CPU for Plex Media Server? (4k transcoding)

[voidshatter]

So I've just started to look into building a home media server for Plex, and I'd like it to be relatively future-proof. Then "4k transcoding" comes in my mind, as I guess 4k may be the standard resolution for the years to come.

I have little experience in this field (as to Plex, video format, encoding, H265 etc). I've decided to do some search online, and it appears that four different people suggest that a Passmark score of around 15,000 is about to be the minimum requirement for transcoding 4k videos without stuttering.



Checking the Passmark ladder (and estimating some unlisted CPUs by simple calculations with errors), I've found the following (relatively "affordable") CPUs to be on my list (assuming no overclocking):

CPU model: Passmark score, price, 4k transcoding capability for Plex Media Server

AMD Epyc 7601: 51,207 (est.), $3139 (not really affordable!), can transcode three 4k streams concurrently
Intel i9-7980XE: 32,618 (est.), $1999, can transcode two 4k streams concurrently
Intel i9-7960X: 31,224 (est.), $1699, can transcode two 4k streams concurrently
Intel i9-7940X: 30,248 (est.), $1399, can transcode two 4k streams concurrently
AMD ThreadRipper 1950X: 26,350, $999, can transcode one 4k stream
Intel i9-7920X: 24,255 (est.), $1189, can transcode one 4k stream
AMD ThreadRipper 1920X: 23,200 (est.), $799, can transcode one 4k stream
Intel i9-7900X: 23,068, $999, can transcode one 4k stream
Intel i7-7820X: 19,159, $600, can transcode one 4k stream
Intel i7-6900K: 17,980, $999, can transcode one 4k stream
AMD ThreadRipper 1900X: 17,211 (est.), $549, can transcode one 4k stream
AMD Ryzen 1800X: 15,419, $419, can transcode one 4k stream
AMD Ryzen 1700X: 14,663, $325, may stutter
Intel i7-8700K: 14,577 (est.), $350, may stutter
Intel i7-8700: 14,452 (est.), $312, may stutter
AMD Ryzen 1700: 13,816, $270, will stutter

It appears that the Ryzen 1800X is the minimum buy, and its 95W TDP is probably the coolest viable option. The price-performance ratios of the AMD CPUs do look more attractive. And an advantage of these AMD CPUs would be the unofficial support of ECC memory modules (yeah, without 3600C16 or 3200C14 there will be a performance hit).

The advantage of the Intel CPUs? ASRock has a mini-ITX motherboard offering four SO-DIMM DDR4 memory slots, presumably supporting 64GB? The Lian-Li Q33/Q34 ITX case will be able to hold a cooler as tall as 180mm, and a 520W fanless PSU from Seasonic. Going for AMD probably means memory capacity will be limited to 32GB for ITX builds for now.

Coffee Lake 8700K, 8700 and Ryzen 1700X, 1700 are not so good choices for this job, as they are just close to the edge of stuttering.

Any thoughts?

 

[voidshatter]

My thoughts are why are you trancoding 4K video on the fly, wherever possible you should be direct steaming.

Why not just use the optimise feature to create a video file that can be played by clients that aren't able to direct stream 4K h265

Hard disc space is much cheaper than a big CPU with all the heat/power/noise that it will end up bringing to the Plex Server.

I just don't like the fact that I have to wait for optimisation first... Sometimes I just want to watch it straight away

 

[voidshatter]

I know nothing about 4k transcoding but Ithink you may have got your numbers wrong

Whenever a score can be found at Passmark's website, I take it with higher priority than the estimated value at cpu-monkey's. There are errors for sure.

 

[voidshatter]

taking a sledgehammer to crack a nut

Perhaps the Ryzen 1800X won't be generating too much heat or noise, since I can use the Thermalright Le Grand Macho RT CPU cooler as a fanless solution, in conjunction with Seasonic's 520W/460W fanless PSU?

