php man page for set_volume

set_volume(3alleg4)						  Allegro manual					       set_volume(3alleg4)

NAME
       set_volume - Alters the global sound output volume. Allegro game programming library.

SYNOPSIS
       #include <allegro.h>

       void set_volume(int digi_volume, int midi_volume);

DESCRIPTION
       Alters  the  global  sound  output volume. Specify volumes for both digital samples and MIDI playback, as integers from 0 to 255, or pass a
       negative value to leave one of the settings unchanged. Values bigger than 255 will be reduced to 255. This routine will not alter the  vol-
       ume of the hardware mixer if it exists (i.e. only your application will be affected).

SEE ALSO
       install_sound(3alleg4), set_hardware_volume(3alleg4)

Allegro 							   version 4.4.2					       set_volume(3alleg4)