MKVToolNix is one free application for editing MKV files. With the free application you can cut a large file into smaller pieces, or vice versa to join smaller pieces into a larger one. You can save MKV audio to Mp3 but also easily incorporate subtitles.
It is a very practical tool for those who have Movies HD movies on their computer and want to edit them. 
The developer of MKVToolnix project Moritz Bunkus announced the release of the new MKVToolnix 15.0.0. It is a large version of open-source and cross-platform (Windows, Linux and Unix) application of MKV (Matroska).
MKVToolNix 15.0.0 “Duel with the Devil” was released exactly one month after the release of MKVToolNix 14.0.0 “Flow”, and it seems to add a lot of new features and improvements, along with several bug fixes and some changes to system.
The new MKVToolnix 15.0.0 comes with a new, much more practical GUI that supports editing video color features.
You can see all changes from release notes and of course to
download the application to the platform you want
