Starts a volume ramp for a voice. allegro game programming library.
#include <allegro.h>
void voice_ramp_volume(int voice, int time, int endvol);
Starts a volume ramp (crescendo or diminuendo) from the current volume to the specified ending volume, lasting for time milliseconds. The volume is a value in the range 0-255.
voice_set_volume(3alleg4)