Xbox Series X Transcoding every H.265 file to H.264, regardless of other factors

Plex Players Gaming Consoles
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Server Version#: 1.93.0.144-9b2f4a13
Player Version#: Client: 5.82.2; Platform: 10.0.25398.4478

I’ve got a kind of unique and annoying issue. It seems that whenever I try to play an H.265 MKV file (most of my library), it always transcodes the video. When its a 1080p file, that’s not too big of an issue because my 1080ti handles it well enough, but its a real problem for 4K files (working on building a new dedicated Plex server that will be able to handle a couple of 4K transcodes, but still…). And it is even doing it for some files that it used to direct play. Here is a read-out for a movie I am reasonably sure should and used to direct play video and transcode audio:

General
Unique ID: 230623987671192080335170425205962218769 (0xAD80907AE12E9144925B69779C029D11)
Complete name: K:\Media\Movies\Baby Driver (2017) {tmdb-339403}\Baby Driver (2017).4k.hevc.hdr10.mkv
Format: Matroska
Format version: Version 2
File size: 21.0 GiB
Duration: 1 h 52 min
Overall bit rate mode: Variable
Overall bit rate: 26.7 Mb/s
Frame rate: 23.976 FPS
Movie name: Baby Driver
Encoded date: 2023-02-06 21:01:50 UTC
Writing application: DVDFab 12.0.9.8
Writing library: libebml v1.4.2 + libmatroska v1.6.3

Video
ID: 1
Format: HEVC
Format/Info: High Efficiency Video Coding
Format profile: Main 10@L5.1@High
HDR format: SMPTE ST 2086, HDR10 compatible
Codec ID: V_MPEGH/ISO/HEVC
Duration: 1 h 52 min
Bit rate: 23.1 Mb/s
Width: 3 840 pixels
Height: 1 608 pixels
Display aspect ratio: 2.39:1
Frame rate mode: Constant
Frame rate: 23.976 (24000/1001) FPS
Color space: YUV
Chroma subsampling: 4:2:0 (Type 2)
Bit depth: 10 bits
Bits/(Pixel*Frame): 0.156
Stream size: 18.2 GiB (87%)
Default: Yes
Forced: No
Color range: Limited
Color primaries: BT.2020
Transfer characteristics: PQ
Matrix coefficients: BT.2020 non-constant
Mastering display color pri: Display P3
Mastering display luminance: min: 0.0050 cd/m2, max: 4000 cd/m2
Maximum Content Light Level: 4491 cd/m2
Maximum Frame-Average Light: 315 cd/m2

Audio
ID: 2
Format: DTS XLL
Format/Info: Digital Theater Systems
Commercial name: DTS-HD Master Audio
Codec ID: A_DTS
Duration: 1 h 52 min
Bit rate mode: Variable
Bit rate: 3 333 kb/s
Channel(s): 8 channels
Channel layout: C L R LFE Lb Rb Lss Rss
Sampling rate: 48.0 kHz
Frame rate: 93.750 FPS (512 SPF)
Bit depth: 16 bits
Compression mode: Lossless
Stream size: 2.62 GiB (12%)
Language: English
Default: Yes
Forced: No

When I turn on playback details, I get the following:

File:
Mode: Transcode, speed: 0.7
Container: mkv -> mp4
Protocol: dash

Video:
Codec: hevc -> h264
Resolution: 3840x1608 -> 1920x1080
Bitrate: 25.2 Mbps -> 2147483.6 Mbps
FPS: 23.976 -> 23.976
Aspect: 2.35
Dropped Frames: 10/750 (1.33%)

Audio:
Codec: dca -> aac
Bitrate: 1536 -> 774
Channels: 7.1 ->

Server:
Location: LAN
URI:https://s192-168-1-[rest of the string].plex.direct:[port]

Decision:
Reasons:
Cannot direct play with protocol; http, codec: dca. Reason: Audio passthrough is not available for dca
Cannot direct stream with protocol: dash, codec: dca. Reason: dca is only available with Direct Play
Direct play not available; conversion OK

Right off the bat, the video bit rate seems very wonky. Unless there is a mistake/typo in that line, Plex is trying to transcode a 25.2 megabits/second file to a 2.147 terabits/second file. Everything may be going over CAT5e and decent network hardware, but I suspect that 2.1 terabits is just little beyond what my home network is capable of.

