How to make a Karaoke video with 2 audio tacks something like track1 and track2?

 Ans.
[ HAVE TO use mp2 as track2(aka. No vocal music) ]
By using MediaCoder to convert MP3 to mp2
By using MKVToolNix to multiplexing MP4 and MP2.

They can be download at
http://www.mediacoderhq.com/download.htm
https://www.videohelp.com/software/MKVToolNix