MKVToolnix is a set of tools to create, alter and inspect Matroska
(and WebM) files. With these tools, you can

* Get information about Matroska files (mkvinfo) 
* Extract tracks/data from Matroska files (mkvextract) 
* Create Matroska files from other media files (mkvmerge) 
* Modify properties of existing Matroska files (mkvpropedit)

MKVToolnix requires wxGTK/wxPython all of which are available on
Slackbuilds.org and it comes with internal versions of libembl and
libmatroska.  Configure will use the internal versions if it fails
to find system ones.

Interested parties can build QT version of GUI by passing QTGUI=yes