Why is Plex transcoding this file?

Plex Players Gaming Consoles
1

I am trying out my first 4k stream and seeing significant buffering and was hoping someone understood this repeating error code I get about every 20 seconds:

[0x7f4c467fe700] ERROR - handle_stream_read error 335544539 short read

I am using an XBOX One S as a client and a new Samsung SUHD panel. The client is set to allow Direct Play but the Plex web client says both the Audio and Video are being transcoded but also shows the starting codecs as being something they are not.

H264 to H264
AAC to AAC

This is the mediainfo output for the file:

General
Unique ID                                : 229008010426321667033560276337746999822 (0xAC4956A6863AE7ACAEBB9827673B7A0E)
Complete name                            : Deepwater Horizon (2016) (2160p).mkv
Format                                   : Matroska
Format version                           : Version 4 / Version 2
File size                                : 39.6 GiB
Duration                                 : 1h 47mn
Overall bit rate mode                    : Variable
Overall bit rate                         : 52.8 Mbps
Encoded date                             : UTC 2017-01-29 19:31:09
Writing application                      : mkvmerge v9.7.1 ('Pandemonium') 64bit
Writing library                          : libebml v1.3.4 + libmatroska v1.4.5

Video
ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5@Main
Codec ID                                 : V_MPEGH/ISO/HEVC
Duration                                 : 1h 47mn
Bit rate                                 : 46.4 Mbps
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 23.976 (23976/1000) fps
Original frame rate                      : 23.976 (24000/1001) fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 10 bits
Bits/(Pixel*Frame)                       : 0.233
Stream size                              : 34.8 GiB (88%)
Writing library                          : x265 2.2+22-20217c8af8ac:[Windows][GCC 6.2.0][64 bit] 10bit
Encoding settings                        : cpuid=1173503 / frame-threads=5 / numa-pools=14,14 / wpp / no-pmode / no-pme / no-psnr / no-ssim / log-level=2 / input-csp=1 / input-res=3840x2160 / interlace=0 / total-frames=155097 / level-idc=0 / high-tier=1 / uhd-bd=0 / ref=3 / no-allow-non-conformance / no-repeat-headers / annexb / no-aud / no-hrd / info / hash=0 / no-temporal-layers / open-gop / min-keyint=23 / keyint=250 / bframes=4 / b-adapt=2 / b-pyramid / bframe-bias=0 / rc-lookahead=20 / lookahead-slices=8 / scenecut=40 / no-intra-refresh / ctu=64 / min-cu-size=8 / no-rect / no-amp / max-tu-size=32 / tu-inter-depth=1 / tu-intra-depth=1 / limit-tu=0 / rdoq-level=0 / signhide / no-tskip / nr-intra=0 / nr-inter=0 / no-constrained-intra / no-strong-intra-smoothing / max-merge=2 / limit-refs=3 / no-limit-modes / me=3 / subme=2 / merange=57 / temporal-mvp / weightp / no-weightb / no-analyze-src-pics / deblock=-3:-3 / no-sao / no-sao-non-deblock / rd=3 / no-early-skip / rskip / no-fast-intra / no-tskip-fast / no-cu-lossless / no-b-intra / rdpenalty=0 / psy-rd=3.50 / psy-rdoq=0.00 / no-rd-refine / analysis-mode=0 / no-lossless / cbqpoffs=0 / crqpoffs=0 / rc=crf / crf=14.0 / qcomp=0.60 / qpstep=4 / stats-write=0 / stats-read=0 / ipratio=1.40 / pbratio=1.30 / aq-mode=2 / aq-strength=1.00 / cutree / zone-count=0 / no-strict-cbr / qg-size=32 / no-rc-grain / qpmax=69 / qpmin=0 / sar=1 / overscan=0 / videoformat=5 / range=0 / colorprim=1 / transfer=1 / colormatrix=1 / chromaloc=0 / display-window=0 / max-cll=0,0 / min-luma=0 / max-luma=1023 / log2-max-poc-lsb=8 / vui-timing-info / vui-hrd-info / slices=1 / opt-qp-pps / opt-ref-list-length-pps / no-multi-pass-opt-rps / scenecut-bias=0.05 / no-opt-cu-delta-qp / aq-motion
Language                                 : English
Default                                  : Yes
Forced                                   : No
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709

Audio #1
ID                                       : 2
Format                                   : Atmos / TrueHD
Codec ID                                 : A_TRUEHD
Duration                                 : 1h 47mn
Bit rate mode                            : Variable
Bit rate                                 : 5 036 Kbps
Maximum bit rate                         : 6 759 Kbps
Channel(s)                               : Object Based / 8 channels
Channel positions                        : Object Based / Front: L C R, Side: L R, Back: L R, LFE
Sampling rate                            :  / 48.0 KHz
Frame rate                               : 1 200.000 fps (40 spf)
Compression mode                         : Lossless
Delay relative to video                  : 1s 100ms
Stream size                              : 3.77 GiB (10%)
Language                                 : English
Default                                  : Yes
Forced                                   : No
2

The file is h265, which I don’t believe is supported currently by the Plex Xbox One application. So it is transcoding to h264. That’s my best guess anyway, would need the server logs while trying to play the file to be precise.

I know there was some testing on h265 and maybe that was kept around, but Atmos isn’t currently supported for 3rd party apps anyway. So the audio needs to be transcoded which in turn requires the video to be transcoded as well to h264.

