Allegro library problem

I didn't want to clutter up ValleyBell's topic too much, so I decided to start a new topic. This relates to the problem LOst was talking about.

I'm using Allegro v4.4. DIGI_AUTODETECT works fine. DIGI_DIRECTX(0) does not. The DirectX option has heavy audio distortion. A quick audio analysis reveals why it sounds bad. Here's what "silence" looks like:



So everything that plays will get played on top of that. Can anyone explain this?

Code (Text):

1. #include <allegro.h>
2.  
3. AUDIOSTREAM *stream;
4. short *allegroStream;
5. volatile int timer = 0;
6. volatile int timerChanged = 0;
7. void TimerUpdate(void);
8. const int testFrequency = 48000;
9.  
10.  
11.  
12. void TimerUpdate(void)
13. {
14.     timer++;
15.     timerChanged = 1;
16. }
17. END_OF_FUNCTION(TimerUpdate);
18.  
19.  
20.  
21. int main()
22. {
23.     allegro_init();
24.     install_keyboard();
25.     install_timer();
26.     //install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, NULL);
27.     install_sound(DIGI_DIRECTX(0), MIDI_AUTODETECT, NULL);
28.  
29.     set_color_depth(32);
30.     set_gfx_mode(GFX_AUTODETECT_WINDOWED, 320, 240, 0, 0);
31.  
32.     LOCK_VARIABLE(timer);
33.     LOCK_FUNCTION(TimerUpdate);
34.     install_int_ex(&TimerUpdate, BPS_TO_TIMER(60));
35.     stream = play_audio_stream(testFrequency/60, 16, 1, testFrequency, 255, 128);
36.  
37.     while(!key[KEY_ESC])
38.     {
39.         while(timerChanged == 0);
40.         timerChanged = 0;
41.  
42.         allegroStream = (short*)get_audio_stream_buffer(stream);
43.         if(allegroStream){
44.             for(int I = 0 ; I < (testFrequency/60)*2 ; I++)
45.             {
46.                 allegroStream[I] = 0;
47.             }
48.             free_audio_stream_buffer(stream);
49.         }
50.     }
51.  
52.     remove_timer();
53.     stop_audio_stream(stream);
54.  
55.     return 0;
56. }
57. END_OF_MAIN();