So, is there currently a problem with the Xbox Plex App, where it not only tries to transcode any H.265 file to H.264, but transcode it at insane bitrates? Or am I hunting something else? It’s plausible I might be mis-remembering direct play compatibility for this particular file, but I do know it transcoding every H.265 file, and that is used to direct play some of the files it is now transcoding.

Thanks in advance to anyone who can offer any insight or could point out something I might be missing while trying to troubleshoot.

Plex Media Server.log (1.6 MB)

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May 24, 2024 20:36:41.292 [17876] DEBUG - [Req#28c00/Transcode] MDE: Baby Driver (2017): selected subtitle cannot be converted to a compatible format, burning into video stream

Try de-selecting the subtitle and play again.

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That is one of the first things I try on each offending file. Deselecting subs that force a burn improves the transcoding performance slightly, but it doesn’t seem to prevent a transcode in my case. I am still hunting for some other common factor, but the only one I have found so far is the H.265 codec.

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It is possible that your client is also affected by the “safety transcode” strategy, which is present in a number of smart TV plex clients as well.
As soon as a movie requires transcoding of audio (or the selected audio stream is not the first audio stream in the file) and also has subtitles enabled, the video is transcoded as well, in order to keep audio and video in sync.

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Huh. Well that is interesting to learn, and I admit I had kind of wondered if audio format might have been playing a role, as a lot of the affected files seem to have some form of Dolby audio codec (no particular version of Dolby; Atmos, TrueHD, whatever). It also seems to jive with the reasoning in the playback details (“Audio passthrough not available for dca”)

And to add a little extra ‘fuel’ to this theory, I was just playing around with a couple of other files, and noticed that they were deciding to transcode some Dolby instead of falling back to the AC3 audio on the file. That should be solidly in the realm of being supported by the Plex Xbox app. But when I directly selected it to force it to play AC3, I got no audio out instead (audio direct “played”, but video kept transcoding).

Maybe there is a bug with the Xbox Plex app right now that causes issues with audio transcoding, which in turn triggers a safety transcode of the video as well?

I don’t think it is the TV or sound bar, as neither one is hooked up to the internet, so no way a bug could be introduced to them via an update. It would either have to be a bug/setting on my server, something common to a lot of my files, or a bug/setting on the client device.

6

I think you’re onto something with the audio pass-thru stopping direct play. I’ve been having issues but mostly with newer rips that have atmos audio.

It’s be great if at least one platform would do everything right on Plex. So many people still using shields and Xbox used to be one of the best supported and stable platforms. Now it’s giving me issues daily and no one can say how to roll back to an old version.

7

I actually learned something just yesterday about my setup.

I am passing my signal through a harman kardon Enchant 800 sound bar, but to a kinda basic Samsung TV that only supports HDR10 (no HDR10+, and obviously no DoVi). But that should not matter: The Enchant 800 supports DoVi with HDR10 fallback, even on pass through.

Or it did when I bought it.

I was poking around Xbox’s video settings at:

Settings > TV & Display Options > 4K TV Details

And realized it was reporting incompatibility with pretty much everything. All HDR formats, higher refresh rates, higher bit rates. Everything. After some troubleshooting, what I discovered is that it was my sound bar that is causing the issues. If I take it out of the system, the Xbox reports compatibility with pretty much everything except DoVi (no surprise there). And, yes, I tried swapping cables around to make sure that wasn’t it.

While it is no longer connected to the internet, this sound bar was at one time connected (a long time ago). My suspicion is that for some reason Harmon Kardon - either accidentally or on purpose - broke/removed DoVi pass-thru, and this then broke HDR10 pass-thru and higher bitrate pass-thru. They probably also broke Dolby Atmos around the same time. Right now, on HK’s website, it looks like they might have exited the sound bar market. Maybe they stopped paying Dolby their licensing fee (or something to that effect), so disabled those features in all of the sound bars that were connected to the internet?

Regardless of how it happened, it seems this broken compatibility with Dolby content - combined with possibly some other broken Plex compatibilities - is what is resulting in having to transcode everything. Because I think the only movies I have found that play directly are ones without any kind of HDR format - no DoVi, no HDR10+, no HDR10, etc - and no Dolby sound of any kind.

I am going to get a new sound bar and see if that improves anything (and then never, ever hook it up to the internet - I’ll fill its ethernet port with resin and install an attenuator onto its antenna if I have to)

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