I have just started using processing and minim and i would like some advice from more advanced people.

I am trying to make a small program using minim to crossfade 2 songs ( 1 song is playing and after an event, the previous song fade out and the next sound fade in, the previous and the next song can be the same song ) and i got some problem with it. I am using AudioPlayer object and the method ShiftGain.

First one is that when I use the method  shiftGain(float from,float to,int millis) to make the fade in or the fade out, the transition is quite rough and I would like to know if there is any way to improve the transition. 

The second one is that when I am trying to crossfade the same sound, it doesn't work. The song ( the previous one ) just shut down and there is only the fade in of the next song ) and but it kind of works with different sounds. I would like to know where my code is wrong.

P.S I know where my code is wrong, before the fade out is finished, I rewind the player associated to the song. i dont want to duplicate with another AudioPlayer Object. is there anyway to fix this ? 

The last one My songs are mono(left) and when I using processing and minim, I have some noise on my right which quite annoying. Can i suppress this noise? 

 This is my following code

2. import ddf.minim.*;
3. 
   
4. Minim minim;
5. AudioPlayer [] player;
6. int numberOfsong; // number of songs
7. int currPlayer;        // integer to know which song is playing
8. 
   
9. void setup()
10. {
11. size(100, 100);
12. 
    
13. minim = new Minim(this);
14. numberOfsong = 2;
15. currPlayer = 0;
16. player = new AudioPlayer[numberOfsong];
17. player[0] = minim.loadFile("sample_1.WAV");
18. player[1] = minim.loadFile("sample_2.WAV");
19. 
    
20. }
21. 
    
22. void draw()
23. {
24. background(0);
25. 
    
26. }
27. void keyPressed()
28. {
29.   switch (key)
30.   {
31.     case 'e':
32. 
    
33.     if ( player[currPlayer].isPlaying() )  // if any song is playing 
34.     {
35.       player[currPlayer].shiftGain(0, -50, 2000); // fade out of the playing song
36.       currPlayer = 0;                                          // update the integer
37.       player[currPlayer].rewind();                      // rewind from the beginning of the song
38.       player[currPlayer].setGain(0);                  // set the gain of the next song
39.       player[currPlayer].play();                        // play the next song
40.       player[currPlayer].shiftGain(-50,0, 2000);      // Fade in of the next song
41.     }
42.     else                                                             // no song is playing
43.     {
44.       currPlayer = 0;                                          // update the integer
45.       player[currPlayer].rewind();                      // rewind from the beginning of the song
46.       player[currPlayer].setGain(0);                   // set the gain of the next song
47.       player[currPlayer].play();                          // play the  song
48.       player[currPlayer].shiftGain(-50,0, 2000);   // Fade in of the song    
49.     }
50.     break;
51.     case 'r':
52.        if ( player[currPlayer].isPlaying() )
53.     {
54.       println("crossfade");
55.       player[currPlayer].shiftGain(0, -50, 2000);
56.       currPlayer = 1;
57.       player[currPlayer].rewind();
58.       player[currPlayer].setGain(0);
59.       player[currPlayer].play();
60.       player[currPlayer].shiftGain(-50,0, 1000);
61.     }
62.     else 
63.     {
64.       currPlayer = 1;
65.       player[currPlayer].rewind();
66.       player[currPlayer].setGain(0);
67.       player[currPlayer].play();
68.       player[currPlayer].shiftGain(-50,0, 500);
69.     }
70.     break;
71.   }
72. }
73. void stop()
74. {
75. player[0].close();
76. player[1].close();
77. minim.stop();
78. 
    
79. super.stop();
80. }