<s>
Multimedia	B-Device
Class	I-Device
Scheduler	I-Device
Service	I-Device
(	O
MMCSS	B-Device
)	O
is	O
a	O
Windows	O
service	O
that	O
allows	O
multimedia	O
applications	O
to	O
get	O
prioritized	O
access	O
to	O
CPU	O
for	O
time-sensitive	O
processing	O
(	O
such	O
as	O
multimedia	O
applications	O
)	O
as	O
well	O
as	O
prioritized	O
disc	O
access	O
to	O
ensure	O
that	O
the	O
process	O
is	O
not	O
starved	O
of	O
data	O
to	O
process	O
.	O
</s>
<s>
The	O
MMCSS	B-Device
service	O
monitors	O
the	O
CPU	O
load	O
and	O
dynamically	O
adjusts	O
priority	O
so	O
that	O
the	O
application	O
can	O
use	O
as	O
much	O
CPU	O
time	O
as	O
possible	O
without	O
denying	O
CPU	O
to	O
lower	O
priority	O
applications	O
.	O
</s>
<s>
MMCSS	B-Device
uses	O
heuristics	O
to	O
determine	O
the	O
relative	O
priority	O
required	O
for	O
the	O
task	O
the	O
thread	O
is	O
performing	O
and	O
dynamically	O
adjusts	O
priority	O
based	O
on	O
that	O
.	O
</s>
<s>
A	O
thread	O
must	O
invoke	O
MMCSS	B-Device
explicitly	O
to	O
use	O
its	O
services	O
by	O
calling	O
the	O
AvSetMmMaxThreadCharacteristics( )	O
or	O
AvSetMmThreadCharacteristics( )	O
APIs	B-General_Concept
.	O
</s>
<s>
MMCSS	B-Device
is	O
used	O
by	O
the	O
multimedia	O
applications	O
in	O
Windows	B-Application
Vista	I-Application
,	O
including	O
Windows	B-Device
Media	I-Device
Player	I-Device
and	O
Windows	B-Device
Media	I-Device
Center	I-Device
to	O
provide	O
glitch-free	O
audio	O
playback	O
.	O
</s>
<s>
In	O
response	O
to	O
this	O
,	O
Microsoft	O
has	O
included	O
a	O
configurable	O
option	O
in	O
Windows	B-Application
Vista	I-Application
Service	O
Pack	O
1	O
and	O
later	O
where	O
users	O
can	O
specify	O
the	O
network	O
throttling	O
index	O
value	O
for	O
the	O
Multimedia	O
Class	O
Scheduling	O
Service	O
so	O
that	O
network	O
performance	O
and	O
audio/video	O
playback	O
quality	O
can	O
be	O
balanced	O
according	O
to	O
how	O
users	O
configure	O
it	O
.	O
</s>
