Plex Server on Synology DS920+ doesn't transcode 4k to 1080p without buffering

Plex Media Server NAS & Devices
1

Hi I’ve spent hours searching the web and reading the forums and this is such a wide spread issue transcoding buffering I think if I ask for some help it might be quicker.

New to Plex (been using for 6 months) new to this forum so apologies if information not quite right.

Firstly upgraded to latest Synology DSM 7 release and also latest Plex release.

Server Version#: 1.28.2.6151-7000
Synology Server DS920+
Player Samsung TV Plex App 2.013

Problem: I have a synologyDS920+ with Plex Server playing 4k content to a 1080p TV. It constantly buffers when transcoding and therefore at the moment I cannot watch any of my 4k content.

Things I have tried;

  1. Predominantly HW acceleration was enabled, 4k to 1080p buffers 4k to 1080p, and also TrueHD7.1 to AC3. This buffers alot - dashboard shows 4k to 1080p and TrueHD to AC3 , bandwidth about 8Mbps , CPU is only at 60% so why can’t it hardware transcode successful?

  2. I triedHW acceleration off - and confirmed SW transcoding on the dashboard. Slightly better playing of content but still buffering, slightly less . Bandwidth was 8Mbps ok, but CPU about 100% for Plex Server and Synology NAS. Would seem CPU wont cut it for SW Transcoding.

  3. Tried adding VaapiDriver=“i965” Again a slight improvement in reducing the buffering but not really a positive solution. Tried both HW and SW transcoding.

Please can someone point me to a resolution?

Bit frustrated with my Plex experience as I feel HW transcoding at 60% should sort the 4k to 1080p out.

Also the DS920+ wasnt cheap and therefore expected it to deliver in the total package here.

My fear is having to get a 4k TV which may (??) fix my issues but trying to avoid for the meantime if I can.

Can Someone please advise from Plex or Synology?

2

You won’t find anyone from Synology here.

As for Plex, I can help with that.

My first question, which has the single largest impact on a Synology:

  • Do you have subtitles involved
    – Either PGS subtitles in the video which must be burned into the image
    – Are any of the players set to “Always Burn” or are they set to “Automatic” (default)?

Second:

  • Do you have HDR tone mapping enabled ?
3

Hi thanks for your assistance. My reference to Synology was the other users here with Synology NAS and contributing their experience/ resolutions.

  • Subtitles I dont use - Subtitles are never enabled for playing- and so I hope that answers the question sufficiently.
    Is it a problem if the movie came with subtitle capability?

  • Plex Web Player - Burn Subtitles is set to Automatic.

  • HDR Tone Mapping is set to yes

There’s so many settings within Plex it sure would be good to get an assessment , is there a way to dump out a config and have you take a look?

rgs

4

HDR Tone Mapping absolutely destroys any chance for me transcoding movies on my DS920+ without major buffering. I turn off that feature, keep 1080p copies of movies I care a lot about, and just deal with the bad coloring and such for the others. But I also very rarely transcode.

I do have an open ticket with Synology to see how to properly install ocl-icd-libopencl1 and beignet-opencl-icd to get hardware-based tone mapping (based on Plex’s HDR to SDR Tone Mapping support article), but no response yet, and not sure if they can provide that answer.

5

hdr tone mapping don’t work on the syno with the standard package. if you want to use it, you need to follow this guide. its very easy. assuming you have docker installed, just running the script (2nd option in the how to) is the easiest in my opinion.

6

@smann and all.

For the moment , emphasis on MOMENT, please turn off Tone Mapping.

Use the Docker overlay which ‘DJFriday12.5’ :rofl: shared above if you really need it now.

@djfriday13

Which Syno model do you have ?

7

TO ALL FOLLOWING HERE:

Docker PMS is no longer needed for Hardware HDR tone mapping

2 Likes
9

thanks for sharing. This is such a wide spread issue im surprised there is not more resolution/ blogs on the web. Really just want this stuff to work aka Apple UI.

10

@darenf7

Did you read my post?

You don’t need to install ICR on Synology.

  1. They’ll laugh at you.
  2. PMS 1.29.1 (released earlier today – and why I couldn’t tell anyone until now) contains the runtime drivers needed for hardware tone mapping.
1 Like
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Hi @ChuckPa just catching up with the developments as its early morning in the southern hemisphere :slight_smile:

Please what is ICR ?
Sorry mate dont specialise in this space but just seeking to be a user of working products.

Great so is my understanding correct that 1.29 will resolve all my transcoding issues?

I will be able to hw transcode 4k to 1080p with HDR Tone mapping on and receive a proper viewing experience?

Thanks for the support - once I posted here great response/ support.

12

ICR, short for Intel Compute Runtime, are the software runtime libraries which provide hardware tone mapping support when transcoding.

Until now, We’ve resorted to using Docker on our NAS machines because the needed runtime libraries weren’t available, now they are.

We don’t need “Docker Plex” on our NAS boxes anymore.

Being specific .

  1. PMS 1.29.1.6260-420892357 (the current PlexPass beta as I write this)

  2. No subtitle burning. (we all know how fatal that is on any Synology)

  3. Source file is HEVC HDR10 Profile 7 (normal disc rips). Profile 5 is not supportable.

  4. HDR tone mapping button checked in Settings - Server - Transcoder

  5. On a J3455 and above Intel CPU,

  6. Yes, you will have a successful hardware transcoding and tone mapping experience.

13

Hi @ChuckPa thanks for clarifications.

I see 1.29.0.6244 notified on Plex as a released release, does this have the HDR Tone mapping?
I didn’t see it mentioned in the release notes?

Do you want me to run that and report back or the beta 1.29.1.6260?
Assume I get this from Plex beta areas somewhere?

rgs

14

@darenf7

No. PMS 1.29.0.6244 contains a fix for PMS 1.29.0 which Engineering wanted to fix before releasing to Public.

You specifically want PMS 1.29.1 to have the hardware tone mapping support.

15

HERO STATUS! Just to be clear, and make sure I’m not misreading. If I install the latest Plex Distro for Synology I get HDR Tone plus with my Plex Pass hardware acceleration all without having to run in Docker. Correct?

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@house_snappynewday_com

Succinctly…

Y E S ! :slight_smile:

(This is why i wanted everyone to keep their PMS in the default location on Synology… aka, use the overlay method. I knew this was coming)

1 Like
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@ChuckPa Christmas just came early for me. Thank you. Stoked to deploy tomorrow evening.

18

:beers:

:popcorn:

ps: Don’t forget to remove the container and image.

19

is profile 5 not supported for docker either? just making sure i’m not losing anything by going back to using the package center distributions. Thanks again. This is exciting news! and i have confirmed it working correctly on my machine.

20

Profile 5 cannot be supported because there is no HDR fallback layer.

IIRC, this was discussed rather extensively by the app teams as well here in the forums.

Nobody wants to watch a Cyan & Green movie – which is what you get when you transcode it.

21

So with the update installed on my DS920+:

  • Transcoding from HDR to SDR went from buffering for a couple minutes and playing for only about 10 seconds before having to buffer again… to buffering for about 20 initial seconds and then playing for 7 minutes straight, at which point I manually ended the test since there were no issues at all. Also this was the first time running the transcoding with the update, which you guys said takes about an extra 5 seconds to load the drivers for the first time.

  • Also, my average CPU usage went from around 38% to 20%, so huge benefit there with almost half.

All in all, this is probably one of my favorite updates you’ve done. And super happy on the timing since the work around is what I was currently looking into lol.