MKVToolNix
Set of tools to work with Matroska files - GUI frontend
MKVToolNix is a set of tools to create, alter and inspect Matroska files under Linux, other Unices and Windows.
Matroska is a new multimedia container format, based on EBML (Extensible Binary Meta Language), which is a kind of binary XML. . The mmg tool is a graphical user interface for the mkvmerge program, which allow one to create Matroska files from other formats. . This package also contains a graphical version of the mkvinfo tool, which allow one to get information about a Matroska file.
How to install MKVToolNix in Ubuntu
If you are on a supported distro like Ubuntu, Linux Mint, elementary OS etc. you can install the application through software center by clicking the below link.
If the above link not working, run the below command in terminal to install mkvtoolnix-gui in Ubuntu
sudo apt install mkvtoolnix-gui
MKVToolNix Screenshots

