<s>
DirectShow	B-Library
(	O
sometimes	O
abbreviated	O
as	O
DS	O
or	O
DShow	B-Library
)	O
,	O
codename	O
Quartz	O
,	O
is	O
a	O
multimedia	B-Library
framework	I-Library
and	O
API	B-Application
produced	O
by	O
Microsoft	O
for	O
software	B-Application
developers	I-Application
to	O
perform	O
various	O
operations	O
with	O
media	O
files	O
or	O
streams	O
.	O
</s>
<s>
It	O
is	O
the	O
replacement	O
for	O
Microsoft	O
's	O
earlier	O
Video	B-Device
for	I-Device
Windows	I-Device
technology	O
.	O
</s>
<s>
Based	O
on	O
the	O
Microsoft	B-Application
Windows	I-Application
Component	B-Application
Object	I-Application
Model	I-Application
(	O
COM	O
)	O
framework	O
,	O
DirectShow	B-Library
provides	O
a	O
common	O
interface	O
for	O
media	O
across	O
various	O
programming	O
languages	O
,	O
and	O
is	O
an	O
extensible	O
,	O
filter-based	O
framework	O
that	O
can	O
render	O
or	O
record	O
media	O
files	O
on	O
demand	O
at	O
the	O
request	O
of	O
the	O
user	O
or	O
developer	B-Application
.	O
</s>
<s>
The	O
DirectShow	B-Library
development	O
tools	O
and	O
documentation	O
were	O
originally	O
distributed	O
as	O
part	O
of	O
the	O
DirectX	B-Application
SDK	B-Application
.	O
</s>
<s>
Currently	O
,	O
they	O
are	O
distributed	O
as	O
part	O
of	O
the	O
Windows	B-Application
SDK	I-Application
(	O
formerly	O
known	O
as	O
the	O
Platform	B-Application
SDK	I-Application
)	O
.	O
</s>
<s>
Microsoft	O
plans	O
to	O
completely	O
replace	O
DirectShow	B-Library
gradually	O
with	O
Media	B-Device
Foundation	I-Device
in	O
future	O
Windows	O
versions	O
.	O
</s>
<s>
Microsoft	O
's	O
Becky	O
Weiss	O
confirmed	O
in	O
2006	O
that	O
"	O
you	O
'll	O
notice	O
that	O
working	O
with	O
the	O
Media	B-Device
Foundation	I-Device
requires	O
you	O
to	O
work	O
at	O
a	O
slightly	O
lower	O
level	O
than	O
working	O
with	O
DirectShow	B-Library
would	O
have	O
.	O
</s>
<s>
And	O
there	O
are	O
still	O
DirectShow	B-Library
features	O
that	O
are	O
n't	O
(	O
yet	O
)	O
in	O
Media	B-Device
Foundation	I-Device
"	O
.	O
</s>
<s>
As	O
described	O
in	O
the	O
Media	B-Device
Foundation	I-Device
article	O
,	O
Windows	B-Application
Vista	I-Application
and	O
Windows	B-Device
7	I-Device
applications	O
use	O
Media	B-Device
Foundation	I-Device
instead	O
of	O
DirectShow	B-Library
for	O
several	O
media	O
related	O
tasks	O
.	O
</s>
<s>
The	O
direct	O
predecessor	O
of	O
DirectShow	B-Library
,	O
ActiveMovie	B-Application
(	O
codenamed	O
Quartz	O
)	O
,	O
was	O
designed	O
to	O
provide	O
MPEG-1	B-Algorithm
support	O
for	O
Windows	O
.	O
</s>
<s>
It	O
was	O
also	O
intended	O
as	O
a	O
future	O
replacement	O
for	O
media	O
processing	O
frameworks	O
like	O
Video	B-Device
for	I-Device
Windows	I-Device
and	O
the	O
Media	B-Device
Control	I-Device
Interface	I-Device
,	O
which	O
had	O
never	O
been	O
fully	O
ported	O
to	O
a	O
32-bit	O
environment	O
and	O
did	O
not	O
utilize	O
COM	O
.	O
</s>
<s>
The	O
development	O
team	O
used	O
a	O
pre-existing	O
modular	O
digital-media-processor	O
project	O
codenamed	O
"	O
Clockwork	O
"	O
as	O
a	O
basis	O
for	O
DirectShow	B-Library
.	O
</s>
<s>
The	O
project	O
was	O
initially	O
named	O
"	O
ActiveMovie	B-Application
"	O
,	O
and	O
was	O
released	O
in	O
May	O
1996	O
,	O
bundled	O
with	O
the	O
beta	O
version	O
of	O
Internet	B-Protocol
Explorer	I-Protocol
3.0	I-Protocol
