thanks for your help TheEagle.
I read your post many times and I got a idea and ended like this
so basically, the concept is same and even familiar with the most karaoke fx out there, the only different is the program, how to create and produce the karaoke. And the basic karaoke I made from the picture above just like this.
You can see that "A2" have more 2 keyframe, and I just playing around with advance setting and i got that effect. I just change Shape mode from Square to Ramp Down. for "A3" too. And yeah the Transition Start and End issue is no longer appear, but for the fast song, I still got Transition Start and End issue
(I can fix it manually)
Now, I'm gonna playing around with those setting
Thanks for your help TheEagle. I really appreciate.