Android audio mixing using Pyjnius [http://pyjnius.readthedocs.org/en/latest/android.html].

trainwreck.py

from jnius import autoclass
from time import sleep

MediaPlayer = autoclass('android.media.MediaPlayer')

ones = MediaPlayer()
ones.setDataSource("/sdcard/Music/05 Steve Miller Band Fly Like An Eagle Remix.mp3")
ones.prepare()

twos = MediaPlayer()
twos.setDataSource("/sdcard/Music/04 Jay Z Empire State Of Mind Remix.mp3")
twos.prepare()

print 'duration:', ones.getDuration()
ones.start()
twos.start()

while ones.isPlaying() or twos.isPlaying():
  for vol in range(0,100):
		ones.setVolume(vol/100.0,vol/100.0)
		twos.setVolume(1-vol/100.0,1-vol/100.0)
		print 'current position:', ones.getCurrentPosition()
		sleep(.1)
	for vol in range(100,0,-1):
		ones.setVolume(vol/100.0,vol/100.0)
		twos.setVolume(1-vol/100.0,1-vol/100.0)
		print 'current position:', ones.getCurrentPosition()
		sleep(.1)


ones.release()
twos.release()