.	O
</s>
<s>
In	O
March	O
1997	O
,	O
Microsoft	O
announced	O
that	O
ActiveMovie	B-Application
would	O
become	O
part	O
of	O
the	O
DirectX	B-Application
5	O
suite	O
of	O
technologies	O
,	O
and	O
around	O
July	O
started	O
referring	O
to	O
it	O
as	O
DirectShow	B-Library
,	O
reflecting	O
Microsoft	O
's	O
efforts	O
at	O
the	O
time	O
to	O
consolidate	O
technologies	O
that	O
worked	O
directly	O
with	O
hardware	O
under	O
a	O
common	O
naming	O
scheme	O
.	O
</s>
<s>
DirectShow	B-Library
became	O
a	O
standard	O
component	O
of	O
all	O
Windows	B-Application
operating	I-Application
systems	I-Application
starting	O
with	O
Windows	B-Device
98	I-Device
;	O
however	O
it	O
is	O
available	O
on	O
Windows	B-Application
95	I-Application
by	O
installing	O
the	O
latest	O
available	O
DirectX	B-Application
redistributable	O
.	O
</s>
<s>
In	O
DirectX	B-Application
version	O
8.0	O
,	O
DirectShow	B-Library
became	O
part	O
of	O
the	O
core	O
DirectX	B-Application
SDK	B-Application
along	O
with	O
other	O
DirectX	B-Application
APIs	B-Application
.	O
</s>
<s>
In	O
October	O
2004	O
,	O
DirectShow	B-Library
was	O
removed	O
from	O
the	O
main	O
DirectX	B-Application
distribution	O
and	O
relocated	O
to	O
the	O
DirectX	B-Application
Extras	O
download	O
.	O
</s>
<s>
In	O
April	O
2005	O
,	O
DirectShow	B-Library
was	O
removed	O
entirely	O
from	O
DirectX	B-Application
and	O
moved	O
to	O
the	O
Windows	B-Application
SDK	I-Application
starting	O
with	O
the	O
Windows	O
Server	O
2003	O
SP1	O
version	O
of	O
the	O
SDK	B-Application
.	O
</s>
<s>
The	O
DirectX	B-Application
SDK	B-Application
was	O
,	O
however	O
,	O
still	O
required	O
to	O
build	O
some	O
of	O
the	O
DirectShow	B-Library
samples	O
.	O
</s>
<s>
Since	O
November	O
2007	O
,	O
DirectShow	B-Library
APIs	B-Application
are	O
part	O
of	O
the	O
Windows	B-Application
SDK	I-Application
.	O
</s>
<s>
It	O
includes	O
several	O
new	O
enhancements	O
,	O
codecs	O
and	O
filter	B-Application
updates	O
such	O
as	O
the	O
Enhanced	O
Video	O
Renderer	O
(	O
EVR	O
)	O
and	O
DXVA	B-General_Concept
2.0	I-General_Concept
(	O
DirectX	B-General_Concept
Video	I-General_Concept
Acceleration	I-General_Concept
)	O
.	O
</s>
<s>
DirectShow	B-Library
divides	O
a	O
complex	O
multimedia	O
task	O
(	O
e.g.	O
</s>
<s>
video	O
playback	O
)	O
into	O
a	O
sequence	O
of	O
fundamental	O
processing	O
steps	O
known	O
as	O
filters	B-Application
.	O
</s>
<s>
Each	O
filterwhich	O
represents	O
one	O
stage	O
in	O
the	O
processing	O
of	O
the	O
datahas	O
input	O
and/or	O
output	O
pins	O
that	O
may	O
be	O
used	O
to	O
connect	O
the	O
filter	B-Application
to	O
other	O
filters	B-Application
.	O
</s>
<s>
The	O
generic	O
nature	O
of	O
this	O
connection	O
mechanism	O
enables	O
filters	B-Application
to	O
be	O
connected	O
in	O
various	O
ways	O
so	O
as	O
to	O
implement	O
different	O
complex	O
functions	O
.	O
</s>
<s>
To	O
implement	O
a	O
specific	O
complex	O
task	O
,	O
a	O
developer	B-Application
must	O
first	O
build	O
a	O
filter	B-Library
graph	I-Library
by	O
creating	O
instances	O
of	O
the	O
required	O
filters	B-Application
,	O
and	O
then	O
connecting	O
the	O
filters	B-Application
together	O
.	O
</s>
<s>
There	O
are	O
three	O
main	O
types	O
of	O
filters	B-Application
:	O
</s>
<s>
Source	O
filters	B-Application
These	O
provide	O
the	O
