support | how to mix 2 audios files

Hey everyone,

It's been days that I am searching all over google for that piece of code that doesn't
need to be so complicated.

I have an mp3 file stored in my app at res/raw.
I want to create a code that need to do a few things.

1. record the user of the app.
2. mix that record with the mp3 file.
3. convert that mix to an mp3 file.

The mix need to combine simultaneously my voice record and the mp3 file. In other words
the mp3 file need to be in the background.

More over, I want the mix file to be as long as my voice record, for example:
1. if my voice record is shorter than the mp3 file, the mix file need to cut the mp3 file
from the end of the voice record.
2. if my voice record is longer than the mp3 file, the mp3 file need to be played in loops
until the voice record end.

I found a few tutorials on the web, but evertytime I implement those tutorials,
the final output was a white noise (distortion).

It is very important for me,
Thanks for all the help.

** I am willing to pay for that code..*