<s>
PulseAudio	B-Library
is	O
a	O
network-capable	O
sound	B-Application
server	I-Application
program	O
distributed	O
via	O
the	O
freedesktop.org	B-Application
project	O
.	O
</s>
<s>
It	O
runs	O
mainly	O
on	O
Linux	B-Application
,	O
various	O
BSD	B-Operating_System
distributions	O
such	O
as	O
FreeBSD	B-Operating_System
and	O
OpenBSD	B-Operating_System
,	O
macOS	B-Application
,	O
as	O
well	O
as	O
Illumos	B-Application
distributions	O
and	O
the	O
Solaris	B-Application
operating	I-Application
system	I-Application
.	O
</s>
<s>
PulseAudio	B-Library
is	O
free	B-License
and	I-License
open-source	I-License
software	I-License
,	O
and	O
is	O
licensed	O
under	O
the	O
terms	O
of	O
the	O
LGPL-2.1-or-later	B-Application
.	O
</s>
<s>
It	O
was	O
created	O
in	O
2004	O
under	O
the	O
name	O
Polypaudio	B-Library
but	O
was	O
renamed	O
in	O
2006	O
to	O
PulseAudio	B-Library
.	O
</s>
<s>
PulseAudio	B-Library
has	O
since	O
been	O
succeeded	O
by	O
PipeWire	B-Application
,	O
which	O
provides	O
a	O
compatible	O
PulseAudio	B-Library
server	O
(	O
known	O
as	O
pipewire-pulse	O
)	O
,	O
and	O
PipeWire	B-Application
is	O
now	O
used	O
by	O
default	O
on	O
many	O
Linux	B-Application
distributions	O
,	O
including	O
Fedora	O
Linux	B-Application
,	O
Ubuntu	B-Operating_System
,	O
and	O
Debian	O
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
was	O
previously	O
supported	O
via	O
MinGW	B-Application
(	O
an	O
implementation	O
of	O
the	O
GNU	B-Operating_System
toolchain	O
,	O
which	O
includes	O
various	O
tools	O
such	O
as	O
GCC	B-Application
and	O
binutils	B-Application
)	O
.	O
</s>
<s>
In	O
broad	O
terms	O
ALSA	B-Application
is	O
a	O
kernel	O
subsystem	O
that	O
provides	O
the	O
sound	O
hardware	O
driver	O
,	O
and	O
PulseAudio	B-Library
is	O
the	O
interface	O
engine	O
between	O
applications	O
and	O
ALSA	B-Application
.	O
</s>
<s>
However	O
,	O
its	O
use	O
is	O
not	O
mandatory	O
and	O
audio	O
can	O
still	O
be	O
played	O
and	O
mixed	O
together	O
without	O
PulseAudio	B-Library
.	O
</s>
<s>
PulseAudio	B-Library
acts	O
as	O
a	O
sound	B-Application
server	I-Application
,	O
where	O
a	O
background	O
process	O
accepting	O
sound	O
input	O
from	O
one	O
or	O
more	O
sources	O
(	O
processes	O
,	O
capture	O
devices	O
,	O
etc	O
.	O
)	O
</s>
<s>
The	O
background	O
process	O
then	O
redirects	O
these	O
sound	O
sources	O
to	O
one	O
or	O
more	O
sinks	O
(	O
sound	B-Device
cards	I-Device
,	O
remote	O
network	O
PulseAudio	B-Library
servers	O
,	O
or	O
other	O
processes	O
)	O
.	O
</s>
<s>
One	O
of	O
the	O
goals	O
of	O
PulseAudio	B-Library
is	O
to	O
reroute	O
all	O
sound	O
streams	O
through	O
it	O
,	O
including	O
those	O
from	O
processes	O
that	O
attempt	O
to	O
directly	O
access	O
the	O
hardware	O
(	O
like	O
legacy	O
OSS	B-Library
applications	O
)	O
.	O
</s>
<s>
PulseAudio	B-Library
achieves	O
this	O
by	O
providing	O
adapters	O
to	O
applications	O
using	O
other	O
audio	O
systems	O
,	O
like	O
aRts	O
and	O
ESD	B-Language
.	O
</s>
<s>
In	O
a	O
typical	O
installation	O
scenario	O
under	O
Linux	B-Application
,	O
the	O
user	O
configures	O
ALSA	B-Application
to	O
use	O