source	O
streams	O
of	O
data	O
.	O
</s>
<s>
Transform	O
filters	B-Application
These	O
transform	O
data	O
that	O
is	O
provided	O
from	O
other	O
filter	B-Application
's	O
output	O
.	O
</s>
<s>
Renderer	O
filters	B-Application
These	O
render	O
the	O
data	O
.	O
</s>
<s>
During	O
the	O
rendering	O
process	O
,	O
the	O
filter	B-Library
graph	I-Library
searches	O
the	O
Windows	B-Protocol
Registry	I-Protocol
for	O
registered	O
filters	B-Application
and	O
builds	O
its	O
graph	O
of	O
filters	B-Application
based	O
on	O
the	O
locations	O
provided	O
.	O
</s>
<s>
After	O
this	O
,	O
it	O
connects	O
the	O
filters	B-Application
together	O
,	O
and	O
,	O
at	O
the	O
developer	B-Application
's	O
request	O
,	O
executes	O
(	O
i.e.	O
,	O
plays	O
,	O
pauses	O
,	O
etc	O
.	O
)	O
</s>
<s>
DirectShow	B-Library
filter	B-Library
graphs	I-Library
are	O
widely	O
used	O
in	O
video	O
playback	O
(	O
in	O
which	O
the	O
filters	B-Application
implement	O
functions	O
such	O
as	O
file	O
parsing	O
,	O
video	O
and	O
audio	O
demultiplexing	O
,	O
decompressing	O
and	O
rendering	O
)	O
as	O
well	O
as	O
for	O
video	O
and	O
audio	O
recording	O
,	O
editing	O
,	O
encoding	O
,	O
transcoding	O
or	O
network	O
transmission	O
of	O
media	O
.	O
</s>
<s>
Interactive	O
tasks	O
such	O
as	O
DVD	O
navigation	O
may	O
also	O
be	O
controlled	O
by	O
DirectShow	B-Library
.	O
</s>
<s>
In	O
the	O
above	O
example	O
,	O
from	O
left	O
to	O
right	O
,	O
the	O
graph	O
contains	O
a	O
source	O
filter	B-Application
to	O
read	O
an	O
MP3	B-Application
file	I-Application
,	O
stream	B-Architecture
splitter	O
and	O
decoder	O
filters	B-Application
to	O
parse	O
and	O
decode	O
the	O
audio	O
,	O
and	O
a	O
rendering	O
filter	B-Application
to	O
play	O
the	O
raw	O
audio	O
samples	O
.	O
</s>
<s>
Each	O
filter	B-Application
has	O
one	O
or	O
more	O
pins	O
that	O
can	O
be	O
used	O
to	O
connect	O
that	O
filter	B-Application
to	O
other	O
filters	B-Application
.	O
</s>
<s>
Every	O
pin	O
functions	O
either	O
as	O
an	O
output	O
or	O
input	O
source	O
for	O
data	O
to	O
flow	O
from	O
one	O
filter	B-Application
to	O
another	O
.	O
</s>
<s>
Depending	O
on	O
the	O
filter	B-Application
,	O
data	O
is	O
either	O
"	O
pulled	O
"	O
from	O
an	O
input	O
pin	O
or	O
"	O
pushed	O
"	O
to	O
an	O
output	O
pin	O
in	O
order	O
to	O
transfer	O
data	O
between	O
filters	B-Application
.	O
</s>
<s>
Most	O
filters	B-Application
are	O
built	O
using	O
a	O
set	O
of	O
C++	O
classes	O
provided	O
in	O
the	O
DirectShow	B-Library
SDK	B-Application
,	O
called	O
the	O
DirectShow	B-Library
Base	O
Classes	O
.	O
</s>
<s>
These	O
handle	O
much	O
of	O
the	O
creation	O
,	O
registration	O
and	O
connection	O
logic	O
for	O
the	O
filter	B-Application
.	O
</s>
<s>
For	O
the	O
filter	B-Library
graph	I-Library
to	O
use	O
filters	B-Application
automatically	O
,	O
they	O
need	O
to	O
be	O
registered	O
in	O
a	O
separate	O
DirectShow	B-Library
registry	O
entry	O
as	O
well	O
as	O
being	O
registered	O
with	O
COM	O
.	O
</s>
<s>
This	O
registration	O
can	O
be	O
managed	O
by	O
the	O
DirectShow	B-Library
Base	O
Classes	O
.	O
</s>
<s>
However	O
,	O
if	O
the	O
application	O
adds	O
the	O
filters	B-Application
manually	O
,	O
they	O
do	O
not	O
need	O
to	O
be	O
registered	O
at	O
all	O
.	O
</s>
<s>
Starting	O
with	O
DirectShow	B-Library
8.0	O
,	O
