Playback of 4k HDR media stuttering since Plex Pass

[snovvdog]

Server Version#: Version 1.24.5.5173
Player Version#: 5.27.3 (On Samsung 75tu7020)

Hi,

I have bought a Plex Lifetime pass for the hardware Encoding and the HDR tone mapping.

Unfortunately now my server is unable to provide a stutter free experience on playing HDR media:

Media

• Duration 55:22
• Bitrate 14003 kbps
• Width 3840
• Height 2160
• Aspect Ratio 1.78
• Video Resolution 4K
• Container MKV
• Video Frame Rate 24p
• Video Profile main 10

Part

• Duration 55:22

• Size 5.42 GB

• Container MKV

• Video Profile main 10

• Codec HEVC

• Bitrate 11761 kbps

• Language English

• Language Tag en

• D O V I B L Compat I D 6

• D O V I B L Present true

• D O V I Level 6

• D O V I Present true

• D O V I Profile 8

• D O V I R P U Present true

• D O V I Version 1.0

• Bit Depth 10

• Chroma Subsampling 4:2:0

• Coded Height 2160

• Coded Width 3840

• Color Primaries bt2020

• Color Range tv

• Color Space bt2020nc

• Color Trc smpte2084

• Frame Rate 23.976 fps

• Height 2160

• Level 5.1

• Profile main 10

• Ref Frames 1

• Width 3840

• Display Title 4K (HEVC Main 10 HDR)

• Extended Display Title 4K (HEVC Main 10 HDR)

• Codec EAC3

• Channels 6

• Bitrate 1023 kbps

• Language English

• Language Tag en

• Audio Channel Layout 5.1(side)

• Sampling Rate 48000 Hz

• Title EAC3 7.1

• Display Title English (EAC3 5.1)

• Extended Display Title EAC3 7.1 (English 5.1)

• Codec AC3

• Channels 6

• Bitrate 448 kbps

• Language English

• Language Tag en

• Audio Channel Layout 5.1(side)

• Sampling Rate 48000 Hz

Only when I turn off acceleration and hdr tone mapping, it plays smoothly.

I’m using Windows 10, with an i7 8700K at 5ghz, 32gb ram and a Geforce 1080TI.

With software encoding I see my cpu use go to 100%.
With hardware acceleration it only goes up to 60 ish %, with my GPU use hovering around only 5-10%…

Is my hardware insufficient for HDR tone mapping? Would upgrading to an Intel Core i7-9700K help (which I can still do on my platform)?

Also why is the CPU use still so high (~60%) with GPU encoding enabled (which is barely used)?

I see HDR tone mapping is not supported on the gpu on Windows, will this be fixed ?

I feel like upgrading to Plex lifetime pass is giving me more problems than it has solved/improved…

MY TV should decode HDR10 natively, I don’t really understand why it is being transcoded in the first place?

EDIT:
I think I see a problem, the video is being encoded to a way to high bitrate:

My TV only has a slow 100 mbit LAN port… How can I limit LAN bitrate to this TV at 100 or 95 mbps?

EDIT 2:
my 2nd tv which is on Wifi has the same issue:

Though with a much lower bitrate…
The right side of the graph is the 2017 tv, the left side of the graph is the 2020 tv.

Other HDR media is not being transcoded but directplayed:"

So why does Plex need to transcode the other media?

[FordGuy61]

There are several things happening.

1. The Plex Samsung app cannot direct play PGS or VOBSUB subtitles. Enabling them forces a video transcode.

2. The movie is in Dolby Vision format (notice the DOVI info in the media information). Your TV does not support Dolby Vision. Some, but not all, Dolby Vision video profiles will fall back to HDR10. If fallback is not supported, Plex Media Server will transcode the video.

3. When running Windows, Plex does not support HDR Tonemapping using Nvidia GPUs (HDR to SDR Tone Mapping). Plex has limited support for the on-board Intel QSV graphics.

Suggestions:

1. Play the movie with subtitles disabled. See if it direct plays / direct streams. If it still transcodes, you may be better off avoiding that specific Dolby Vision profile, as it cannot fall back to HDR10.

2. Use only SRT subtitles and possibly audio tracks that direct play (AC3/EAC3/AAC). The Plex Samsung app direct plays SRT subtitles. However, on some Samsung TVs, transcoded audio + subtitles results in a video transcode (it depends on the Tizen version).

3. Try assigning Plex to Intel QSV graphics. See this website.

4. If the system is a dedicated to Plex Media Server, consider running Linux. Hardware Transcoding and HDR Tonemapping are fully supported on Linux based systems (HDR to SDR Tone Mapping).

[snovvdog]

1: Okay, thanks, that figures.
Video transcode is not always a bad thing, but why is it transcoding to a 250 mbps stream? Is it possible to limit the transcoding to max bitrate of 100?
2: I was new to HDR media and realised this later, sometimesi t’s hard to see if something is HDR10 or DV.
3. Is support planned for the future?

1. I understand, I will try finding SRT subs instead.
2. I will try to take more care for the video formats when downloading media.
3. Thanks, I will try if this is possible, currently the intel hd gfx are disabled
4. The server doubles as a gaming, work and multimedia pc and running linux is not really an option.

Would more cpu power (and software transcoding) help? As far as I can see the problem is not the transcoding by CPU but the bitrate. That is by far the easiest option, swap the 6 core 8700k for an 8 core 9700k and try to get it at 5ghz aswell (my current cpu manages 5.2 ghz on all 6 cores but runs a bit hot then hence I’m not running it at that) but I don’t think that will solve anything.

Primarily with the Lawrence of Arabia example I reckon the problem is teh excessive bitrate of the transcoded vid, I can understand the buffering by the tv since it is limited by a 100 mbit lan port.