Embedded Subtitles Missing

General Discussions
1

Hello!

Is there any particular reason why I cannot access embedded subtitles on some video files? Depending on the viewing method I sometimes get the option to select the subtitles (i.e. if I use plex web I can select subtitles from the drop down menu before playing the selected content) but if I access the same file video on my phone (Android App) it simply says subtitles “none” at the menu. Same occurs for my Android TV (makes no difference if you start playing the file and then go to options to select subtitle, just says none). I can view the subtitle details in the file details, some even have a dozen languages embedded yet this is not displayed to play.

At first I thought it may be a transcoding issue but even when my devices can direct play the content I still cannot select subtitles at any point.

Example from file details (Plex Web) within Plex:
"Codec HEVC
Bitrate 1950 kbps
Language English
Bit Depth 10
Chroma Subsampling 4:2:0
Color Range tv
Frame Rate 23.976 fps
Height 800
Level 4.0
Profile main 10
Ref Frames 1
Width 1920

Codec AAC
Channels 7.1
Bitrate 478 kbps
Language English
Audio Channel Layout 7.1
Profile lc
Sampling Rate 48000 Hz
Title English 7.1

Codec AAC
Channels Stereo
Bitrate 50 kbps
Language English
Audio Channel Layout stereo
Profile he-aac
Sampling Rate 48000 Hz
Title Commentary

Codec PGS
Bitrate 11 kbps
Language English
Header Compression 1

Codec VOBSUB
Language English
Header Compression 1

Codec VOBSUB
Bitrate 4 kbps
Language العربية
Header Compression 1

Codec VOBSUB
Bitrate 5 kbps
Language Nederlands
Header Compression 1

Codec VOBSUB
Bitrate 5 kbps
Language Français
Header Compression 1"

This is 1 10bit version of this file, I have 2 other copies with subtitles also (8bit files) but these are not options when viewing on Android TV or the Android App. However when viewing this file through Plex Web I can then select subtitle options in content menu before pressing play.

I am trying to figure out the cause of this problem because at the moment I have many family members viewing content through Android apps and they are complaining of missing subtitles when I know for a fact there are subtitles embedded. I have other HEVC files with VOBSUBs and you can select them in the menu at any time while streaming the respective file.

I am running the latest media server and all apps for viewing are always up to date.

2

Header Compression is almost always the cause.

The most direct verification is to remux the mkv and expressly disable header compression from the output file.
Save the input file; put the output in place of the original; have PMS update its analysis of the file so it sees the change.

3

@ChuckPA Can you provide a Windows command line help for what you are tring to tell us?

Which program (Windows command line) with which options, since I have the same issue.

4

MKVtoolnixGUI for all things MKV
brings a command line tool as well

5

I can confirm, that this is the problem in my case… Remuxing the embedded VOBSUB (bitmap) subtitle tracks to not use (zLib) compression, did show them on the Amazon Fire TV v2.

Time to find a solution for zLib subtitles on the player app side.