dynamic	O
graph	O
building	O
,	O
dynamic	O
reconnection	O
,	O
and	O
filter	B-Application
chains	O
were	O
introduced	O
to	O
help	O
alter	O
the	O
graph	O
while	O
it	O
was	O
running	O
.	O
</s>
<s>
However	O
,	O
many	O
filter	B-Application
vendors	O
ignore	O
this	O
feature	O
,	O
making	O
graph	O
modification	O
problematic	O
after	O
a	O
graph	O
has	O
begun	O
processing	O
.	O
</s>
<s>
Although	O
DirectShow	B-Library
is	O
capable	O
of	O
dynamically	O
building	O
a	O
graph	O
to	O
render	O
a	O
given	O
media	O
type	O
,	O
in	O
certain	O
instances	O
it	O
is	O
difficult	O
for	O
developers	B-Application
to	O
rely	O
on	O
this	O
functionality	O
and	O
they	O
need	O
to	O
resort	O
to	O
manually	O
building	O
filter	B-Library
graphs	I-Library
if	O
the	O
resulting	O
filter	B-Library
graph	I-Library
is	O
variable	O
.	O
</s>
<s>
It	O
is	O
possible	O
for	O
filter	B-Library
graphs	I-Library
to	O
change	O
over	O
time	O
as	O
new	O
filters	B-Application
are	O
installed	O
on	O
the	O
computer	O
.	O
</s>
<s>
By	O
default	O
,	O
DirectShow	B-Library
includes	O
a	O
number	O
of	O
filters	B-Application
for	O
decoding	O
some	O
common	O
media	O
file	O
formats	O
such	O
as	O
MPEG-1	B-Algorithm
,	O
MP3	B-Application
,	O
Windows	B-Application
Media	I-Application
Audio	I-Application
,	O
Windows	B-Application
Media	I-Application
Video	I-Application
,	O
MIDI	O
,	O
media	O
containers	O
such	O
as	O
AVI	O
,	O
ASF	B-Application
,	O
WAV	O
,	O
some	O
splitters/demultiplexers	O
,	O
multiplexers	O
,	O
source	O
and	O
sink	B-Application
filters	B-Application
,	O
some	O
static	O
image	O
filters	B-Application
,	O
and	O
minimal	O
digital	O
rights	O
management	O
(	O
DRM	O
)	O
support	O
.	O
</s>
<s>
DirectShow	B-Library
's	O
standard	O
format	O
repertoire	O
can	O
be	O
easily	O
expanded	O
by	O
means	O
of	O
a	O
variety	O
of	O
filters	B-Application
,	O
enabling	O
DirectShow	B-Library
to	O
support	O
virtually	O
any	O
container	O
format	O
and	O
any	O
audio	O
or	O
video	O
codec	O
.	O
</s>
<s>
For	O
example	O
,	O
filters	B-Application
have	O
been	O
developed	O
for	O
Ogg	B-Algorithm
Vorbis	I-Algorithm
,	O
Musepack	B-Algorithm
,	O
and	O
AC3	O
,	O
and	O
some	O
codecs	O
such	O
as	O
MPEG-4	B-Algorithm
Advanced	I-Algorithm
Simple	I-Algorithm
Profile	I-Algorithm
,	O
AAC	B-Application
,	O
H.264	B-Application
,	O
Vorbis	B-Algorithm
and	O
containers	O
MOV	B-Application
,	O
MP4	O
are	O
available	O
from	O
3rd	O
parties	O
like	O
ffdshow	B-Language
,	O
K-Lite	B-Application
,	O
and	O
CCCP	B-Application
.	O
</s>
<s>
Incorporating	O
support	O
for	O
additional	O
codecs	O
such	O
as	O
these	O
can	O
involve	O
paying	O
the	O
licensing	O
fees	O
to	O
the	O
involved	O
codec	O
technology	O
developer	B-Application
or	O
patent	O
holder	O
.	O
</s>
<s>
Finally	O
,	O
there	O
are	O
"	O
bridge	O
"	O
filters	B-Application
that	O
simultaneously	O
support	O
multiple	O
formats	O
,	O
as	O
well	O
as	O
functions	O
like	O
stream	B-Architecture
multiplexing	O
,	O
by	O
exposing	O
the	O
functionality	O
of	O
underlying	O
multimedia	O
APIs	B-Application
such	O
as	O
VLC	B-Application
.	O
</s>
<s>
The	O
amount	O
of	O
work	O
required	O
to	O
implement	O
a	O
filter	B-Library
graph	I-Library
depends	O
on	O
several	O
factors	O
.	O
</s>
<s>
In	O
the	O
simplest	O
case	O
,	O
DirectShow	B-Library
can	O
