Adding audio to specific MKV chapters

[zomzom82]

Longtime lurker, first time poster here.

I'm currently having a problem that is driving me up the wall. I'm currently in the process of merging a set of music videos ripped from DVD, using MakeMKV. The issue is that I want to keep the commentary tracks on the individual videos. My approaches so far has been using MKVToolNix GUI 38.0.0 which has otherwise served me well so far. But I'm open to trying some other software as well to accomplish this.

First issue:

* Most of the videos only have two audio tracks while a few of them have three. Just merging everything gives me an error that files can't be amended to itself, or something equivalent. After researching this for a while, it appears that MKVToolNix trips up on the differences between the files, so that this might not be possible. My thinking was: Oh, well just merge everything excluding the extra audio tracks on the few files with more than two, and add the extra commentary tracks later. The files merged flawlessly but I'm still left with the issue of the third audio track for a few of the videos:

* I've been able to extract the extra audio from the first video in the set, which syncs perfectly with the start of the merged file, but is it then possible to add the other tracks to specific chapters? If I for instance have audio for chapter one, four and seven, is there a way to place these audio tracks at specific points in the merged file? And do I need anything else to accomplish this?

Any help is more than welcome, as I'm sincerely struggling to get anything done with this while this is constantly brewing in the back of my mind.
Cheers!

[netmask56]

You will need to lay the complete mkv video track in a video editor. lots to choose from, and then lay the audio tracks as separate elements that sync to the appropriate timings outputting a mkv file with one video element and one matching audio track. Take a note of the entry timings of each song and then make a chapter file to correspond.

[zomzom82]

Thank you for this, truly!

I was frankly dreading that answer, but it at least prompted me to just get on with it. And now, after absolute ages, I finally did the work and learned a lot along the way.

Cheers!!