I run my Plex in docker. I was able to setup hardware transcoding using my NVIDIA card. When I start a 4K movie in the browser I can see the new process in the nvidia-smi and the CPU load is low.
However if I start the same movie from my LG TV. I still can see a new process in the nvidia-smi. But I also see the Plex-Transcoder process eating the whole CPU and the movie is stopped every 5 seconds for buffering (just like without hardware transcoding). What can cause this difference? What should I try to config?
I am quite lost and that was the only thing I bought Plex Pass so I can transcode 4K movies on GPU.
If someone could give me tips what should I try or check, I would be very grateful.
Thanks!
Why is the video transcoding? Ideally, when playing a 4K movie on a 4K TV, it direct plays or direct streams.
You can monitor playback via Plex Dashboard → Now Playing + Expanded View? It will show if the video or audio is transcoding.
Subtitles on? If so, turn them off.
The Plex LG app has limitations when it comes to subtitles.
If the media is direct streaming, such as when audio is transcoding, enabling any form of subtitle results in a video transcode.
It also results in subtitle burning, when entails adding the subtitles to the video frame instead of sending them as an individual track.
Subtitle burning currently uses the CPU, not the GPU. It is also single threaded, unable to take advantage of multi-core processors. If the CPU cannot process the subtitles in real time, you will experience buffering.
Hi,
thanks for the swift reply. I had the time to do some experiment now and you were right.
When I use no subtitle, the dashboard shows ‘direct stream’ and there were no buffering. Turning off the subtitles, unfortunately, is not an option for us as we are not native speakers.
One thing made me think. When I use the web player, it also transcodes the movie (with or without subtitles) and my Plex server uses the GPU, not use the CPU and the movie is smooth with no buffering. However if I play it from the the the GPU and also the CPU is used on the Plex server and constant buffering stops the movie.
Why is there a difference on the server? Is this effect caused by the different clients? Is it a bug in the LG Plex client or this is an expected behavior for some reason?
What you are seeing is expected. Burning subtitles is a limitation of the Plex LG client.
The best option is to use a device that does not require subtitle burning.
Android TV devices (Nvidia Shield Pro, Amazon FireStick, etc) have much better subtitle support. They do not require subtitle burning when the video or audio is transcoding.
Other Plex clients, such as an AppleTV, may work as well.
Just on more question, I am curious, why is this connected to the Plex client.
I see the CPU load on the Plex server side. Even if the TV (client) needs transcoding the video and burn the subtitle, it could be done on GPU on the server, am I right?
So for me, it seem as a lack of feature in the Plex server, to be able to burn the subtitle on the GPU and not on the CPU.
Plex is working on it. Possibly a forum preview (pre-beta) this calendar quarter. Nothing yet regarding system requirements, supported GPUs, supported operating systems, etc. (which is SOP for Plex).
