MKVtoolnix 8.1

Set of open-source MKV video converter with MKV merging capabilities
4.1  (94 votes)
12.0.0 (See all)

MKVToolNix GUI is an open-source user interface for a set of highly useful MKV-related tools. Here you can merge MKV files, split them into smaller parts, extract their various audio and video streams, edit their headers and chapters, and convert video files of the most popular video formats into MKV containers.

This MKV toolbox includes three main utilities – mkvinfo, to provide you with extensive technical information about a selected Matroska file; mkvextract, to extract data and streams from Matroska containers, and mkvmerge, to convert MKV files from other media files or to create new ones. Mkvinfo comes with its own GUI, while the other tools have been neatly integrated into MKVToolNix GUI. Here you can add as many supported video files to the conversion list using the Input tab – you will be presented with a parallel list of all the tracks included in the various files and the specific codec they use, as well as the language code assigned to them. You can select which tracks will be muxed and therefore included in the resulting MKV file, give them a new track name, a new language code, extra conversion parameters, etc. The Output tab will let you add metadata and new chapters to the output MKV file, and split it into various segments by size, duration, timecodes, etc. Finally, you can add so-called “attachments” to the Matroska file, such as pictures, fonts for subtitles, background information in text form, etc.

Once you are happy with the way you designed your MKV file, you can either put it on hold using the “job queue” option or launch the conversion process right away. During the conversion/creation process you will be given extensive information in real time in the form of a log – here you will see the job being carried out, the time elapsed, the resulting files, etc.

You may also edit the chapters and headers of existing MKV files using the options provided. You can change the headers of both the video and audio tracks included in a Matroska container, and thus crop the video image (by determining the number of pixels to remove from the top, bottom, right, and left sides of the frame), change the aspect ratio, its width, height, and length, or change the sampling frequency, the bit depth, or the number of channels of a given audio stream. Finally, chapters can be added either manually or by importing the corresponding values from an XML file.

MKVToolNix GUI is an excellent Graphical User Interface to help you perform professional and highly technical edits to your MKV files as well as to create or merge Matroska files in a more relaxed and simple way. Regardless of the use you will be making of it, this is certainly a tool worth having installed on your computer.

Francisco Martínez
Editor rating:

Review summary


  • Professional MKV editing and conversion.
  • Provides extensive information on any Matroska container.
  • Edits MKV's headers and chapters.
  • Powerful MKV merger.
  • Supports the most popular video and audio formats


  • None
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