Create, edit, and play Matroska video files (MKV) on your Mac. Use a common way or the command-line to access the application, select files, modify them, edit tags, and chapters. Adjust the aspect ratio, display width and height, FPS, and other parameters.
MKVToolNix helps you perform various operations involving Matroska (MKV) files, such as creating, splitting, editing, muxing, demuxing, merging, extracting or inspecting them. Its interface is based on a combination of side and top tabs. Although I appreciate the efforts to facilitate the work of the users, I feel that the program is still unnecessarily difficult to use. In this regard, I would recommend a redesign.
So, you should first pick an operation, such as inspecting the file and editing its headings and chapters. Next, it is necessary to choose the source files, set the actions and configure the output parameters. In this regard, it is good to know that formats other than MKV are also supported. Besides, the supported actions include customizing tracks and tags. Similarly, the tool lets you customize the output aspect ratio and a number of frames per second, as well as setting a given delay. What is more, the app supports adding cues to the frames and setting a compression level.
To conclude, it is excellent that MKVToolNix allows performing practically any operation on MKV files. Unluckily, it may take some time before you learn to use it fluently. The product is open source and available for free.