a	O
virtual	O
device	O
provided	O
by	O
PulseAudio	B-Library
.	O
</s>
<s>
Thus	O
,	O
applications	O
using	O
ALSA	B-Application
will	O
output	O
sound	O
to	O
PulseAudio	B-Library
,	O
which	O
then	O
uses	O
ALSA	B-Application
itself	O
to	O
access	O
the	O
real	O
sound	B-Device
card	I-Device
.	O
</s>
<s>
PulseAudio	B-Library
also	O
provides	O
its	O
own	O
native	O
interface	O
to	O
applications	O
that	O
want	O
to	O
support	O
PulseAudio	B-Library
directly	O
,	O
as	O
well	O
as	O
a	O
legacy	O
interface	O
for	O
ESD	B-Language
applications	O
,	O
making	O
it	O
suitable	O
as	O
a	O
drop-in	O
replacement	O
for	O
ESD	B-Language
.	O
</s>
<s>
For	O
OSS	B-Library
applications	O
,	O
PulseAudio	B-Library
provides	O
the	O
padsp	O
utility	O
,	O
which	O
replaces	O
device	O
files	O
such	O
as	O
/dev/dsp	B-Library
,	O
tricking	O
the	O
applications	O
into	O
believing	O
that	O
they	O
have	O
exclusive	O
control	O
over	O
the	O
sound	B-Device
card	I-Device
.	O
</s>
<s>
In	O
reality	O
,	O
their	O
output	O
is	O
rerouted	O
through	O
PulseAudio	B-Library
.	O
</s>
<s>
libcanberra	O
is	O
an	O
abstract	O
API	O
for	O
desktop	O
event	O
sounds	O
and	O
a	O
total	O
replacement	O
for	O
the	O
"	O
PulseAudio	B-Library
sample	O
cache	O
API	O
"	O
:	O
</s>
<s>
Interfaces	O
with	O
ALSA	B-Application
through	O
libasound	O
.	O
</s>
<s>
Has	O
a	O
back-end	O
to	O
PulseAudio	B-Library
.	O
</s>
<s>
libSydney	O
is	O
a	O
total	O
replacement	O
for	O
the	O
"	O
PulseAudio	B-Library
streaming	O
API	O
"	O
,	O
and	O
plans	O
have	O
been	O
made	O
for	O
libSydney	O
to	O
eventually	O
become	O
the	O
only	O
audio	O
API	O
used	O
in	O
PulseAudio	B-Library
.	O
</s>
<s>
The	O
main	O
PulseAudio	B-Library
features	O
include	O
:	O
</s>
<s>
PulseAudio	B-Library
first	O
appeared	O
for	O
regular	O
users	O
in	O
Fedora	O
Linux	B-Application
,	O
starting	O
with	O
version	O
8	O
,	O
then	O
was	O
adopted	O
by	O
major	O
Linux	B-Application
distributions	O
such	O
as	O
Ubuntu	B-Operating_System
,	O
Debian	O
,	O
Mandriva	O
Linux	B-Application
,	O
and	O
openSUSE	B-Operating_System
.	O
</s>
<s>
There	O
is	O
support	O
for	O
PulseAudio	B-Library
in	O
the	O
GNOME	B-Application
project	O
,	O
and	O
also	O
in	O
KDE	B-Application
,	O
as	O
it	O
is	O
integrated	O
into	O
Plasma	O
Workspaces	O
,	O
adding	O
support	O
to	O
Phonon	B-Language
(	O
the	O
KDE	B-Application
multimedia	O
framework	O
)	O
and	O
KMix	O
(	O
the	O
integrated	O
mixer	O
application	O
)	O
as	O
well	O
as	O
a	O
"	O
Speaker	O
Setup	O
"	O
GUI	O
to	O
aid	O
the	O
configuration	O
of	O
multi-channel	O
speakers	O
.	O
</s>
<s>
PulseAudio	B-Library
is	O
also	O
available	O
in	O
the	O
Illumos	B-Application
distribution	O
OpenIndiana	B-Application
,	O
and	O
enabled	O
by	O
default	O
in	O
its	O
MATE	B-Language
desktop	I-Language
environment	O
.	O
</s>
<s>
Various	O
Linux-based	O
mobile	O
devices	O
,	O
including	O
Nokia	B-Application
N900	I-Application
,	O
Nokia	B-Operating_System
N9	I-Operating_System
and	O
the	O
Palm	B-Application
Pre	I-Application
use	O
PulseAudio	B-Library
.	O
</s>
<s>
Tizen	B-Application
,	O
an	O
open-source	O
mobile	O
