Android Capturing Audio Stream and translating it into pcm data for effects

How can I capture the audio stream in Android - (the music that is currently being played) and create a buffer so that I can add effects to it.

I plan on allowing the user to change the volume through the app as well as pitch.

Is something like this: Increase volume output of recorded audio going to work?

EDIT:

Some other Stackoverflow questions deal with taking the microphone input as the input of the audio stream. I would like to do something similar, but instead have the playing audio on the device be the input.