create	O
a	O
filter	B-Library
graph	I-Library
automatically	O
from	O
a	O
source	O
such	O
as	O
a	O
file	O
or	O
URL	O
.	O
</s>
<s>
If	O
this	O
is	O
not	O
possible	O
,	O
the	O
developer	B-Application
may	O
be	O
able	O
to	O
manually	O
create	O
a	O
filter	B-Library
graph	I-Library
from	O
a	O
source	O
file	O
,	O
possibly	O
with	O
the	O
addition	O
of	O
a	O
custom	O
filter	B-Application
,	O
and	O
then	O
let	O
DirectShow	B-Library
complete	O
the	O
filter	B-Library
graph	I-Library
by	O
connecting	O
the	O
filters	B-Application
together	O
.	O
</s>
<s>
At	O
the	O
next	O
level	O
,	O
the	O
developer	B-Application
must	O
build	O
the	O
filter	B-Library
graph	I-Library
from	O
scratch	O
by	O
manually	O
adding	O
and	O
connecting	O
each	O
desired	O
filter	B-Application
.	O
</s>
<s>
Finally	O
,	O
in	O
cases	O
where	O
an	O
essential	O
filter	B-Application
is	O
unavailable	O
,	O
the	O
developer	B-Application
must	O
create	O
a	O
custom	O
filter	B-Application
before	O
a	O
filter	B-Library
graph	I-Library
can	O
be	O
built	O
.	O
</s>
<s>
Unlike	O
the	O
main	O
C	O
API	B-Application
of	O
QuickTime	B-Application
where	O
it	O
is	O
necessary	O
to	O
call	O
MoviesTask	O
in	O
a	O
loop	O
to	O
load	O
a	O
media	O
file	O
,	O
DirectShow	B-Library
handles	O
all	O
of	O
this	O
in	O
a	O
transparent	O
way	O
.	O
</s>
<s>
It	O
creates	O
several	O
background	O
threads	O
that	O
smoothly	O
play	O
the	O
requested	O
file	O
or	O
URL	O
without	O
much	O
work	O
required	O
from	O
the	O
programmer	B-Application
.	O
</s>
<s>
Also	O
in	O
contrast	O
to	O
QuickTime	B-Application
,	O
nothing	O
special	O
is	O
required	O
for	O
loading	O
a	O
URL	O
instead	O
of	O
a	O
local	O
file	O
on	O
diskDirectShow	O
's	O
filter	B-Library
graph	I-Library
abstracts	O
these	O
details	O
from	O
the	O
programmer	B-Application
,	O
although	O
recent	O
developments	O
in	O
QuickTime	B-Application
(	O
including	O
an	O
ActiveX	B-Application
control	I-Application
)	O
have	O
reduced	O
this	O
disparity	O
.	O
</s>
<s>
DirectShow	B-Library
Editing	O
Services	O
(	O
DES	O
)	O
,	O
introduced	O
in	O
DirectX	O
8.0/Windows	O
XP	O
is	O
an	O
API	B-Application
targeted	O
at	O
video	O
editing	O
tasks	O
and	O
built	O
on	O
top	O
of	O
the	O
core	O
DirectShow	B-Library
architecture	O
.	O
</s>
<s>
DirectShow	B-Library
Editing	O
Services	O
was	O
introduced	O
for	O
Microsoft	O
's	O
Windows	B-Application
Movie	I-Application
Maker	I-Application
.	O
</s>
<s>
It	O
includes	O
APIs	B-Application
for	O
timeline	O
and	O
switching	O
services	O
,	O
resizing	O
,	O
cropping	O
,	O
video	O
and	O
audio	O
effects	O
,	O
as	O
well	O
as	O
transitions	O
,	O
keying	O
,	O
automatic	O
frame	O
rate	O
and	O
sample	O
rate	O
conversion	O
and	O
such	O
other	O
features	O
which	O
are	O
used	O
in	O
non-linear	O
video	O
editing	O
allowing	O
creation	O
of	O
composite	O
media	O
out	O
of	O
a	O
number	O
of	O
source	O
audio	O
and	O
video	O
streams	O
.	O
</s>
<s>
DirectShow	B-Library
Editing	O
Services	O
allow	O
higher-level	O
run-time	O
compositing	O
,	O
seeking	O
support	O
,	O
and	O
graph	O
management	O
,	O
while	O
still	O
allowing	O
applications	O
to	O
access	O
lower-level	O
DirectShow	B-Library
functions	O
.	O
</s>
<s>
While	O
the	O
original	O
API	B-Application
is	O
in	O
C++	O
,	O
DirectShow	B-Library
Editing	O
Services	O
is	O
