High CPU Usage When Playing 4K

[boellelis]

Hi community

Currently I am facing the problem that playing 4K videos on plex is causing my CPU to run at 100%.

My Server Setup:
Intel Core i-7 Kabylake 7700
16GB RAM
Ubuntu 16.04

My Client Setup
Apple TV 5th Generation with 4K
Plex App on Apple TV

Playing 1080p(10-20GB) does not affect the CPU usage at all. It shows 2-3% CPU usage. As soon as I start any 4K movie (30GB - 50GB) the cpu usage goes to 99% at all time.

Does anybody know a solution for that?
The plex server software is the newest one (1.9.2).

Thanks in advance

[dreamer81]

Plex does not support 4k (yet) hope full there will be a fix soon.

[boellelis]

Hi dreamer81

Thanks for your post. I guess this cant be true.
See here: https://support.plex.tv/hc/en-us/articles/207339358-Does-Plex-Media-Player-have-support-for-4K-?mobile_site=true

[ChuckPa]

Careful what you call 4K.

You have H.264 versus H.265 (HEVC) encoding as well as 8 bit versus 10 bit (HDR) color

PMS has long since been able to DirectPlay 4K / HEVC provided the television can accept it natively.

If you wish to transcode 4K -> 2K (aka. 1080p), which has 8 bit color, you need an Intel SkyLake class CPU to get HW transcoding. If the CPU is doing the transcoding, expect 90+ CPU utilization to transcode it. per stream

When using PMP, if you’re using an i7-SkyLake class NUC, PMS will DirectPlay to the NUC which will in turn decode/transcode internally however needed. If the NUC does not have the ability to perform the transcoding for the Television, PMS will do it.

Lastly, if you are playing HEVC (h.265) with 10 bit color (HDR) and are transcoding it? You need a KabyLake class CPU (i7-7700 class) because of both the CPU and iGPU. It has nothing to do with Plex. It has everything to do with the complexity of the encoding and data rates

[DudleyNYC]

@ChuckPA said:

Lastly, if you are playing HEVC (h.265) with 10 bit color (HDR) and are transcoding it? You need a KabyLake class CPU (i7-7700 class) because of both the CPU and iGPU.

Why do you say this? My 2012 Mac-mini with an i7-3615QM can do this and still handle two more transcoding sessions without any problem.

[ChuckPa]

@chelseaflyboy

Show me the XML. I have an i7-3740 and an i7-6700. It (the Skylake) can’t transcode HEVC HDR (10 bit color ). The server wants to leap of the rack and strangle me.

[DudleyNYC]

@ChuckPA said:

Show me the XML. I have an i7-3740 and an i7-6700. It (the Skylake) can’t transcode HEVC HDR (10 bit color ). The server wants to leap of the rack and strangle me.

maybe your bitrate is much higher this

[KarlDag]

@ChuckPA said:
@chelseaflyboy

Show me the XML. I have an i7-3740 and an i7-6700. It (the Skylake) can’t transcode HEVC HDR (10 bit color ). The server wants to leap of the rack and strangle me.

I can confirm that I can transcode a 4k HEVC 10bit file in software on my i5-7500. You just need to have enough power, like any other file in Plex.

Of course it will be much easier when HW transcoding arrives.

[ChuckPa]

@KarlDag

Thanks for confirming.

i5-7xxx = 8th generation core. - this is the requirement for HDR
i7-6xxx = 7th generation core - this is the requirement for 4K
i7-5xxx = 6th generation core

Before I get slammed, 5 Mbps of ‘4k’ is NOT ‘4k’.

[KarlDag]

@ChuckPA said:
@KarlDag

Thanks for confirming.

i5-7xxx = 8th generation core. - this is the requirement for HDR
i7-6xxx = 7th generation core - this is the requirement for 4K
i7-5xxx = 6th generation core

Before I get slammed, 5 Mbps of ‘4k’ is NOT ‘4k’.

Could be wrong but I’m pretty sure it makes no difference in software, it’s just raw power. The iGPU has nothing to do with it, YET. (Talking solely about transcoding, not playback).

And yes, 5Mbps 4K is 4K. But you know that already. Resolution, bitrate, yada yada yada.

But my file is 23844kbps HEVC.

[DudleyNYC]

@ChuckPA said:

i5-7xxx = 8th generation core. - this is the requirement for HDR
i7-6xxx = 7th generation core - this is the requirement for 4K
i7-5xxx = 6th generation core

Before I get slammed, 5 Mbps of ‘4k’ is NOT ‘4k’.

