man voice_ramp_volume () - Starts a volume ramp for a voice. Allegro game programming library.
NAME
voice_ramp_volume - Starts a volume ramp for a voice. Allegro game programming library.
SYNOPSIS
#include <allegro.h>
void voice_ramp_volume(int voice, int time, int endvol);
DESCRIPTION
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.