accessible	O
in	O
any	O
Microsoft	O
.NET	O
compatible	O
language	O
including	O
Microsoft	O
Visual	O
C#	O
and	O
Microsoft	O
Visual	B-Language
Basic	I-Language
by	O
using	O
a	O
third-party	O
code	O
library	O
called	O
"	O
DirectShowNet	O
Library	O
"	O
.	O
</s>
<s>
Alternatively	O
,	O
the	O
entire	O
DirectShow	B-Library
API	B-Application
,	O
including	O
DirectShow	B-Library
Editing	O
Services	O
,	O
can	O
be	O
accessed	O
from	O
Borland	B-Language
Delphi	I-Language
5	O
,	O
6	O
and	O
7	O
,	O
C++	B-Language
Builder	I-Language
6	O
,	O
and	O
from	O
later	O
versions	O
with	O
a	O
few	O
minor	O
modifications	O
,	O
using	O
a	O
third	O
party	O
software	O
library	O
called	O
"	O
DSPack	O
"	O
.	O
</s>
<s>
As	O
of	O
March	O
,	O
2012	O
(	O
and	O
,	O
apparently	O
as	O
early	O
as	O
2009	O
)	O
,	O
Microsoft	O
has	O
stated	O
that	O
the	O
DirectShow	B-Library
Editing	O
Services	O
"	O
API	B-Application
is	O
not	O
supported	O
and	O
may	O
be	O
altered	O
or	O
unavailable	O
in	O
the	O
future.	O
"	O
</s>
<s>
Originally	O
,	O
in	O
Windows	O
9x	O
,	O
DirectShow	B-Library
used	O
the	O
Video	O
Renderer	O
filter	B-Application
.	O
</s>
<s>
This	O
drew	O
the	O
images	O
using	O
DirectDraw	B-Device
3	O
,	O
but	O
could	O
also	O
fall	O
back	O
to	O
GDI	B-Operating_System
or	O
overlay	O
drawing	O
modes	O
in	O
some	O
circumstances	O
(	O
depending	O
upon	O
the	O
visibility	O
of	O
the	O
video	O
window	O
and	O
the	O
video	O
card	O
's	O
capabilities	O
)	O
.	O
</s>
<s>
Video	B-Device
for	I-Device
Windows	I-Device
had	O
been	O
plagued	O
with	O
deadlocks	B-Operating_System
caused	O
by	O
applications	O
 '	O
incorrect	O
handling	O
of	O
the	O
video	O
windows	O
,	O
so	O
in	O
early	O
DirectShow	B-Library
releases	O
,	O
the	O
handle	O
to	O
the	O
playback	O
window	O
was	O
hidden	O
from	O
applications	O
.	O
</s>
<s>
DirectShow	B-Library
6.0	O
,	O
released	O
as	O
part	O
of	O
DirectX	B-Application
Media	I-Application
introduced	O
the	O
Overlay	O
Mixer	O
renderer	O
designed	O
for	O
DVD	O
playback	O
and	O
broadcast	B-Operating_System
video	O
streams	O
with	O
closed	O
captioning	O
and	O
subtitles	O
.	O
</s>
<s>
The	O
Overlay	O
Mixer	O
uses	O
DirectDraw	B-Device
5	O
for	O
rendering	O
.	O
</s>
<s>
Overlay	O
Mixer	O
also	O
supports	O
Video	O
Port	O
Extensions	O
(	O
VPE	O
)	O
,	O
enabling	O
it	O
to	O
work	O
with	O
analog	O
TV	B-Device
tuners	I-Device
with	O
overlay	O
capability	O
(	O
sending	O
video	O
directly	O
to	O
a	O
video	O
card	O
via	O
an	O
analog	O
link	O
rather	O
than	O
via	O
the	O
PCI	B-Protocol
bus	I-Protocol
)	O
.	O
</s>
<s>
Overlay	O
Mixer	O
also	O
supports	O
DXVA	B-General_Concept
connections	O
.	O
</s>
<s>
Because	O
it	O
always	O
renders	O
in	O
overlay	O
,	O
full-screen	O
video	O
to	O
TV-out	B-Device
is	O
always	O
activated	O
.	O
</s>
<s>
Starting	O
with	O
Windows	B-Application
XP	I-Application
,	O
a	O
new	O
filter	B-Application
called	O
the	O
Video	B-Library
Mixing	I-Library
Renderer	I-Library
7	O
(	O
VMR-7	O
or	O
sometimes	O
just	O
referred	O
to	O
as	O
VMR	O
)	O
was	O
introduced	O
.	O
</s>
<s>
The	O
number	O
7	O
was	O
because	O
VMR-7	O
only	O
used	O
DirectDraw	B-Device
version	O
7	O
to	O
render	O
the	O
video	O
and	O
did	O
not	O
have	O
the	O
option	O
to	O
use	O
GDI	B-Operating_System
drawing	O
.	O
</s>
<s>
DirectX	B-Application
9	I-Application
