Hi - just put together an i7-8700k to be used as a dedicated plex server. Picked the 8700k specifically for it’s quicksync capabilities.
Can any of the devs explain how plex decides to use hardware transcoding? I’m noticing, on the same file, it will sometimes use hardware transcoding (signified by (hw)) and sometimes won’t (no (hw) and 100% CPU usage).
Why is this?
Thanks!
https://support.plex.tv/articles/115002178853-using-hardware-accelerated-streaming/
scroll down to “Compatible formats and limitations”
You might wanna compare the Plex media info of different videos to get an idea what might be the deciding factor.
If you post a few Plex XML info of videos which do work with (hw) transcoding and some which do not, we could give you some hints as well.
It’s the exact same video. Sometimes it uses hardware transcoding, sometimes it doesn’t (all playing from the same client).
Does plex decide based on CPU / GPU load at all?
@nkouts said:
It’s the exact same video. Sometimes it uses hardware transcoding, sometimes it doesn’t (all playing from the same client).Does plex decide based on CPU / GPU load at all?
If there are other transcodes running at the time, it may fall back to software. Depending on whether the GPU returns a ‘not ready’ (because it may be occupied by another transcode.)
It’s most likely a bug. Mine does the same on an i7 8700 - very inconsistent. GPU is not used by anything else during my tests and simply starting, stopping and restarting a video could result in different behavior.
But, even if you get it to hw transcode, don’t get too excited (if you’re on Windows that is). We’re quite some time off form when we will get proper hw transcoding especially for something like HEVC 10 bit 60 fps. I tried both plex and emby and both do a crappy job because ffmpeg does a crappy job at this and they’re both relying on it. It basically stutters and blocks avery 10-20 seconds even though the neither the CPU nor the GPU are maxed out. I get much better (smoother) playback experience when using software transcoding although that means the machine is pretty much unusable for anything else.
@ionianx said:
It’s most likely a bug. Mine does the same on an i7 8700 - very inconsistent. GPU is not used by anything else during my tests and simply starting, stopping and restarting a video could result in different behavior.
But, even if you get it to hw transcode, don’t get too excited (if you’re on Windows that is). We’re quite some time off form when we will get proper hw transcoding especially for something like HEVC 10 bit 60 fps. I tried both plex and emby and both do a crappy job because ffmpeg does a crappy job at this and they’re both relying on it. It basically stutters and blocks avery 10-20 seconds even though the neither the CPU nor the GPU are maxed out. I get much better (smoother) playback experience when using software transcoding although that means the machine is pretty much unusable for anything else.
My i7-8700k with HW transcoding seems to be working great now. No stuttering with HEVC 4K. I do notice it takes a bit longer to load than software transcoding. Not overclocking but the PC is dedicated to plex.
@nkouts said:
My i7-8700k with HW transcoding seems to be working great now. No stuttering with HEVC 4K. I do notice it takes a bit longer to load than software transcoding. Not overclocking but the PC is dedicated to plex.
What did you change since your initial post that it made it work? Did you do any software updates (plex/drivers etc) or settings changes? Also, what OS are you on?
Win 10 pro. Newest intel display drivers. Latest plexpass (beta) version.
Pretty much the same here except the latest plex beta version.
If you have time, could you please do me a favor and download this specific 4k demo file from here and tell me how it works.
It plays but pauses to buffer about every 20 seconds or so. First 4k file I have that causes this on my i7-8700k. I assume because it is 60fps.
@ionianx said:
It’s most likely a bug. Mine does the same on an i7 8700 - very inconsistent. GPU is not used by anything else during my tests and simply starting, stopping and restarting a video could result in different behavior.
But, even if you get it to hw transcode, don’t get too excited (if you’re on Windows that is). We’re quite some time off form when we will get proper hw transcoding especially for something like HEVC 10 bit 60 fps. I tried both plex and emby and both do a crappy job because ffmpeg does a crappy job at this and they’re both relying on it. It basically stutters and blocks avery 10-20 seconds even though the neither the CPU nor the GPU are maxed out. I get much better (smoother) playback experience when using software transcoding although that means the machine is pretty much unusable for anything else.
@ionianx - after much testing I agree with you. Software transcoding seems to be better (faster, better quality) on my i7-8700k - including 4k video. I’ve overclocked my unit and dedicated it to plex for now.
If I knew hardware transcoding wasn’t up to snuff I probably would have built an i9. Oh well.
I’m using the same CPU but when I click on use hardware transcoding my PMS will crash if I play any video on any devices, not sure what the problem is, do you face the same issues?
awesome info , i was planning to build new system for plex and it seems like i9 9900k will be the best cpu for the job
i have 8700k and i am suffering in software and hardware both, sometimes it annoy me because its not using the nvidia gpu nor the built in , i tried to swap in motherboard bios and I get 100% cpu 4K HDR to 1080p ( yes i know some might ask why u do that if there is no tone maping bla bla , it works in IOS and the colors are good not washed out )
so the video never plays , and the cpu stays 100% forever