Are you basing this off the capabilities of the integrated GPU or do you have some benchmark? The file I posted was 15 Mbps. What bitrate do you suggest is “real” 4k for HEVC?

[ChuckPa]

I am using the published standard plus Intel’s specifications & published performance benchmarks .

UHD: (3840 x 2160p)

The specification allows for three disc capacities, each with their own data rate: 50 GB with 82 Mbit/s, 66 GB with 108 Mbit/s, and 100 GB with 128 Mbit/s. Ultra HD Blu-ray technology was licensed in mid 2015, and players had an expected release date of Christmas 2015.

4K is so loosely defined the best number I can give you is 35-45 Mbps 8 bit color encoding (wikipedia). Basing it on the the UHD spec, with 82 Mbps as the lowest for UHD, reducing 10 bit to 8 bit (storage), you end up with ~50 Mbps for full, authentic 4K If it has 10 bit color, it is UHD and must adhere to the defined spec above.

Any bitrate below 30 Mbps (being generous), while it may be 3840x2160p, isn’t “4K” It’s just a “2160p” video. Nothing fancier can be claimed.

“4K capable” is about encoding, not decoding. Therefore, to test the ability of the machine to transcode in real time, Rip a disk or start with a 3840x2160 video file with a bit rate higher than 20 Mbps (the ideal test would be 50-75 Mbps). Set the bit rate manually to its maximum of 20 Mbps, the 4.0 profile, and the video frame to 1920x1080p in HandBrake, single pass video encoding, H.264 output, audio pass through at no less than 24 FPS . IF it can do that in real-time , without using hardware assist of the GPU, then it’s capable of 4K.

I’ll take the time to do the long hand math if needed but hope this makes sense?

you can start the math yourself. 3840x2160 = 8,294,400 pixels per sec @ 3 bytes per pixel => 24.883 MB per frame (raster) image (what must actually be encoded). Multiply that by 24 Frames/sec and you get 597.196 MB/sec of raster image processing.

Now look at HandBrake’s ‘profiles’. Look at the bit rates for 4.0, 4.1,… 5.0 and then look at ‘Main 10’.

[KarlDag]

@ChuckPA said:
I am using the published standard plus Intel’s specifications & published performance benchmarks .

UHD: (3840 x 2160p)

The specification allows for three disc capacities, each with their own data rate: 50 GB with 82 Mbit/s, 66 GB with 108 Mbit/s, and 100 GB with 128 Mbit/s. Ultra HD Blu-ray technology was licensed in mid 2015, and players had an expected release date of Christmas 2015.

4K is so loosely defined the best number I can give you is 35-45 Mbps 8 bit color encoding (wikipedia). Basing it on the the UHD spec, with 82 Mbps as the lowest for UHD, reducing 10 bit to 8 bit (storage), you end up with ~50 Mbps for full, authentic 4K If it has 10 bit color, it is UHD and must adhere to the defined spec above.

Any bitrate below 30 Mbps (being generous), while it may be 3840x2160p, isn’t “4K” It’s just a “2160p” video. Nothing fancier can be claimed.

“4K capable” is about encoding, not decoding. Therefore, to test the ability of the machine to transcode in real time, Rip a disk or start with a 3840x2160 video file with a bit rate higher than 20 Mbps (the ideal test would be 50-75 Mbps). Set the bit rate manually to its maximum of 20 Mbps, the 4.0 profile, and the video frame to 1920x1080p in HandBrake, single pass video encoding, H.264 output, audio pass through at no less than 24 FPS . IF it can do that in real-time , without using hardware assist of the GPU, then it’s capable of 4K.

I’ll take the time to do the long hand math if needed but hope this makes sense?

you can start the math yourself. 3840x2160 = 8,294,400 pixels per sec @ 3 bytes per pixel => 24.883 MB per frame (raster) image (what must actually be encoded). Multiply that by 24 Frames/sec and you get 597.196 MB/sec of raster image processing.

Now look at HandBrake’s ‘profiles’. Look at the bit rates for 4.0, 4.1,… 5.0 and then look at ‘Main 10’.

Agree to disagree, I guess. What you’ve defined is the UHD standard for 4K Blu-Rays. 4K refers to a resolution of 3840 × 2160 , nothing else. Netflix streams 4K HDR at around 15000kbps, for example. Is it compressed? Sure. Is it 4K? Yes.