introduced	O
VMR-9	O
,	O
which	O
is	O
included	O
in	O
Windows	B-Application
XP	I-Application
SP2	O
and	O
newer	O
.	O
</s>
<s>
This	O
version	O
uses	O
Direct3D	B-Application
9	O
instead	O
of	O
DirectDraw	B-Device
,	O
allowing	O
developers	B-Application
to	O
transform	O
video	O
images	O
using	O
the	O
Direct3D	B-Application
pixel	O
shaders	O
.	O
</s>
<s>
It	O
is	O
available	O
for	O
all	O
Windows	O
platforms	O
as	O
part	O
of	O
the	O
DirectX	B-Application
9	I-Application
redistributable	O
.	O
</s>
<s>
Windows	B-Application
Vista	I-Application
and	O
Windows	B-Device
7	I-Device
ship	O
with	O
a	O
new	O
renderer	O
,	O
available	O
as	O
both	O
a	O
Media	B-Device
Foundation	I-Device
component	O
and	O
a	O
DirectShow	B-Library
filter	B-Application
,	O
called	O
the	O
Enhanced	O
Video	O
Renderer	O
(	O
EVR	O
)	O
.	O
</s>
<s>
EVR	O
is	O
designed	O
to	O
work	O
with	O
Desktop	O
Window	O
Manager	O
and	O
supports	O
DXVA	B-General_Concept
2.0	I-General_Concept
,	O
which	O
is	O
available	O
on	O
Windows	B-Application
Vista	I-Application
and	O
Windows	B-Device
7	I-Device
.	O
</s>
<s>
Commanding	O
DirectShow	B-Library
to	O
play	O
a	O
file	O
is	O
a	O
relatively	O
simple	O
task	O
.	O
</s>
<s>
However	O
,	O
while	O
programming	O
more	O
advanced	O
customizations	O
,	O
such	O
as	O
commanding	O
DirectShow	B-Library
to	O
display	O
certain	O
windows	O
messages	O
from	O
the	O
video	O
window	O
or	O
creating	O
custom	O
filters	B-Application
,	O
many	O
developers	B-Application
complain	O
of	O
difficulties	O
.	O
</s>
<s>
It	O
is	O
regarded	O
as	O
one	O
of	O
Microsoft	O
's	O
most	O
complex	O
development	O
libraries/APIs	O
.	O
</s>
<s>
Developers	B-Application
rarely	O
create	O
DirectShow	B-Library
filters	B-Application
from	O
scratch	O
.	O
</s>
<s>
Rather	O
,	O
they	O
employ	O
DirectShow	B-Library
Base	O
Classes	O
.	O
</s>
<s>
The	O
Base	O
Classes	O
can	O
often	O
simplify	O
development	O
,	O
allowing	O
the	O
programmer	B-Application
to	O
bypass	O
certain	O
tasks	O
.	O
</s>
<s>
However	O
,	O
the	O
process	O
may	O
remain	O
relatively	O
complex	O
;	O
the	O
code	O
found	O
in	O
the	O
Base	O
Classes	O
is	O
nearly	O
half	O
the	O
size	O
of	O
the	O
entire	O
MFC	B-Language
library	I-Language
.	O
</s>
<s>
As	O
a	O
result	O
,	O
even	O
with	O
the	O
Base	O
Classes	O
,	O
the	O
number	O
of	O
COM	B-Application
objects	I-Application
that	O
DirectShow	B-Library
contains	O
often	O
overwhelms	O
developers	B-Application
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
DirectShow	B-Library
's	O
API	B-Application
deviates	O
from	O
traditional	O
COM	O
rules	O
,	O
particularly	O
with	O
regard	O
to	O
the	O
parameters	O
used	O
for	O
methods	B-Language
.	O
</s>
<s>
To	O
overcome	O
their	O
difficulties	O
with	O
DirectShow	B-Library
's	O
unique	O
COM	O
rules	O
,	O
developers	B-Application
often	O
turn	O
to	O
a	O
higher	O
level	O
API	B-Application
that	O
uses	O
DirectShow	B-Library
,	O
notably	O
,	O
Windows	O
Media	O
Player	O
SDK	B-Application
,	O
an	O
API	B-Application
provides	O
the	O
developer	B-Application
with	O
an	O
ActiveX	B-Application
Control	I-Application
that	O
has	O
fewer	O
COM	O
interfaces	O
to	O
deal	O
with	O
.	O
</s>
<s>
Although	O
DirectShow	B-Library
is	O
capable	O
of	O
dynamically	O
building	O
a	O
graph	O
to	O
render	O
a	O