3

@adamskoog said:
The file is h265, which I don’t believe is supported currently by the Plex Xbox One application. So it is transcoding to h264. That’s my best guess anyway, would need the server logs while trying to play the file to be precise.
Close, HEVC is supported but only via direct play. What you said below is actually correct. Because the audio needs to be transcoded the HEVC needs to get transcoded into h264 so it can be put in the HLS stream.

I know there was some testing on h265 and maybe that was kept around, but Atmos isn’t currently supported for 3rd party apps anyway. So the audio needs to be transcoded which in turn requires the video to be transcoded as well to h264.

4

Close, HEVC is supported but only via direct play. What you said below is actually correct. Because the audio needs to be transcoded the HEVC needs to get transcoded into h264 so it can be put in the HLS stream.

This is good to know. From what I’m reading it looks like not only will it be transcoded to h264 but also down to 1080p. I’m going to try to optimize the file down to a compatible audio format. This loosely XBOX related but if the XBOX is connected to the TV and then TV to soundbar via optical does Plex get the info on what codecs are supported from the TV or another source?

5

@brianskinder@gmail.com said:
This is good to know. From what I’m reading it looks like not only will it be transcoded to h264 but also down to 1080p. I’m going to try to optimize the file down to a compatible audio format. This loosely XBOX related but if the XBOX is connected to the TV and then TV to soundbar via optical does Plex get the info on what codecs are supported from the TV or another source?

You are correct about transcoding down to 1080p with h264. This is mostly due to the Xbox decoders having issues with h264 4k material. Once that is fixed 4k with h264 will be possible (Depending on the server CPU speed)
For available codecs it all dependent on the device running the app. There is no way to query what an external device (IE Sound Bar/Receiver) support. However, Microsoft is currently testing bit streaming/passthrough support. What this means is you will be able to tell the app to pass the audio through as is anyway. But until that comes out fully and to 3rd party developers it’s just a guess how it will work with 3rd Party Apps. (All we know at this time is that it is coming to 3rd party apps, but not when).

Also, if you’re using ARC (Such as Xbox One → TV → Sound bar) you need to be careful as some ARC setups have limited codec support. On my setup using ARC DTS is not supported so I need to switch my TV’s ARC mode out to Dolby Digital, and others have reported only having support for 2.0.

^Sorry if this is a bit too much, but figured I would give you my experience with it as well.

6

Sorry if this is a bit too much
No its great! This is a new setup so I’m hungry for as much info as I can find. And its little things like that that will drive you crazy when you’re expecting a specific result and not getting it.

7

@jmckee said:
However, Microsoft is currently testing bit streaming/passthrough support.

Are we certain this will be true passthrough? I’ve got the Xbox One beta release and the only option I see is Dolby Atmos under Dolby Digital. The Dolby Atmos option doesn’t do anything yet…it’s just there as a placeholder, but since they didn’t call it “pass through” it leads me to believe it’ll function the same as the current DTS and Dolby options. I certainly hope they provide true passthrough though.

8

@mbarylski said:
Are we certain this will be true passthrough? I’ve got the Xbox One beta release and the only option I see is Dolby Atmos under Dolby Digital. The Dolby Atmos option doesn’t do anything yet…it’s just there as a placeholder, but since they didn’t call it “pass through” it leads me to believe it’ll function the same as the current DTS and Dolby options. I certainly hope they provide true passthrough though.

I am not a part of the insider preview myself. However there should be a setting for it in the bluray settings (found from a guide):

  1. Make sure your console is plugged in via HDMI to an audio receiver which supports decoding of Blu-ray audio formats. Optical audio does not support pass-through.
  2. Enable “Let my receiver decode audio (beta)” under the “Disc & Blu-ray” settings page.

As far as I have been told its currently only available for the bluray settings so it shouldn’t be under the general settings. But from what I have been told it is a completely full passthrough support.

9

Yes, Blu ray is full passthrough. I’ve tested that and it works great. It’s a different setting for 3rd party apps though, which uses the global settings. At the moment the global setting only says Dolby Atmos, which indicates 3rd party apps won’t have full passthrough. I’m REALLY hoping they change that though. We should know for sure in a week or 2 hopefully.

If you’re interested you might be able to join the program now by installing the Xbox insider app. I could be wrong but I thought they got rid of the invite only requirement.

10

@mbarylski said:
Yes, Blu ray is full passthrough. I’ve tested that and it works great. It’s a different setting for 3rd party apps though, which uses the global settings. At the moment the global setting only says Dolby Atmos, which indicates 3rd party apps won’t have full passthrough. I’m REALLY hoping they change that though. We should know for sure in a week or 2 hopefully.
There was a quote floating around from twitter where Mike Ybarra stated it was coming to everything “eventually”.
http://forums.plex.tv/discussion/comment/1333575/#Comment_1333575

And that eventually is the big question that no one knows ( At least not outside of Microsoft)

If you’re interested you might be able to join the program now by installing the Xbox insider app. I could be wrong but I thought they got rid of the invite only requirement.

Yeah, The problem is my equipment isn’t setup in a way that would take full advantage of the preview program. So it wouldn’t be very beneficial to me or for me to try and report issues. Mostly due to the ARC setup I have where I can’t use any DTS formats (Or HD Audio formats) which would mean I would actually be worse off myself trying to use passthrough right now. But someday when I convince the wife that we need to upgrade our home theater system, it will make things better for me!