Just like if you told me that a 2160p file with 50000kbps and HDR 10 wasn’t “4K” because it was encoded in h264 and the spec calls for HEVC (and VC1?). Doesn’t change a think, it’s 4K because the resolution is 2160p.

[ChuckPa]

Did I not say?

4K is so loosely defined the best number I can give you is 35-45 Mbps 8 bit color encoding (wikipedia). Basing it on the the UHD spec, with 82 Mbps as the lowest for UHD, reducing 10 bit to 8 bit (storage), you end up with ~50 Mbps for full, authentic 4K If it has 10 bit color, it is UHD and must adhere to the defined spec above.

My point is that claiming a machine is ‘4k capable’ is nearly impossible because of the damn loose standard. That said, let’s apply a practical number. Something realistic we’d actually want to watch.

As for Netflix, look at their protocol… They use DASH protocol and fluctuate the bitrate as they need. Therefore we can’t use it… If the bit rate peaks at 100+ Mbps, then yes it’s 4K HDR.

I will indeed agree to disagree because it looks like you’re mixing apples and oranges. H.264 8-bit vs HEVC 10-bit

[ChuckPa]

I would like to add, @Achilles knows video FAR better than I. He can fill in what we’re both missing.

[DudleyNYC]

I guess I just take a much more practical view where 4K televisions are 2160p and therefore 4K is something people find of an acceptable quality that plays at 2160p. I probably have lower standards for what is acceptable but then I’m not ripping 4k blu-rays.

Still, my real-world experience seems to contradict your claims about necessary processors. While I’m not sure I have anything handy that is 50Mbps, I do have a 4K10-bit HEVC film at 36Mbps (42GB total file size) which I believe meets your definition of 4K and is also along the lines of the types of files the OP is having problems with (all he said was 4K movies 30-50GB in size). My Mac-Mini with the i7-3615QM has absolutely no trouble playing this file at 20Mbps 1080p. In fact it can still transcode a live TV stream (MPEG2 to h264) while transcoding the film.

Can it pass your handbrake test? No. But I don’t see how it makes sense, in the context of Plex playback, to define whether a machine is 4k capable based upon encoding something in Handbrake. Plex’s ability to play 4K content should be defined by Plex’s ability to play 4K content (irrespective of your definition of 4K.) So in the world of academic discussions perhaps an i7-6xxx is necessary for 4k but in the world of watching films on Plex, I’d suggest you can get by with less.

[KarlDag]

@chelseaflyboy said:
I guess I just take a much more practical view where 4K televisions are 2160p and therefore 4K is something people find of an acceptable quality that plays at 2160p. I probably have lower standards for what is acceptable but then I’m not ripping 4k blu-rays.

Still, my real-world experience seems to contradict your claims about necessary processors. While I’m not sure I have anything handy that is 50Mbps, I do have a 4K10-bit HEVC film at 36Mbps (42GB total file size) which I believe meets your definition of 4K and is also along the lines of the types of files the OP is having problems with (all he said was 4K movies 30-50GB in size). My Mac-Mini with the i7-3615QM has absolutely no trouble playing this file at 20Mbps 1080p. In fact it can still transcode a live TV stream (MPEG2 to h264) while transcoding the film.

Can it pass your handbrake test? No. But I don’t see how it makes sense, in the context of Plex playback, to define whether a machine is 4k capable based upon encoding something in Handbrake. Plex’s ability to play 4K content should be defined by Plex’s ability to play 4K content (irrespective of your definition of 4K.) So in the world of academic discussions perhaps an i7-6xxx is necessary for 4k but in the world of watching films on Plex, I’d suggest you can get by with less.

The thing is, Plex on-the-fly transcoding uses far lower h264 standards compared to his handbrake test, so much easier on the system.

[ChuckPa]

Plex uses , at most, the 4.0 profile (20 Mbps). That’s why I referenced it.

[osalcido]

Agree to disagree, I guess. What you’ve defined is the UHD standard for 4K Blu-Rays. 4K refers to a resolution of 3840 × 2160 , nothing else. Netflix streams 4K HDR at around 15000kbps, for example. Is it compressed? Sure. Is it 4K? Yes.

O geez why argue about semantics like this. Its clearly not the quality 4k op is looking for / having trouble with. People here have alot of free time to invent reasons to argue i guess

[KarlDag]

@ChuckPA said:
Plex uses , at most, the 4.0 profile (20 Mbps). That’s why I referenced it.

Plex uses very fast or superfast profile. No way that’s what you use to transcode your files in handbrake.