So, I’ve been playing around with transcoding since the HEVC support update. The new update had fixed the issue, as long as the client supports the HEVC format. For example, I still see artefacting on my Chromebook, since the Plex client on here does not support it, so transcoding defaults to h264, which is weird since VLC plays the same files with zero issues.
Re-checked the two files that I knew had issues (same setup as previous - except WS2025 instead of WS2022. Both files had issues replaying on 1440p browser (Edge) & 4K TV via Nvidia Shield (Plex App).
File #1 - 1080p HEVC Main10 - now works (both web and Shield) by just returning the settings back to the original - i.e. “Use hardware acceleration when available” - that’s frustrating…as nothing else has changed?
File #2 - 4K HEVC Main10 HDR - now works after enabling the original settings and the new “Enable HEVC video encoding” option. I say “works” - there are a few noticeable stutters - not the same issue as before (artifacting/pixelation) - this is more like a full frame stutter - like the server doesn’t have enough resources/buffering - which is odd, as there is basically no utilisation when watching the Plex Dash graphs.
I did find this seems to relate - they are discussing “metadata” being the issue. One of the posts caught my eye:
If it is “metadata” related at least that goes some way to explaining why the issue was/is inconsistent for me and I haven’t noticed it more broadly.
I’ll try this suggestion (convert/remove) on the affected files when I get chance to see if that is actually the reason:
I’m sorry to ask, did you have any luck?
So I tried running the affected files through MKVToolnix to bin off any bad tags and there is no change. I also can’t see any “metadata” on either of the files that stand out or are not the same as other files in the collection.
I’m pretty sure it relates to this (or similar) but I’d be surprised this is still a problem as it was fixed a while ago, unless as @Disgustipated mentioned its being caused by a combination of factors, including the legacy FFmpeg.
As it’s limited to a small part of my collection, I’ll just replace the files to solve, not ideal.
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I doubt its file (metadata) related, since the issue only pops up on QSV. This was also probably proven when they released HEVC support, and it fixed the issue if the clients support the new feature. The issue here is, not all clients support HEVC, so some streams look horrible, some look good. Personally, I had to disable new encoding, since my older clients just get pixelated mess of a video. Hopefully, they will also show some love to the x264 encoder.
Provided a new update status in the original post to recap where we are.
Update 5: This thread has been referenced a few times, and a lot of testing has been completed to get to where we are now. To summarize, there is an issue with Plex and hardware transcoding HEVC / x265 content with Intel Quick Sync on 11th - 13th gen Intel CPUs that utilize Intel Iris XE iGPUs (14th gen status unknown). Hardware transcoding via QS produces frequent blocky frames and artifacts which can be seen in the screenshot below, and in many of the sample clips throughout this thread. Personally, I downgraded to a 10th generation intel NUC and the issues have stopped. I can freely migrate my Plex LXC container between my two Proxmox hosts (10th gen NUC, 12th gen NUC) to confidently reproduce and resolve this issue. Plex support have acknowledged this as a problem but have not replied in 6~ months.
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I will just add my comments here
I’m facing this issue with a Ugreen DXP4800PLUS with it’s Pentium Gold 8505 12th gen cpu.
There is however also a secondary issue that is very similar this one where mostly anime with ass subtitles report a bitrate of 2147483.6 and samsungs tizen does not like this at all causing frequent artifacting every few seconds but checking “Disable Bitrate Limiting” on the tizen client fixes that part of the problem and you are down to the less frequent and less severe issue related to the intel cpus.
I hope this helps anyone coming across this thread who are affected by both issues.
Just to add:
Version 1.41.5.9522 working?
I’ve since migrated to Unraid (Plex official docker container) from WS2025 > no more issues, same hardware (i5-12400/UHD730), with previous all options selected.
My testing with this issue has been limited to CPUs that utilize Intel Iris XE iGPUs, not the UHD. I will try migrating Plex back to my 12th gen NUC and report back.
Update~ This is not fixed. The issue still persists with Intel Iris XE iGPUs.
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I have come to check in once again to complain about this issue. It still appears on every thing that needs transcoding. The HVEC encoder works fine, but the old x264 still pixelates everything.
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When using PGS subtitle burning, such ghosting often occurs in 1080P videos. Please fix it
Adding to the pile, same problem here on an N100 with Unbuntu 24.04 LTS: Macro blocs/artifacts appears while using QSV to transcode.
This seems to impact I frames or badly encoded B frames from the behavior (lasts 1-2secs then resolved)
H265 output isn’t impacted, only H264.
Not sure what FFmpeg version Plex uses, but it could be linked to that, especially with version 7.1 that is quite unstable.
Bro they are using FFMPEG 4 still lol
Dang… time to update then!
Can any Plex employee confirm if there is any work being done on these issues?
@ChuckPa @chrisallen
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This still hasn’t been addressed?? Incredible. Luckily things have been fine with the arc a380 so far… I am considering buying a new mini-pc that has the arc igpu rather than Xe or uhd, has anyone tried that yet? Ultra 5 125H for example…
Transcoder upgrade preview is up: Transcoder Upgrade Forum Preview
Haven’t tested with anything yet, but hopefully it makes a difference for this!
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After testing, it’s still the same
Having these artifacts for about a year now, I would recommend staying the hell away from Plex if you want to use QSV. None of the employees respond here anymore either, so it’s just an echo chamber of pain.
Best chance to get developer review would be to try the transcoder upgrade forum preview and provide logs, otherwise it will just get released and fall to the bottom of priorities.
