Is there any video player for Ubuntu that supports the TTML (Timed-Text Markup Language) subtitle format?
I have tried VLC (version 2.2.2). Neither MPlayer supports it according to its documentation.
Try VLC 3.0 or more.
3.0 Features : TTML subtitles support, including EBU-TT variant
I've tested it with VLC 3.0.3. It work but I had to change the file extension from .ttlm to .txt in order to be able to select the file.
TTML Subtitle Example : https://gist.github.com/anotherhale/676a72edc84ca3a37c0c