C and SDL for audio - Crossfade doesnt work

Hi,

i am currently doing a crossfade system with SDL but i got a problem with the fadeout.

This is my code for the callback function

Code:

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int i, j; 

/* Loop that selects the audio slots which are running */ 

 for (i = 0; i < NBR_OF_AUDIO_SLOTS; i++)

{     

      if (soundplayer_isplaying(&audio_slots[i]))
              {       
                soundplayer * player = &audio_slots[i];
                sound * toplay = player->played_sound;
 
                /* Number of samples */       
                Uint32 nbSamples = len/sizeof(Sint16);         
                for (j = 0; j < nbSamples; j++)
                    {           
                    Sint16 sound1 = ((Sint16 *)stream)[j];       

                      /* Current sample or 0 if the sound is finished */         
                      Sint16 sound2 = (player->pos < toplay->length) ?  (*(Sint16 *)(toplay->data + player->pos)) : 0;     

                      /* X is the number of sample for the crossfade, equal to 0 everytime i run a new sound */     

                      if (x < 8191 )     
                      {           

                      /* Cosinus function for the crossfade */     
                      double fadeout =  cos( (x * M_PI) / ((nbSamples-1) *2)  );     
                      double fadein = 1 -  cos( (x * M_PI) / ((nbSamples-1) *2)  );           

                      /* Fadeout application */     

                      Uint8 volume = (double)((double)global_volume * fadeout);     
                      sound1 = sample_volume(sound1, volume);           

                      /* Fade in application*/     

                      volume = (double)((double)global_volume * fadein);     
                      sound2 = sample_volume(sound2, volume);             


                      /* Mix the 2 sounds  */       
                      sound2 = sample_mix(sound2, sound1);       

                      x++;     
                      }     
                    else      {     
                                /* Crossfade is over, keep only the new sound */         

                                sound2 = sample_volume(sound2, 255);       
                                }           

                      /* Add to the audio buffer */         
                      ((Sint16 *)stream)[j] = sample;           
                      player->pos += sizeof(Sint16);         
                      }     

                      /* Update */       
                      soundplayer_update(player);     
}  }    }

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So when i run 2 sounds one after the other, the first sound stop suddently and the second one fades in. I dont understand why the fadeout doesnt work :S