given	O
media	O
type	O
,	O
in	O
certain	O
instances	O
it	O
is	O
difficult	O
for	O
developers	B-Application
to	O
rely	O
on	O
this	O
functionality	O
and	O
they	O
need	O
to	O
resort	O
to	O
manually	O
building	O
filter	B-Library
graphs	I-Library
if	O
the	O
resulting	O
filter	B-Library
graph	I-Library
is	O
variable	O
.	O
</s>
<s>
It	O
is	O
possible	O
for	O
filter	B-Library
graphs	I-Library
to	O
change	O
over	O
time	O
as	O
new	O
filters	B-Application
are	O
installed	O
on	O
the	O
computer	O
.	O
</s>
<s>
Codec	O
hell	O
(	O
a	O
term	O
derived	O
from	O
DLL	O
hell	O
)	O
is	O
when	O
multiple	O
DirectShow	B-Library
filters	B-Application
conflict	O
for	O
performing	O
the	O
same	O
task	O
.	O
</s>
<s>
A	O
large	O
number	O
of	O
companies	O
now	O
develop	O
codecs	O
in	O
the	O
form	O
of	O
DirectShow	B-Library
filters	B-Application
,	O
resulting	O
in	O
the	O
presence	O
of	O
several	O
filters	B-Application
that	O
can	O
decode	O
the	O
same	O
media	O
type	O
.	O
</s>
<s>
This	O
issue	O
is	O
further	O
exacerbated	O
by	O
DirectShow	B-Library
's	O
merit	O
system	O
,	O
where	O
filter	B-Application
implementations	O
end	O
up	O
competing	O
with	O
one	O
another	O
by	O
registering	O
themselves	O
with	O
increasingly	O
elevated	O
priority	O
.	O
</s>
<s>
Microsoft	O
's	O
Ted	O
Youmans	O
explained	O
that	O
"	O
DirectShow	B-Library
was	O
based	O
on	O
the	O
merit	O
system	O
,	O
with	O
the	O
idea	O
being	O
that	O
,	O
using	O
a	O
combination	O
of	O
the	O
filter	B-Application
’s	O
merit	O
and	O
how	O
specific	O
the	O
media	O
type/sub	O
type	O
is	O
,	O
one	O
could	O
reasonably	O
pick	O
the	O
right	O
codec	O
every	O
time	O
.	O
</s>
<s>
GraphEdit	B-Application
can	O
also	O
help	O
understanding	O
the	O
sequence	O
of	O
filters	B-Application
that	O
DirectShow	B-Library
is	O
using	O
to	O
render	O
the	O
media	O
file	O
.	O
</s>
<s>
Codec	O
hell	O
can	O
be	O
resolved	O
by	O
manually	O
building	O
filter	B-Library
graphs	I-Library
,	O
using	O
a	O
media	O
player	O
that	O
supports	O
ignoring	O
or	O
overriding	O
filter	B-Application
merits	O
,	O
or	O
by	O
using	O
a	O
filter	B-Application
manager	O
that	O
changes	O
filter	B-Application
merits	O
in	O
the	O
Windows	B-Protocol
Registry	I-Protocol
.	O
</s>
<s>
DirectShow	B-Library
,	O
being	O
a	O
developer-centric	O
framework	O
and	O
API	B-Application
,	O
does	O
not	O
directly	O
offer	O
end-user	O
control	O
over	O
encoding	O
content	O
,	O
nor	O
does	O
it	O
incorporate	O
a	O
user	O
interface	O
for	O
encoding	O
using	O
installed	O
codecs	O
or	O
to	O
different	O
formats	O
;	O
instead	O
,	O
it	O
relies	O
on	O
developers	B-Application
to	O
develop	O
software	O
using	O
the	O
API	B-Application
.	O
</s>
<s>
In	O
contrast	O
,	O
other	O
multimedia	B-Library
frameworks	I-Library
such	O
as	O
QuickTime	B-Application
or	O
Video	B-Device
for	I-Device
Windows	I-Device
allow	O
end-users	O
to	O
perform	O
basic	O
video-related	O
tasks	O
such	O
as	O
re-encoding	O
using	O
a	O
different	O
codec	O
and	O
editing	O
files	O
and	O
streams	O
.	O
</s>
<s>
The	O
convenience	O
offered	O
by	O
an	O
end-user	O
GUI	B-Application
is	O
apparent	O
since	O
the	O
AVI	O
format	O
and	O
codecs	O
used	O
by	O
Video	B-Device
for	I-Device
Windows	I-Device
still	O
remain	O
in	O
use	O
,	O
for	O
example	O
VirtualDub	B-Application
.	O
</s>
