Server Version#: 1.24.2.4973
Player Version#: latest Web/Apps
As soon my MKV files contain WebVTT subtitles, the Plex server simply can’t open/decode the file.
Could you add support for WebVTT please?
Please read what I wrote: As soon my MKV video container contains WebVTT subtitles the MKV file is no longer supported. It works just fine with integrated SRT subtitles.
This has nothing to do with “poorly encoded/damaged”.
I suspect you’re using “External” VTT files which is a different use case.
I happened to see the messages start coming into my email (I get every Linux and Synology post – when the forum cooperates)
Given your subtitle is external, is there a way to simply check it?
I’ve had SRT errors drive me nuts to find.
I’m thinking of a subtitle - linter online.
I do see this.
Possible?
(pull the subtitle track out using MKVToolnix GUI)
Yeah bad subtitles cause me to see conversion failures. It wasn’t until I looked at the debug logs for my server that I found that was the cause. Try looking at those.
Maybe there is something specific about WebVTT which is not yet quiet supported by plex.
Because I’ve had no issues with playing that same mkv with VLC (with subtitles).
Ok, as a demonstration I picket one of the WebVTT examples and put it together with a 2sec blank video example. It’s exactly the same video (with the same encoding! @trumpy81!).
You will notice that the one without the subtitles plays just fine, while the other one stops with “Conversion failed. The transcoder exited due to an error.”.
I couldn’t find anything helpful inside the logs.
And please note: both examples work just fine in other players.
examples.zip (20.8 KB)
@kfort @ChuckPa
I’ve updated the examples. Added SRT example.
Looks like Plex is handling different types of subtitles differently in sense of priority.
I have no idea who’s able to take a closer look at the Plex functionality to understand why the VTT example is just causing that failure.
examples.zip (37.6 KB)
I can confirm this issue as i have the same problem in my environment (QNAP NAS, PLEX running as Docker Container). As stated in this discussion on Reddit, it seems that the error occurs with embedded subtitles only because ffmpeg does not support it atm. It seems to work as expected, if you have an external WebVTT file.
@dts2k thanks for the confirmation and the Reddit link.
I could find a similar discussion on ffmpeg comments about the same time ago (5-6months).
https://trac.ffmpeg.org/ticket/5641
@ChuckPa @dts2k @kfort
I did another example with external vtt files to clarify that PLEX does not fully support the WebVTT standard. (Web Video Text Tracks Format (WebVTT) - Web APIs | MDN)
You will find 2 vtt files (eng & deu).
DEU will work just fine while ENG simply doesn’t do anything.
The only difference is the STYLE section, which is missing in DEU.
And as soon you have something like that in your embedded MKV, plex player just crashes with an error.
To me this is simply a bug and should be reported to the devs.
external_subtitles.zip (4.2 KB)
I have submitted the logs and documentation to Engineering for triage and disposition.
Be advised, if dependent on any upstream FFMPEG changes, any potential work will be delayed further until such time as that is available.
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For your reference, there is an upstream ticket for S_TEXT/WEBVTT
https://trac.ffmpeg.org/ticket/5641
I have added this to the internal.
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