I have a MP4 and MKV video file which also has its own Audio track. I want to add an additional track to it to cover another language for it, what Terminal or GUI way is there available to insert and sync a MP3 file to the already existing video so that:

• The video shows 2 audio tracks (The existing one and the new one am inserting)


• Optionally the video shows the name of the tracks


• I can sync the new audio with the video


• I do not replace the existing audio with the new one


• Maintain the same video quality as before
  
  (It is a 1080p video with very high details. Do not want to mess with this since it takes way too long to get it right)

This would help in, for example, adding additional language sound tracks to an existing video.