to fit bandwidth limit of 2000kbps
Dec 23, 2021 14:46:28.817 [0x7f37f847db38] DEBUG - Streaming Resource: Determining preferred transcode encoders through transcode only decision.
Dec 23, 2021 14:46:28.818 [0x7f37f847db38] DEBUG - Scaled up video bitrate to 273681Kbps based on 4.500000x fudge factor.
Dec 23, 2021 14:46:28.818 [0x7f37f847db38] DEBUG - Scaled up video bitrate to 273681Kbps based on 4.500000x fudge factor.
The issue is hardware transcoding. It works correctly when tone mapping is disabled, but enabling tone mapping switches everything to software transcoding. This happens at every client bitrate, except native streaming.
EDIT: Everything worked properly earlier this year. A 4K HDR stream could be transcoded with less than 10% CPU usage. Since updating to 1.25.2.5319, HW transcoding does not work, and a single 4K HDR stream utilizes 60-80% of the CPU. I’ve tried downgrading to previous versions, and HW transcoding still does not work with tone mapping.
Here are logs showing the issue with a 12mbps transcode, 4K HDR → 1080p SDR with tone mapping enabled. I have hardware accelerated transcoding enabled, but the transcoding is still being done in software and it is using 60% of my CPU
No ASS subtitles. The .MKV files retain all the PGS subtitles from the disc rip, but no subtitle tracks were enabled by the client’s stream. Again, everything worked correctly earlier this year with the same .MKV files.
60% CPU for a subtitle burn and audio conversion, on an i5 – a bit higher than I’d expect but not unreasonable.
If you weren’t using the subtitles but the video / audio tracks are “UNK” (unknown) from the rip, the transcoder will start as software and be ready to engage the subtitles
Thanks for the explanation. I appreciate it, especially over the holiday. Is that a change in the Plex coding? Is it something new with the Intel dependencies? Is it specific to tone mapping?
I was able to use HW acceleration with tone mapping on all of my 4K .mkv rips earlier this year on version 1.24, and all of my rips have PGS subs. Unfortunately, rolling back to 1.24 now doesn’t fix the issue. HW acceleration also still works on these files as long as tone mapping isn’t enabled. I’d really prefer not to remux all of my mkvs.
If the requested playback language is available as an audio track – select it
If not, play the first track (which is almost always a UNK track) and play it
ALSO find a subtitle track (if available) and prepare to use it.
It’s ready to engage (display) the subtitles the instant you turn them on
IF the desired audio matched the default track audio – and you want subtitles-- then it would pause and start burning (a noticable delay) as it refills the buffers to the play
This really does come down to ‘media curation’ and making certain the language you’re going to use the most often is either the only language or the default language track AND you don’t drag around any subtitle tracks you don’t need (A VERY common problem I see in countless log files)
I just checked the files in MKVToolNix, and none of the tracks are flagged “UNK”. They all have proper language flags: “en”, “fr”, “de”, “it”, etc. See attached.
Respectfully, this doesn’t sound like a media curation issue. This sounds like a software issue. Plex shouldn’t be preparing to use the subtitles unless they’re enabled by the user. I would much prefer HW accelerated tone mapping over instant subtitle availability. At least, it’s something that should be an option for the user.
I tried the experiment. I removed all of the subtitle tracks and left only one English audio track. Hardware accelerated tone mapping still is not working. So, it’s not a subtitle issue. Logs attached.
Have you considered / tried updating to the latest Intel Compute Runtime drivers provided by Intel at
I did not do any of the development work for this. All I can suggest is making sure the drivers (ICR) are up to date because I don’t see the ‘failed to find device’ error which is known.
It’s going to take Engineering to see what’s really wrong if more than just ICR updating.
