allow users upload their own music file and play a rhythm game

I am currently designing an android rhythm game (similar to guitar hero) in which it can allow user to upload their own music file and the app analyzes the rhythm and then immediately gives falling notes for user to hit and play.

is there any tutorial to teach how to 1. set up a GUI file browser in app for user to upload their own song 2. analyze the music (on server/ within the app) 3. produce a sheet of falling notes according to the rhythm of music??????

My APP can only play with the pre-loaded music and pre-set falling notes but not the music randomly uploaded by users. Please help.....

Thank you very much!!!

there is a similar app called "Beat mp3" which performs the functions i exactly want. but no source code available https://play.google.com/store/apps/details?id=com.studio7775.BeatMP3&hl=en