<s>
aRts	O
(	O
which	O
stands	O
for	O
analog	O
real	B-General_Concept
time	I-General_Concept
synthesizer	O
)	O
is	O
an	O
audio	O
framework	O
that	O
is	O
no	O
longer	O
under	O
development	O
.	O
</s>
<s>
It	O
was	O
best	O
known	O
for	O
previously	O
being	O
used	O
in	O
K	B-Language
Desktop	I-Language
Environment	I-Language
2	I-Language
and	O
3	B-Application
to	O
simulate	O
an	O
analog	O
synthesizer	O
.	O
</s>
<s>
A	O
key	O
component	O
of	O
aRts	O
was	O
the	O
sound	B-Application
server	I-Application
which	O
mixes	O
several	O
sound	O
streams	O
in	O
real	B-General_Concept
time	I-General_Concept
.	O
</s>
<s>
The	O
sound	B-Application
server	I-Application
,	O
called	O
artsd	B-Language
(	O
d	O
for	O
daemon	B-Operating_System
)	O
,	O
was	O
also	O
utilized	O
as	O
the	O
standard	O
sound	B-Application
server	I-Application
for	O
K	B-Language
Desktop	I-Language
Environment	I-Language
2	I-Language
–	O
3	B-Application
.	O
</s>
<s>
However	O
,	O
the	O
sound	B-Application
server	I-Application
was	O
not	O
dependent	O
on	O
K	B-Application
Desktop	I-Application
Environment	I-Application
and	O
can	O
be	O
used	O
in	O
other	O
projects	O
.	O
</s>
<s>
It	O
was	O
a	O
direct	O
competitor	O
to	O
PulseAudio	B-Library
,	O
another	O
sound	B-Application
server	I-Application
,	O
and	O
an	O
indirect	O
competitor	O
to	O
the	O
Enlightened	B-Language
Sound	I-Language
Daemon	I-Language
(	O
ESD	O
)	O
.	O
</s>
<s>
It	O
is	O
now	O
common	O
to	O
use	O
PulseAudio	B-Library
instead	O
of	O
artsd	B-Language
.	O
</s>
<s>
The	O
aRts	O
platform	B-Device
also	O
includes	O
aRts	B-Language
Builder	I-Language
—	O
an	O
application	B-Application
for	O
building	O
custom	O
layouts	O
and	O
configurations	O
for	O
audio	O
mixers	O
,	O
sequencers	O
,	O
synthesizers	O
and	O
other	O
audio	O
schema	B-Application
via	O
a	O
user-friendly	O
graphical	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
aRts	O
is	O
free	B-Application
software	I-Application
,	O
distributed	O
under	O
the	O
terms	O
of	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
.	O
</s>
<s>
In	O
KDE	B-Language
Software	I-Language
Compilation	I-Language
4	I-Language
developers	O
chose	O
to	O
replace	O
aRts	O
with	O
a	O
new	O
multimedia	O
API	O
known	O
as	O
Phonon	B-Language
.	O
</s>
<s>
Phonon	B-Language
provides	O
a	O
common	O
interface	O
on	O
top	O
of	O
other	O
systems	O
,	O
usually	O
VLC	B-Application
media	I-Application
player	I-Application
or	O
GStreamer	B-Language
,	O
to	O
avoid	O
being	O
dependent	O
on	O
a	O
single	O
multimedia	O
framework	O
.	O
</s>
