inserting additional audio track to mkv file ?

[Anakunda]

hello, i got a mkv video with 2 audio tracks and i have external audio track which i want to insert into the video with certain time shift and make it default, retaining existing audio tracks. is this possible using mkvtoolnix or another toolset, without necessity to reencode?

[sneaker_ger]

Yes, it's possible using mkvtoolnix (given your tracks are supported by it). Open your mkv video using mkvmergegui, add the audio. You can then set the delay and default flag of the audio. Deactivate the default flags for the other audio tracks. (I'd also move the audio track to the second position in case you end up with a splitter that ignores the flags.) Then mux.