<s>
Core	B-Operating_System
Video	I-Operating_System
is	O
the	O
video	O
processing	O
model	O
employed	O
by	O
macOS	B-Application
.	O
</s>
<s>
Both	O
QuickTime	B-Application
X	I-Application
and	O
QuickTime	B-Application
7	I-Application
depend	O
on	O
Core	B-Operating_System
Video	I-Operating_System
.	O
</s>
<s>
Core	B-Operating_System
Video	I-Operating_System
provides	O
both	O
a	O
buffering	O
model	O
and	O
a	O
playback	O
synchronization	O
solution	O
within	O
its	O
processing	O
pipeline	O
.	O
</s>
<s>
A	O
video	O
source	O
provides	O
a	O
decompressed	O
data	O
stream	O
to	O
be	O
rendered	O
as	O
images	O
within	O
a	O
visual	O
context	O
in	O
Quartz	B-Operating_System
2D	I-Operating_System
.	O
</s>
<s>
Core	B-Operating_System
Video	I-Operating_System
can	O
be	O
thought	O
of	O
as	O
the	O
link	O
between	O
this	O
video	O
source	O
and	O
its	O
display	O
context	O
.	O
</s>
<s>
Rendered	O
images	O
can	O
be	O
further	O
processed	O
by	O
Core	B-Operating_System
Image	I-Operating_System
before	O
being	O
composed	O
into	O
a	O
final	O
scene	O
with	O
Quartz	O
Compositor	O
.	O
</s>
<s>
As	O
part	O
of	O
the	O
composition	O
process	O
,	O
Core	B-Operating_System
Video	I-Operating_System
maintains	O
a	O
frame	O
buffer	O
,	O
keeping	O
a	O
pool	O
of	O
rendered	O
,	O
composed	O
frames	O
ready	O
for	O
playback	O
.	O
</s>
<s>
To	O
ensure	O
smooth	O
playback	O
,	O
Core	B-Operating_System
Video	I-Operating_System
uses	O
a	O
high-priority	O
thread	O
to	O
maintain	O
its	O
frame	O
buffer	O
.	O
</s>
<s>
Because	O
QuickTime	B-Application
7	I-Application
employed	O
Core	B-Operating_System
Video	I-Operating_System
,	O
it	O
was	O
the	O
first	O
version	O
of	O
QuickTime	B-Application
to	O
implement	O
the	O
rendering	O
capability	O
of	O
Quartz	O
.	O
</s>
<s>
Previous	O
versions	O
of	O
QuickTime	B-Application
used	O
QuickDraw	B-Operating_System
for	O
rendering	O
.	O
</s>
<s>
Although	O
Core	B-Operating_System
Video	I-Operating_System
typically	O
interacts	O
with	O
QuickTime	B-Application
,	O
it	O
can	O
interact	O
with	O
any	O
video	O
source	O
.	O
</s>
<s>
Core	B-Operating_System
Video	I-Operating_System
benefits	O
from	O
graphics	O
processor	O
(	O
GPU	O
)	O
rendering	O
and	O
composition	O
provided	O
by	O
Quartz	O
GL	O
,	O
Core	B-Operating_System
Image	I-Operating_System
,	O
and	O
Quartz	O
Extreme	O
,	O
since	O
final	O
playback	O
is	O
composed	O
on	O
an	O
OpenGL	O
surface	O
.	O
</s>
<s>
Although	O
Core	B-Operating_System
Video	I-Operating_System
was	O
introduced	O
with	O
the	O
release	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
v10.4	I-Application
,	O
it	O
is	O
included	O
in	O
the	O
installation	O
of	O
QuickTime	B-Application
7	I-Application
on	O
Mac	B-Application
OS	I-Application
X	O
;	O
thus	O
,	O
Core	B-Operating_System
Video	I-Operating_System
is	O
available	O
for	O
Mac	B-Application
OS	I-Application
X	O
10.3.9	O
with	O
QuickTime	B-Application
7	I-Application
installed	O
as	O
well	O
.	O
</s>
<s>
In	O
Mac	B-Application
OS	I-Application
X	I-Application
10.4	I-Application
,	O
Core	B-Operating_System
Video	I-Operating_System
is	O
implemented	O
as	O
part	O
of	O
the	O
QuartzCore	O
framework	O
;	O
in	O
Mac	B-Application
OS	I-Application
X	O
10.5	O
and	O
later	O
,	O
it	O
resides	O
in	O
its	O
own	O
framework	O
.	O
</s>
