One S 4K forcing transcode

Plex Players Gaming Consoles
1

On my One S connected to a 4K screen, plex transcodes (well tries to) a 4K TV show. I get a few seconds of video, then a pause.
The codec’s the file uses are supported by the One S (link)
What’s also weird is that in the plex player, it says it’s playing the video in original 4K 62Mbps quality.
Any ideas why it’s happening?

Media

Video Resolution 4K
Duration 1:01:43
Bitrate 63870 kbps
Width 3840
Height 2160
Aspect Ratio 1.78
Container MKV
Video Frame Rate 24p
Video Profile high
Part

Duration 1:01:43
Size 27.54 GB
Container MKV
Video Profile high
Codec H264
Bitrate 61959 kbps
Language English
Bit Depth 8
CABAC true
Chroma Subsampling 4:2:0
Duration 1:01:43
Frame Rate 23.976 fps
Frame Rate Mode cfr
Height 2160
Level 5.1
Pixel Format yuv420p
Profile high
Ref Frames 5
Scan Type progressive
Width 3840
Codec EAC3
Channels 5.1
Bitrate 640 kbps
Language English
Audio Channel Layout 5.1(side)
Bitrate Mode CBR
Dialog Norm -31 dB
Duration 1:01:43
Sampling Rate 48000 Hz
Codec SRT
Language English
Format SRT
Title English
Codec SRT
Language English
Format SRT
Title English (SDH)

On top of this frustration, my Samsung TV can play the video without asking Plex to transcode, but it needs to pause every 10 seconds to buffer… And I’m connected to Gb ethernet!

2

There is a number of things in your file that could be causing an issue.

The support page you linked shows that eAC3 is not supported in an MKV container. This will cause a transcode because remuxed files currently will go down to 1080p.

Subtitles will cause a transcode as well if they are enabled for the Xbox One App.

4K 264 video also causes a problem for the Xbox One decoder. The last I heard was the issue was referred to Microsoft to look into the decoder issue and direct play of 4K H264 files was disabled.

In any of the above cases, your Plex Media Server.log file will tell you exactly why your file is transcoding shortly before the transcoder is called.