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Re: 626 Plex performance

NASguru
Apprentice

626 Plex performance

Can anyone answer how well the 626 performs for Plex streaming?  For example:

 

1. How many concurent 1080P streams can it transcode?

2. How many concurent 4K steams can it transcode?

 

That said, I noticed the newer versions of Plex/client now can simply copy over the H.262 video from MKV files without transcoding.  While this is a good thing I'm still interested in how many it can transcode at the same time.   

 

Thanks!

 

 

Model: RN716X|ReadyNAS 716X Chassis
Message 1 of 22
StephenB
Guru

Re: 626 Plex performance

It would be useful to get more data on this. It might help if plex could provide some metrics on the compute loads used by their encoders and decoders (ideally for various image sizes).


@NASguru wrote:

 

 the newer versions of Plex/client now can simply copy over the H.262 video from MKV files without transcoding. 

 

 


Just wanted to add that H.262 is more commonly known as MPEG-2 (used in DVDs and US over-the-air broadcast).

Message 2 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

It would be useful to get more data on this. It might help if plex could provide some metrics on the compute loads used by their encoders and decoders (ideally for various image sizes).


@NASguru wrote:

 

 the newer versions of Plex/client now can simply copy over the H.262 video from MKV files without transcoding. 

 

 


Just wanted to add that H.262 is more commonly known as MPEG-2 (used in DVDs and US over-the-air broadcast).


 

Sorry, I should have said H.264 is just streamed directly while H.262 is transcoded.  I should also mention that VC1 used on some HD DVDs is also transcoded.  

 

Message 3 of 22
StephenB
Guru

Re: 626 Plex performance

In general you need to transcode for tthree reasons:

 

(a) the receiver doesn't support the codec

(b) the receiver can't handle the image size

(c) the network can't deliever the bitrate.

 

Ideally the server would always transcode in these cases, and never transcode if that isn't necessary.

 

 

Message 4 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

In general you need to transcode for tthree reasons:

 

(a) the receiver doesn't support the codec

(b) the receiver can't handle the image size

(c) the network can't deliever the bitrate.

 

Ideally the server would always transcode in these cases, and never transcode if that isn't necessary.

 

 


 

Agreed, and specifically for me it's due to the first option 'a'.  I could get around it all if I wanted to re-encode my entire library and all videos moving forward but who has time for that.  Smiley Surprised All my TVs/Rokus are 1080P capable and set that way.  My entire house is wired for Gigbit with RJ-45 drops (some have multiple drops) in every room so that's never been the issue.  Too bad we can't get to a standard we all agree upon so transcoding would be a complete thing of the past.  

 

 

Message 5 of 22
StephenB
Guru

Re: 626 Plex performance


@NASguru wrote:

Too bad we can't get to a standard we all agree upon so transcoding would be a complete thing of the past.  

 

Since video takes about half the global internet bandwidth, there is a big incentive to lower bitrates. MPEG-2 takes 2x the bitrate of H.264 to get the same quality (and H.264 takes about 2x the bitrate of H.265/HEVC).

 

Codec royalties are another challenge (particularly with HEVC).  There's a number of efforts to develop qualtity codecs that are royalty-free.  So I think this fragmentation will get worse before it gets better.

Message 6 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

@NASguru wrote:

Too bad we can't get to a standard we all agree upon so transcoding would be a complete thing of the past.  

 

Since video takes about half the global internet bandwidth,


 

 

I remeber hearing that before Netflix, Vudu, Hulu, Amazon Prime, YouTube and others existed.  Arguably, it was adult content back then that was to blame.   

 

 

Message 7 of 22
StephenB
Guru

Re: 626 Plex performance

Netflix, YouTube, and perhaps Amazon.

 

https://arc.applause.com/2016/06/23/how-much-data-doe-streaming-video-take-up/ says about 70% of US peak-hour bandwidth is video streaming. 

Message 8 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

Netflix, YouTube, and perhaps Amazon.

 

https://arc.applause.com/2016/06/23/how-much-data-doe-streaming-video-take-up/ says about 70% of US peak-hour bandwidth is video streaming. 


 

It's crazy when you think about it.  

Message 9 of 22
NASguru
Apprentice

Re: 626 Plex performance

FYI, I received my RN626X the other day and have already installed Plex.  I was able to transcode 3 seperate 1080P movies using it as my server.  I let all three streams run for over 20 minutes, skipped around on each of them and still witness no buffering issues.  I suspect it can do more but I don't have enough devices to test the theory.  See screen shot below: 

 

transcode.jpg

Message 10 of 22
mdgm-ntgr
NETGEAR Employee Retired

Re: 626 Plex performance

Nice. Yes, it is very powerful. It's amazing how much it can do.

Message 11 of 22
StephenB
Guru

Re: 626 Plex performance

Can you check out 4K->1080p transcoding?  There are some samples here: http://4ksamples.com/

 

HEVC will likely take more CPU than the AVC encodings, so maybe try some of each.

 

You can enable SSH and run TOP while its streaming if you want info on CPU load.  Unfortunately the performance tab doesn't include CPU graphs.

Message 12 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

Can you check out 4K->1080p transcoding?  There are some samples here: http://4ksamples.com/

 

HEVC will likely take more CPU than the AVC encodings, so maybe try some of each.

 

You can enable SSH and run TOP while its streaming if you want info on CPU load.  Unfortunately the performance tab doesn't include CPU graphs.


 

No problem, can I filter the TOP command to only list CPU load that isn't zero?  

Message 13 of 22
StephenB
Guru

Re: 626 Plex performance


@NASguru wrote:

No problem, can I filter the TOP command to only list CPU load that isn't zero?  


I just let it run, the high-percentage CPU processes are at the top.

 

The max isn't 100%, each core counts as 100%.