95W for 24x7x365 translates to £133 per year at Southern Electric's current tariff inc VAT. I don't think I can be transcoding all year

Intel CPUs may be more problematic as I would need to do delidding, and I can't use a fanless solution.

 

[voidshatter]

If it's just for streaming can you not use GPU acceleration? Not as good quality but much cheaper.

If I want to stream over the local network, not via the output cable of a graphics card, will GPU acceleration work?

 

[voidshatter]

When did Passmark represent transcoding?

As other have said, why would you be transcoding 4K to 4K on the fly? Seems bizarre as it won't be lossless.

Checking http://wayback.archive.org, the following description by Plex has existed since May 2016.

Do you think transcoding 4k to a mobile device or a smaller 1080p TV would be a good enough reason?

 

[voidshatter]

I would say that would work fine! I am a big advocate of utilising older tech for home media server use, I have a fully stacked Xeon system 8 core 16 thread 2.6Ghz (Turbo to 3.3) 16Gb of DDR3 1333Mhz ECC Reg, Intel S2600CO4 motherboard, Intel 4U Pedestal/Rackmount Chassis and a Intel Server 500W PSU. Granted I did get some parts for nothing as they are old tech but even so they make fantastic, stable servers that can be utilised for a variety of home server use and are reasonably cheap.

A single Xeon E5-2670 should score about 12k in Passmark and should stutter for 4k transcoding if what I'm reading is correct. Two of these would bump the TDP to 230W, when compared against the 95W of a single Ryzen 1800X. Do you find the Rackmount Chassis running quiet enough? I'd like it to be put probably under the TV and don't want too much interference lol

The GPU will need to support HEVC/h.265 decoding for 4K however...

Interesting! Any reliable link to get a list of such GPUs?

Why you jump from 1950X to 7601?
there is the 7401 for $1100 and 24 cores. And 7551 for $2100, a 32core cpu

I was kidding when I quoted an AMD Epyc. I don't think I can handle the cooling or electric bill for it yet But you are right, a 7401 should be looked into!

 

[voidshatter]

Not really any solid lists but pretty much all the Nvidia 10 series and AMD 400/500 series can do HEVC decoding.

Thanks! I still remember that when I had a laptop with Core 2 Duo over a decade ago, I had to configure nVidia's proprietary decoder (something called PureVideo?) in order to enable GPU accelerated playback for some 1080p videos with high bit-rates and mitigate the CPU load. However, there were always compatibility issues for certain videos from time to time. Will it be easy enough to configure Plex to utilise such modern GPUs?

 

[voidshatter]

core 2 duo 8600 freenas server works fine with 1080p videos

Core2 Duo E8600 scores 2400 in PassMark, which is just above the recommended requirement of 1080p transcoding by Plex.

You'll need something scoring above 15,000 in PassMark (or even 16,000 as recommended by Plex employee), which means Ryzen 1700, Ryzen 1700X, Coffee Lake 8700 and Coffee Lake 8700K will all stutter for 4k transcoding. Overclocking the Ryzen 1700 may also be an option, though stability would be in question.

As mentioned by ZXSpectrum, older Xeons may serve well. However, electric bills would be another story.

 

[voidshatter]

Looking into similar performance (around the minimum requirement) and similar TDP, Intel's offering is significantly more expensive than AMD's. Anyone can point me to a decent ITX motherboard for Ryzen 1800X, with at least one M.2 slot, as well as (unofficial) support of ECC memory?

 

[voidshatter]

Looking into some benchmarks related to transcoding, I've found that the Ryzen 1800X may not perform as well as it's supposed to be able to. Speculations would be the optimisations of software utilising specific instruction sets. This means the 1800X build may fail for real-time smooth 4k transcoding on certain video codecs with certain transcoders. Any Ryzen users here can confirm how it works with Plex, preferably with tests on various 4k videos? Unless I can see some real-world use cases, I tend to wait until Intel releases their E3-1200 v7 series based on Coffee Lake and see how these will perform.