operating	B-General_Concept
system	I-General_Concept
,	O
which	O
is	O
a	O
project	O
of	O
the	B-Operating_System
Linux	I-Operating_System
Foundation	I-Operating_System
and	O
is	O
governed	O
by	O
a	O
Technical	O
Steering	O
Group	O
(	O
TSG	O
)	O
composed	O
of	O
Intel	O
and	O
Samsung	B-Application
,	O
uses	O
PulseAudio	B-Library
.	O
</s>
<s>
The	O
PortAudio	B-Language
API	O
was	O
incompatible	O
with	O
PulseAudio	B-Library
's	O
design	O
and	O
needed	O
to	O
be	O
modified	O
.	O
</s>
<s>
Almost	O
all	O
packages	O
using	O
OSS	B-Library
and	O
many	O
of	O
the	O
packages	O
using	O
ALSA	B-Application
needed	O
to	O
be	O
modified	O
to	O
support	O
PulseAudio	B-Library
.	O
</s>
<s>
Further	O
development	O
of	O
the	O
glitch-free	O
audio	O
feature	O
required	O
a	O
complete	O
rewrite	O
of	O
the	O
PulseAudio	B-Library
core	O
,	O
and	O
also	O
changes	O
to	O
the	O
ALSA	B-Application
API	O
and	O
internals	O
were	O
needed	O
.	O
</s>
<s>
When	O
first	O
adopted	O
by	O
distributions	O
,	O
PulseAudio	B-Library
developer	O
Lennart	O
Poettering	O
(	O
also	O
the	O
creator	O
of	O
systemd	B-Application
)	O
described	O
it	O
as	O
"	O
the	O
software	O
that	O
currently	O
breaks	O
your	O
audio	O
"	O
.	O
</s>
<s>
Poettering	O
later	O
claimed	O
that	O
"	O
Ubuntu	B-Operating_System
did	O
n't	O
exactly	O
do	O
a	O
stellar	O
job	O
.	O
</s>
<s>
They	O
did	O
n't	O
do	O
their	O
homework	O
"	O
in	O
adopting	O
PulseAudio	B-Library
for	O
Ubuntu	B-Operating_System
"	O
Hardy	O
Heron	O
"	O
(	O
8.04	O
)	O
,	O
a	O
problem	O
that	O
was	O
improved	O
with	O
subsequent	O
Ubuntu	B-Operating_System
releases	O
.	O
</s>
<s>
However	O
,	O
in	O
October	O
2009	O
,	O
Poettering	O
reported	O
that	O
he	O
was	O
still	O
not	O
happy	O
with	O
Ubuntu	B-Operating_System
's	O
integration	O
of	O
PulseAudio	B-Library
.	O
</s>
<s>
Interaction	O
with	O
old	O
sound	O
components	O
by	O
particular	O
software	O
:	O
Certain	O
programs	O
,	O
such	O
as	O
Adobe	B-Operating_System
Flash	I-Operating_System
for	O
Linux	B-Application
,	O
caused	O
instability	O
in	O
PulseAudio	B-Library
.	O
</s>
<s>
Newer	O
implementations	O
of	O
Flash	O
plugins	O
do	O
not	O
require	O
the	O
conflicting	O
elements	O
,	O
and	O
as	O
a	O
result	O
Flash	O
and	O
PulseAudio	B-Library
are	O
now	O
compatible	O
.	O
</s>
<s>
Early	O
management	O
of	O
buffer	O
over/underruns	O
:	O
Earlier	O
versions	O
of	O
PulseAudio	B-Library
sometimes	O
started	O
to	O
distort	O
the	O
processed	O
audio	O
due	O
to	O
incorrect	O
handling	O
of	O
buffer	O
over/underruns	O
.	O
</s>
<s>
JACK	B-Application
is	O
a	O
sound	B-Application
server	I-Application
that	O
provides	O
real-time	O
,	O
low-latency	O
(	O
i.e.	O
</s>
<s>
5	O
milliseconds	O
or	O
less	O
)	O
audio	O
performance	O
and	O
,	O
since	O
JACK2	O
,	O
supports	O
efficient	O
load	O
balancing	O
by	O
utilizing	O
symmetric	B-Operating_System
multiprocessing	I-Operating_System
;	O
that	O
is	O
,	O
the	O
load	O
of	O
all	O
audio	O
clients	O
can	O
be	O
distributed	O
among	O
several	O
processors	O
.	O
</s>
<s>
JACK	B-Application
is	O
the	O
preferred	O
sound	B-Application
server	I-Application
for	O
