So you've read about mkvmerge / MKVToolNix / MKVToolNix GUI, and want to use these video tools on your Mac: The latest version of the GUI (25.0) will work only with Mac OS X 10.11 and higher, because of an update of the Qt version (Qt is the GUI library MKVToolNix GUI is built with). This new version of Qt, which only supports El Capitan and later, was implemented after version 24.0 of MKVToolNix GUI.
Summary: download MKVtoolnix for macOS to edit MKV multi-track video files on macOS with ease.
MKVToolNix is an all-in-one MKV toolbox that gives you free access to mkvmerge, mkvinfo, mkvextract, mkvpropedit, etc, ready for you to modify, merge, subtitle, create and extract MKV videos under Linux, other Unices and Windows. But to get the Mac version is a hard nut for most users. For more clues and hints to download MKVToolNix on Mac OS X, there is no need to turn around other guides. Just click the links below that will direct you to specific part of the free MKV video editor for Mac.
The process of downloading the toolbox on Mac platform is a little tricky, but you can follow the steps below and get the right dmg of the free MKV editor on your Macbook or iMac.
Step 1: Go to fosshub, where the version 17.0.0 is offered.
Step 2: Choose Download MKVToolNIx macOS. The file size is around 19.89 MB. It won't take a long time.

Remuxing refers to a lossless process of changing the format from one another, e.g. from MP4 to MKV, AVI to MKV, etc without something such as audios or subtitles one doesn't want, thus reducing the file size and saving space. Just follow the steps below and learn how to remux files to MKV.
There are also other settings, for more information, please go to: https://mkvtoolnix.download/doc/mkvtoolnix-gui.html
This MKV remuxing tool is praised for its powerful free MKV editing features. It allows you to change the track name, language, default and forced tracks, timecodes, add cues for the frame, change the compression mode, split video, etc. However, there are still some pros and cons. Take a look at them.
Allow to modify many aspects of MKV files, including merge, crop, trim, tracks, subtitles, chapters, etc.
The speed of MKV conversion is impressive.
Doesn't change the quality of the source video.
Works only on MKV videos.
No user guide.
Not the intuitive interface.
Various errors such as not showing subtitles, no sound error, etc.
Editing MKV files with MKVToolNix can be a challenge for most Mac users, not only because of the relatively hard process to download it, but also for its complicated UI for novice users to interpret, let along the reportedly errors with it, such as V9.7.1 DMG is missing a library and leads to a crash, subtitle not showing, no sound/audio/subtitle, no extra compression, etc.
To restore to an alternative to get rid of these problems, MacX Video Converter Pro is highly recommended - an easy-to-use yet professional MKV editor for Mac with a raft of additional features, from basic MKV video editing like trim, crop, rotate, split, flip, cut MKV files to advanced ones such as select/add subtitles to MKV, extract audio from MKV, and even tweak the video resolution, bit rate, frame rate, codecs, and reencode videos like MTS, MOV, AVI, MP4 to MKV with audio/video tracks and subtitles reserved. You can follow the steps below to edit MKV on Mac with MKVToolNix alternative.
Step 1: Free download MacX Video Converter Pro. It makes great compatibility with even the latest macOS High sierra.
Step 2: Import the source video, be it MP4, MOV, HEVC, H264, AVI, WMV, FLV, MTS, AVCHD or TOD, MOD.
Step 3: Choose the output format MKV. There are as many as 400 preconfigured profiles, ready for the latest mobiles, including iPhone 12/11/Max Pro, Samsung Galaxy S21, 4K Apple TV, and more. You can also reencode the source video to MP4, HEVC, AVI, WMV and other mainstream formats.
Step 4: Click Edit button to trigger off the MKV video editor feature.

Step 5: Click Browse to save the output file and Tap RUN to begin the MKV video edition.
I streamed a few DJ sets over the last few weeks with a bunch of friends as part of ‘covidcore’, an online get-together while we’re all in isolation. It’s been a while since I’ve played any DJ sets but it was great fun and thankfully I didn’t make too many mistakes.
Anyway, It was my first streaming experience and I found it a breeze to set up thanks to Twitch and OBS. When reviewing my recordings I noticed that my microphone level was pretty low so I decided to bust out the audio track from the video and raise it. Also when uploading my video to Youtube I also got a copyright notice about one the clips in my video which was subsequently being blocked, so I decided to edit that out too.
Here is how you can do it.
Note: I’m on a mac so all of the instructions are for that, but apart from installation the rest should be platform agnostic.

mkvtoolnix is a set of command line programs for finding out information and modifying mkv (“Matroska”) files. You can install it with a GUI but I didn’t bother.
That’s it, boom!
For this step we are going to run this command
In the above command we are using mkvextract, part of mkvtoolnix, to extract the video track which is encoded using the ‘h264’ codec and also the audio track which is encoded using the AAC codec.
In order to find out what your video and audio tracks were encoded with use the following tool
Might be good to reference the docs if you have trouble there.

My audio editor couldn’t open the aac file I created so I converted it to FLAC format using ffmpeg, another command line program that is insanely useful for converting audio formats (amongst other things).
So to convert I ran
Now I can open my flac file and edit the parts I want, like amplifying my microphone in the recording.
Right, now you have completed your editing we can stitch them back together again using the mkvmerge command
You can see I just merged the flac formatted audio back in. I just tried it and it worked. I need to read up a bit more on file formats to be honest so if you need more info check the docs.
Hope that helps someone :)