 

[voidshatter]

I certainly wouldnt trust raw passmark figures to give you a guide

I have just realised this... I've just done some tests on Alpine AL-514 in my current NAS, and it appears that while it transcodes 1080p at almost 100% CPU load, some formats/codecs play smoothly (with transcoding) while some certain formats/codecs would stutter from time to time. It wouldn't be a good idea to purchase something near the mininum requirement only to find it stutters for certain videos, so no the Ryzen 1800X is not a reassuring choice.

I'll wait for Coffee Lake and see whether there's any viable option for fanless passive cooling.

 

[voidshatter]

Mate you only created this thread to rationalise why Ryzen is crap.

I never said that. With Ryzen I can find an ITX motherboard with ECC support and at the same time with an M.2 nvme slot. With Intel I have no idea where to find such a motherboard, let alone the currently ridiculous pricing of Xeon.

I don't know much about handbreak. All I wonder is Plex's transcoder. I'm looking forward to see some real-world scenarios with Plex.

 

[voidshatter]

I can stream two 4k streams and one 1080p and that runs about 85-90% on cpu load.

Wow! Wait, are you saying that a single E3-1225v3 can simultaneously transcode two 4k streams???

Could you help me run a benchmark test if you have time? Download this video, add it to Plex library, start a stop-watch, optimize it for "Mobile", and record how many seconds or minutes it takes to complete the optimisation. Thanks

 

[voidshatter]

I'm getting more and more confused now. If you can transcode one 4k stream fine with a CPU scoring less than 8k PassMark, then maybe something like Intel Quick Sync has come into play?

If I was to pick a Ryzen for this transcoding task, what would be AMD's equivalence? Will it also get full support in Plex Media Server?

 

[voidshatter]

Tbh I have no idea. I just know it works fine. Happy to provide any screen shots or tests if needed/wanted

Could you help me run a benchmark test if you have time? Download this video, add it to Plex library, start a stop-watch, optimize it for "Mobile", and record how many seconds or minutes it takes to complete the optimisation. Thanks

 

[voidshatter]

Dedicated decoders are part of IGPs, which AMD's chips don't have, and won't have until Raven Ridge.

Can IGPs be used to accelerate transcoding, if the playback is streamed to a remote device via network, *NOT* output via the IGP?

 

[voidshatter]

Sure.

If this is true, then you just made me think twice before going for Ryzen without IGP... Shameful that I have to delid these Intel chips...

 

[voidshatter]

Have you considered Emby? I had Plex but my FX8350 is starting to struggle with some things. I switched to Emby (side-by-side at first, to test) and it has OOTB hardware acceleration for VC1, HEVC, H264, MP4 etc etc. You can use IGP, Nvidia/Cuda or VAAPI/VDPAU. I can now stream without issues and my 1050ti doesn't break much of a sweat. Sorted (for now). It may be worth you considering in place of Plex if resources are an issue.

Are you suggesting that with Emby, I can easily transcode and stream 4k videos to my iOS device, if I have a spare graphics card such like the GTX 980?

 

[voidshatter]

Emby supports hardware encoding OOTB, yes, so you can use the transcoding capabilities of your graphics/IGP hardware. For example, this one's mine:

As you can see it detects the transcoding abilities of my system (in this case just a Pascal 1050Ti, purchased because it supports HEVC/x265 10 bit transcoding). Works perfectly on everything I've thrown at it so far. The drop down box has options for Nvidia, Intel QuickSync, OpenMAX (OMX) and VA-API. I have an Nvidia card and no Intel CPU, so I chose Nvidia.

Great! Where do I find a compatibility list for nVidia cards? Curious to know whether my spare GTX980 can do VP9 and VP9 10-bit or not.

Edit: Just checked the Wikipedia link and it looks like there is no luck for my spare GTX980... It has to be my GTX1080 instead then..

Nowadays Youtube widely uses VP9 and is rumoured to end H264 soon..