So after playing around with a bunch of 4K transcoding it seems that plex uses only the cpu for the decoding of 4K h.265 and then uses the gpu for encoding? Testing two streams I can get a 4K h.265 17mb movie down to 1080 by 8mb with a Ryzen 5900x and 3080ti. CPU usage is around 60 percent and gpu is around 15 percent. Is plex working on being able to use NVDEC?
plex has been using nvdec/nvenc for about a year or more now.
you may want to start @ Plex, 4k, transcoding, and you and follow the various links provided there, all the answers to the questions you should be asking are there.
Is there a way to verify if plex is actually using decode for the GPU? I get the exact same GPU usage with a 1080ti and 980ti both of which cannot decode h265. It just seems like plex is not optimized for any kind of gpu transcoding.
Well, if your CPU is of a certain model (i5,i7, etc) it likely has an on-chip graphics processor that Plex uses for HW re/decoding instead of your Nvidia GPU.
See: Intel Quick Sync Video - Wikipedia
That article has a chart that mentions whether the CPU is capable of encoding as well, or just decoding. Where does your CPU sit under?
This is for AMD. No quicksync. Nvidia GPU. I’ve created a bunch of different plex servers with multiple hardware variations, 980ti, 1080ti, 3060ti and 3080ti. All have very similar results, gpu utilization is 10 percent with 2 transcodes and 1 buffers with cpu usage over 60 percent plus. I understand cpu usage during transcode is going to be high due to also having to transcode audio and also read/write file data but even when you hand break a video you can get 60 to 80 percent gpu utilization. 3080ti can hand break an 80 mb sec 4K video down to 20 mb sec 4K video in about 20 - 30 minutes. Average frame rate of 350fps.
Right now the current setup is Ryzen 3700x with 3060ti. 2 transcodes of 4K 27mb and 19mb to 1080 8mb 1 stream plays and 1 buffers. 10 percent GPU is used and cpu is pegged. If this is just a Plex optimization issue I’d be happy knowing as so then it could be addressed if stated. As 1080 format seems to be at an end, I’m sick of hearing don’t transcode as this is not a viable solution with current hardware.
yes. and it is explained in the 4k faq previously linked.
TLDR the simple answer is use Plex Web > settings > dashboard, and if it shows (hw) next to decode and/or encode, then gpu is being used by plex.
nvidia hardware transcoding should work fine with amd cpus.
if you are under the impression that hardware transcoding shows a lot of gpu load, then you are mistaken. gpu load will be much lower than what cpu only transcoding will do.
cpu is still responsible for all other non video transcoding (ie audio/subtitles) and of course any plex or other processes also running.
I don’t believe 980 supports h265, however 1080/3060/3080 all should be plenty capable. again, the nvidia specs/chart is linked in the 4k faq and is straight from nvidia’s website.
how do you determine what transcoding is used? see the faq about what to look for in the logs/console.
how do you determine why something is transcoding? see the faq about what to look for in the logs/console.
as far as I can tell, you have not indicated what OS, which can also make a difference in gpu transcoding support, and more importantly tone mapping support (and whether or not that happens on the cpu or gpu, depends on the OS).
finally, plex does not currently support ENCODING to 265 at all, with cpu or gpu.
all video transcoding is converted to x264.
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