MKVtoolnix is a set of tools for creating and modifying MKV files. The application is comand-line based, but the Windows version has a graphical interface called the MKVmerge GUI.
There is an amazing list of supported input formats. Although this application is more for advanced users, anyone can use it to perform basic tasks. For example, when you add a video file, MKVtoolnix will return you how many parts the file contains. For example, for an XVID clip, it returns the XVID video part and the AC3 audio part. When you are ready to convert files to MKV, just click the Start muxing button at the bottom of the page.
This free program has options for subtitles, video, audio and format-specific settings. In short, MKVtoolnix can offer a lot of functionality, but when it comes to video files, you can really appreciate its capabilities.
MKVToolnix is a package of tools for working with the Matroska container format (MKA and MKV) and more precisely collecting individual streams (video, audio, subtitles, etc.) in the appropriate format and splitting an MKA / MKV file into its constituent streams. The program offers full use of the capabilities of the Matroska format: embedding more than one stream for video, audio and subtitles, embedding fonts and other files, splitting, creating so-called chapters and more.
License: Free GPL.
Changes in MKVToolnix 52.0.0:
## New features and enhancements
* MKVToolNix GUI: job queue: the maximum number of jobs to run concurrently
can now be increased in the preferences. The default remains
at 1. Implements # 2984.
* MKVToolNix GUI: the GUI will now add a context-specific default extension to
file names selected for saving on platforms that don’t add one itself
(eg GNOME). For example, when saving multiplexer settings the extension
`.mtxcfg` will be added. Implements # 2983.
* MKVToolNix GUI: added an option to the preferences for the window to stay on
top of other windows. Implements # 2967.
## Bug fixes
* mkvextract: h.265 / HEVC extraction: the code for skipping extraction of
prefix SEI NALUs in the first frame was skipping two bytes too few,
resulting in broken processing of all following bytes. Patch by Mike Chen.
* libEBML: the optional, bundled version of libEBML was updated to v1.4.1.
## Build system changes
* libEBML v1.4.1 is now required due to a bug in libEBML that caused pointers
to just-freed memory being returned to the caller under certain invalid data
constellations, causing use-after-free errors in all of MKVToolNix’s
programs. Fixes # 2989.