Message 14 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

@NASguru wrote:

No problem, can I filter the TOP command to only list CPU load that isn't zero?  


I just let it run, the high-percentage CPU processes are at the top.

 

The max isn't 100%, each core counts as 100%.


 

Good information and as a comparison here is what TOP shows for three concurrent 1080P MKV movies being transcoded.  I should mention that bringing up the third movie does take a few seconds longer so the 626 is starting to slow down by then.  

 

tops-results.JPG

 

 Ok, I tested one 4K video and it took about 30 seconds to load but it played fine the first time through.  The 2nd time it buffered for a second and then resumed.   Screen shots below.

 

4K-test-one.JPG

 

tops-ses-astra-uhd-test1-2160P-uhdtv-hevc.JPG

 

2nd HD video didn't have any sound but loaded and played fine 2 times through.  Screen shots are below.

 

4K-test-two.JPG

 

tops2.JPG

Message 15 of 22
NASguru
Apprentice

Re: 626 Plex performance

And here is the last one, which was the Elysium 4K sample.  This one would play almost to the end but then repeatedly buffered at the same spot.  That said, I doubt the 626 could transcode two 4K MKVs concurrently.  Although, the audio was in 7.1 for this 4K sample so it may play smoother if it was 5.1 instead?

 

tops3.JPG

 

tops3.JPG

Message 16 of 22
StephenB
Guru

Re: 626 Plex performance

Thx for checking.

 

The Elysium sample is at a much higher bitrate than the astra ones, and that might be part of the problem.  The original audio is 8 channel DTS-MA (lossless) with a 6 channel DTS lossy "core" and that is clearly being transcoded too.  If you pumped the Roku output through an A/V receiver you might avoid the audio transcode.

 

Anyway, it looks like it does work, but there might need to be some off-line transcoding of some files to a suitable 4K bitrate and perhaps converting the audio to something the player can handle.

 

And of course the 626X CPU is pretty much maxed out on all these clips.

Message 17 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

Thx for checking.

 

The Elysium sample is at a much higher bitrate than the astra ones, and that might be part of the problem.  The original audio is 8 channel DTS-MA (lossless) with a 6 channel DTS lossy "core" and that is clearly being transcoded too.  If you pumped the Roku output through an A/V receiver you might avoid the audio transcode.

 

Anyway, it looks like it does work, but there might need to be some off-line transcoding of some files to a suitable 4K bitrate and perhaps converting the audio to something the player can handle.

 

And of course the 626X CPU is pretty much maxed out on all these clips.


 

No problem and yeah the bit rate for the Elysium clip is 53.6 Mbps compared to less than 20 Mbps for the other two.  I've had plenty of 1080P movies though that had bitrates in the 30 Mbps range that played with no issue but of course there is more to it than just that piece.  I don't have a reciever capable of decoding 7 or 8 channel audio so it wouldnt' have helped much.  I've actually been happy with my older 5.1 DD/DTS receiver but may eventually upgrade it.  I also have one 4K TV and I believe the Roku 4 supports 4K so that would be an option (depending on codec of course) rather than having to transcode the video.  In fact, my 4K TV can play those files directly via DLNA without any issues which is what I did a lot of time prior to being able to transcode 1080P via Plex.  For now, I'm fairly happy with 1080P video quality, but will admit that it wasn't until I got a 4K TV that I could actually see the difference between DVD and BluRay quality since the 4K TV has to upscale DVD almost 8 times. That much processing really starts to become obvious at that point and why I have now started to convert my DVDs over to 1080P where I can.  I can still live with DVD quality on my 1080P TVs for now.  

 

Anyhow, can you elaborate on how to read the TOP output?  I can clearly see the numbers are up but don't know or understand all the columns/etc.  

Message 18 of 22
StephenB
Guru

Re: 626 Plex performance


@NASguru wrote:

Anyhow, can you elaborate on how to read the TOP output?  I can clearly see the numbers are up but don't know or understand all the columns/etc.  


There's a good descriptoin here: http://tecadmin.net/understanding-linux-top-command-results-uses/#

 

It doesn't explain the load average - there is an explanation here: http://www.howtogeek.com/194642/understanding-the-load-average-on-linux-and-other-unix-like-systems/

 

 

Message 19 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

@NASguru wrote:

Anyhow, can you elaborate on how to read the TOP output?  I can clearly see the numbers are up but don't know or understand all the columns/etc.  


There's a good descriptoin here: http://tecadmin.net/understanding-linux-top-command-results-uses/#

 

It doesn't explain the load average - there is an explanation here: http://www.howtogeek.com/194642/understanding-the-load-average-on-linux-and-other-unix-like-systems/

 

 


 

Got it and so looking back the CPU utlization was about 75-80% on a single 4K video.  Two streams would definetly not have worked.  Smiley Sad

 

Message 20 of 22
StephenB
Guru

Re: 626 Plex performance


@NASguru wrote:

Got it and so looking back the CPU utlization was about 75-80% on a single 4K video.  Two streams would definetly not have worked.  Smiley Sad

 


4K transcoding takes a huge amount of CPU, unless you can use GPU acceleration.  So its not surprising that it can't do two.

Message 21 of 22
NASguru
Apprentice

Re: 626 Plex performance


@StephenB wrote:

@NASguru wrote:

Got it and so looking back the CPU utlization was about 75-80% on a single 4K video.  Two streams would definetly not have worked.  Smiley Sad

 


4K transcoding takes a huge amount of CPU, unless you can use GPU acceleration.  So its not surprising that it can't do two.


 

No doubt and I hope that Negear will have a NAS more than capable of it by time I'm ready for 4K transcoding.  Or better yet, I won't need to transcode.  One can only hope.  Smiley Tongue

Message 22 of 22
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