professional	O
audio	O
applications	O
such	O
as	O
Ardour	B-Language
,	O
ReZound	O
,	O
and	O
LinuxSampler	B-Application
;	O
multiple	O
free	O
audio-production	O
distributions	O
use	O
it	O
as	O
the	O
default	O
audio	O
server	O
.	O
</s>
<s>
It	O
is	O
possible	O
for	O
JACK	B-Application
and	O
PulseAudio	B-Library
to	O
coexist	O
:	O
while	O
JACK	B-Application
is	O
running	O
,	O
PulseAudio	B-Library
can	O
automatically	O
connect	O
itself	O
as	O
a	O
JACK	B-Application
client	O
,	O
allowing	O
PulseAudio	B-Library
clients	O
to	O
make	O
and	O
record	O
sound	O
at	O
the	O
same	O
time	O
as	O
JACK	B-Application
clients	O
.	O
</s>
<s>
PipeWire	B-Application
is	O
an	O
audio	O
and	O
video	O
server	O
that	O
"	O
aims	O
to	O
support	O
the	O
use	O
cases	O
currently	O
handled	O
by	O
both	O
PulseAudio	B-Library
and	O
Jack	B-Application
"	O
.	O
</s>
<s>
Before	O
JACK	B-Application
and	O
PulseAudio	B-Library
,	O
sound	O
on	O
these	O
systems	O
was	O
managed	O
by	O
multi-purpose	O
integrated	O
audio	O
solutions	O
.	O
</s>
<s>
These	O
solutions	O
do	O
not	O
fully	O
cover	O
the	O
mixing	O
and	O
sound	O
streaming	O
process	O
,	O
but	O
they	O
are	O
still	O
used	O
by	O
JACK	B-Application
and	O
PulseAudio	B-Library
to	O
send	O
the	O
final	O
audio	O
stream	O
to	O
the	O
sound	B-Device
card	I-Device
.	O
</s>
<s>
ALSA	B-Application
provides	O
a	O
software	O
mixer	O
called	O
dmix	O
,	O
which	O
was	O
developed	O
prior	O
to	O
PulseAudio	B-Library
.	O
</s>
<s>
This	O
is	O
available	O
on	O
almost	O
all	O
Linux	B-Application
distributions	O
and	O
is	O
a	O
simpler	O
PCM	O
audio	O
mixing	O
solution	O
.	O
</s>
<s>
It	O
does	O
not	O
provide	O
the	O
advanced	O
features	O
(	O
such	O
as	O
timer-based	O
scheduling	O
and	O
network	O
audio	O
)	O
of	O
PulseAudio	B-Library
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
ALSA	B-Application
offers	O
,	O
when	O
combined	O
with	O
corresponding	O
sound	B-Device
cards	I-Device
and	O
software	O
,	O
low	O
latencies	O
.	O
</s>
<s>
OSS	B-Library
was	O
the	O
original	O
sound	O
system	O
used	O
in	O
Linux	B-Application
and	O
other	O
Unix	O
operating	B-General_Concept
systems	I-General_Concept
,	O
but	O
was	O
deprecated	O
after	O
the	O
2.5	O
Linux	B-Application
kernel	O
.	O
</s>
<s>
Proprietary	O
development	O
was	O
continued	O
by	O
4Front	O
Technologies	O
,	O
who	O
in	O
July	O
2007	O
released	O
sources	O
for	O
OSS	B-Library
under	O
CDDL-1.0	B-Application
for	O
OpenSolaris	B-Operating_System
and	O
under	O
GPL-2.0-only	B-License
for	O
Linux	B-Application
.	O
</s>
<s>
The	O
modern	O
implementation	O
,	O
Open	B-Library
Sound	I-Library
System	I-Library
v4	O
,	O
provides	O
software	O
mixing	O
,	O
resampling	O
,	O
and	O
changing	O
of	O
the	O
volume	O
on	O
a	O
per-application	O
basis	O
;	O
in	O
contrast	O
to	O
PulseAudio	B-Library
,	O
these	O
features	O
are	O
implemented	O
within	O
the	O
kernel	O
.	O
</s>
<s>
PulseAudio	B-Library
support	O
in	O
OpenIndiana	B-Application
and	O
other	O
illumos	B-Application
distributions	O
relies	O
on	O
the	O
in-kernel	O
OSS	B-Library
implementation	O
(	O
"	O
Boomer	O
"	O
)	O
.	O
</s>
