Sound init routines
Allegro allows you to use the sound hardware in two ways: automatic, or
manual. Usually you should try the automatic version first. This means
calling install_sound() with the autodetection parameters and using the rest
of the sound functions to play samples or music. In this situation, Allegro
will handle the sound devices and mix the samples and/or music the best way
it can.
However, sound hardware has a limitation on the number of samples it may
play all at the same time (from now on, called hardware voices). When you
exceed this limit, Allegro will cut off one of the samples being played and
reproduce the new one. Depending on the type of sounds you are playing, how
many of them you need at the same time and their nature (e.g: vital audio
feedback to the user or useless "ping" when some shrapnel hits a rock in the
scenary) you will want to specify more carefully how hardware voices are
reserved and which samples have priority over others.
The hardware voice reservation phase has to be done before the call to
install_sound(), since it directly affects how Allegro talks to the sound
drivers.
