Which is these CPUs is suitable for Plex encoding?

[King Mustard]

I'm going to buy a small system and make it a Plex server.

I've found various NUCs, SFF systems etc. and they have the CPUs below.

My video files are x264 and x265. Mostly 1080p x265 but soon enough, I'll transition to 4k x265.

Transcoding is often used.

Two clients maximum at any one time (two Chromecasts).

Which of the following do you think will do the job?

 

[ViRGE]

If the software support is there for Intel QuickSync, my vote would be for a Kaby Lake Pentium. This way to have a CPU with full hardware encode and decode support for HEVC, along with VP9 decode support.

 

[LTC8K6]

Celeron 3865U looks good with HD610.

https://ark.intel.com/products/96506/Intel-Celeron-Processor-3965U-2M-Cache-2_20-GHz

 

[coercitiv]

Transcoding is often used.

Two clients maximum at any one time (two Chromecasts).

Which of the following do you think will do the job?

I'm in a similar situation with you, in the sense that I use Plex server with mostly 2 Chromecasts, so I can probably contribute with some info.

My original Plex server machine was a Kabini Athlon 5350 (Passmark score 2579). It was able to encode 1 FHD video stream, but anything above that proved problematic (delayed playback etc). As I was planning to start sharing the server with other family members I transitioned towards a desktop Skylake i5, which can probably handle 3 streams, maybe 4. (in my original tests I only made sure the machine can handle 2 simultaneous streams with very good response time)

When using Chromecasts your server will likely be under near zero load, as these devices will probably handle the media in their original format. Even when you transition to 4K, as long as you also update your Chromecasts to 4k models (or whatever other adequate terminal you choose) you will be ok with little processing power on the Plex server.

Personally I would not aim lower than a Kaby Lake Pentium 4560 or 4560T if you want a low power machine - these are 2c4t models with considerably more processing power than most of the CPUs included in your list.

PS: Plex does not support QuickSync or any hardware encoding tech.

 

[The Stilt]

For X265 you'll definitely need a CPU with AVX2 support (AMD's AVX2 implementation doesn't count). On Haswell and newer Intel designs AVX2 provides > 20% (IPC) performance boost in HEVC encoding.

However all of those CPUs are utterly useless for HEVC encoding to begin with.
My 18C/36T Haswell-EP peaks at < 5fps while encoding Main10 3840x2160P < 30Mbps videos with good settings.

 

[coercitiv]

For X265 you'll definitely need a CPU with AVX2 support (AMD's AVX2 implementation doesn't count). On Haswell and newer Intel designs AVX2 provides > 20% (IPC) performance boost in HEVC encoding.

I don't think hires H265 encoding is a likely scenario, at least not for real time streaming.

Encoding performance is a factor only when the playback device does not support the original media or a bandwidth limitation is in place, hence the server needs to convert with a suitable codec & bitrate. So the likely situation would be real time H265 decode + H264 encode with a suitable bitrate.

It is true though that depending on what usage scenario one sets for a Plex server, computation power requirements may vary exponentially.

 

[Reinvented]

I absolutely love Plex, but I also stream to a Chromecast. My question for you is what exactly are you streaming to that requires your stream to be encoded? The ONLY time something needs to be encoded is when your target doesn't support the format. Or if you use mkv files, or something of the sort where it requires real time encoding of audio and video.

As far as the CPU that can handle it, it's pretty much whatever the fastest clock speed you can get and multiple cores/threads, and of course this is dependent upon what your playback rate is at. Since I mostly stream stuff at home, I just leave it on "Original" and because it's also in native 1080p/blu-ray format.

 

[cfenton]

If you know there will be a lot of transcoding, for whatever reason, then none of those CPUs will be any good. They are all super low power. HEVC in particular still requires a lot of power to encode without hardware support. My Ryzen 1700 with 8 cores and 16 threads can't software encode 1080p HEVC in real time, much less 4K.

 

[Phynaz]

Your problem isn't going to be the encoding, it's your H.265 source getting transcoded to H.264 in real time. That's not going to happen.

Assuming you have a Chromecast Ultra you can hack it to support Directplay of H.265. With this transcoding may not be required (depending upon audio codec, Chromecast doesn't support DTS)
https://forums.plex.tv/discussion/comment/1383957/#Comment_1383957

You should read through here:
https://forums.plex.tv/categories/chromecast

 

[Phynaz]

Guys, he's not going to encode H.265. Plex automatically transcodes the source to a bitstream and container that's supported by the playing device. In most cases that's H.264 in a MP4 container with AAC or MP3 audio.

So what he's looking to do is multiple real-time H.265/DTS to H.264/AAC transcodes. Internally the Plex trancoder uses ffmpeg and various libraries.

As long as the playback device supports it - such as a 4th gen Roku - Plex will stream H.265/AC3 directly, and even a NAS CPU is plenty for that.

 

[cfenton]

Guys, he's not going to encode H.265. Plex automatically transcodes the source to a bitstream and container that's supported by the playing device. In most cases that's H.264 in a MP4 container with AAC or MP3 audio.

So what he's looking to do is multiple real-time H.265/DTS to H.264/AAC transcodes. Internally the Plex trancoder uses ffmpeg and various libraries.

As long as the playback device supports it - such as a 4th gen Roku - Plex will stream H.265/AC3 directly, and even a NAS CPU is plenty for that.

Oops, my mistake. Though, he mentioned he's going to be streaming to a Chromecast. As you say, the CPU would still have to transcode h.265 to h.264, and I don't think any of those CPUs will be able to do that. To me, it would make more sense to get receiving devices that can play h.265 files, or stop encoding with h.265.