<s>
A	O
TV	B-Device
tuner	I-Device
card	I-Device
is	O
a	O
kind	O
of	O
television	B-Device
tuner	I-Device
that	O
allows	O
television	O
signals	O
to	O
be	O
received	O
by	O
a	O
computer	O
.	O
</s>
<s>
Most	O
TV	B-Device
tuners	I-Device
also	O
function	O
as	O
video	B-General_Concept
capture	I-General_Concept
cards	O
,	O
allowing	O
them	O
to	O
record	O
television	O
programs	O
onto	O
a	O
hard	B-Device
disk	I-Device
much	O
like	O
the	O
digital	B-Application
video	I-Application
recorder	I-Application
(	O
DVR	B-Application
)	O
does	O
.	O
</s>
<s>
The	O
interfaces	O
for	O
TV	B-Device
tuner	I-Device
cards	I-Device
are	O
most	O
commonly	O
either	O
PCI	B-Protocol
bus	I-Protocol
expansion	B-Device
card	I-Device
or	O
the	O
newer	O
PCI	B-Protocol
Express	O
(	O
PCIe	O
)	O
bus	B-General_Concept
for	O
many	O
modern	O
cards	O
,	O
but	O
PCMCIA	B-Architecture
,	O
ExpressCard	B-Device
,	O
or	O
USB	B-Protocol
devices	I-Protocol
also	O
exist	O
.	O
</s>
<s>
In	O
addition	O
,	O
some	O
video	B-Device
cards	I-Device
double	O
as	O
TV	B-Device
tuners	I-Device
,	O
notably	O
the	O
ATI	O
All-In-Wonder	O
series	O
.	O
</s>
<s>
The	O
card	O
contains	O
a	O
tuner	B-Device
and	O
an	O
analog-to-digital	O
converter	O
(	O
collectively	O
known	O
as	O
the	O
analog	O
front	O
end	O
)	O
along	O
with	O
demodulation	O
and	O
interface	O
logic	O
.	O
</s>
<s>
Some	O
lower-end	O
cards	O
lack	O
an	O
onboard	O
processor	O
and	O
,	O
like	O
a	O
Winmodem	B-Device
,	O
rely	O
on	O
the	O
system	O
's	O
CPU	B-Device
for	O
demodulation	O
.	O
</s>
<s>
There	O
are	O
many	O
types	O
of	O
tuner	B-Device
cards	I-Device
.	O
</s>
<s>
Analog	O
television	O
cards	O
output	O
a	O
raw	O
video	B-Application
stream	I-Application
,	O
suitable	O
for	O
real-time	O
viewing	O
but	O
ideally	O
requiring	O
some	O
sort	O
of	O
video	O
compression	O
if	O
it	O
is	O
to	O
be	O
recorded	O
.	O
</s>
<s>
Some	O
cards	O
also	O
have	O
analog	O
input	O
(	O
composite	O
video	O
or	O
S-Video	O
)	O
and	O
many	O
also	O
provide	O
a	O
radio	B-Device
tuner	I-Device
.	O
</s>
<s>
An	O
early	O
example	O
was	O
the	O
Aapps	O
Corp	O
.	O
MicroTV	O
for	O
Apple	B-Device
Macintosh	I-Device
II	I-Device
,	O
which	O
debuted	O
in	O
1989	O
.	O
</s>
<s>
More-advanced	O
TV	B-Device
tuners	I-Device
encode	O
the	O
signal	O
to	O
Motion	B-Application
JPEG	I-Application
or	O
MPEG	O
,	O
relieving	O
the	O
main	O
CPU	B-Device
of	O
this	O
load	O
.	O
</s>
<s>
A	O
hybrid	O
tuner	B-Device
has	O
one	O
tuner	B-Device
that	O
can	O
be	O
configured	O
to	O
act	O
as	O
an	O
analog	O
tuner	B-Device
or	O
a	O
digital	O
tuner	B-Device
.	O
</s>
<s>
The	O
card	O
operates	O
as	O
a	O
digital	O
tuner	B-Device
or	O
an	O
analog	O
tuner	B-Device
until	O
reconfigured	O
.	O
</s>
<s>
This	O
is	O
similar	O
to	O
a	O
hybrid	O
tuner	B-Device
,	O
except	O
there	O
are	O
two	O
separate	O
tuners	B-Device
on	O
the	O
card	O
.	O
</s>
<s>
The	O
card	O
operates	O
as	O
an	O
analog	O
tuner	B-Device
and	O
a	O
digital	O
tuner	B-Device
simultaneously	O
.	O
</s>
<s>
The	O
advantages	O
over	O
two	O
separate	O
cards	O
are	O
cost	O
and	O
utilization	O
of	O
expansion	B-Device
slots	I-Device
in	O
the	O
computer	O
.	O
</s>
<s>
As	O
many	O
regions	O
around	O
the	O
world	O
convert	O
from	O
analog	O
to	O
digital	O
broadcasts	O
,	O
these	O
tuners	B-Device
are	O
gaining	O
popularity	O
.	O
</s>
<s>
Like	O
the	O
analog	O
cards	O
,	O
the	O
Hybrid	O
and	O
Combo	O
tuners	B-Device
can	O
have	O
specialized	O
chips	O
on	O
the	O
tuner	B-Device
card	I-Device
to	O
perform	O
the	O
encoding	O
,	O
or	O
leave	O
this	O
task	O
to	O
the	O
CPU	B-Device
.	O
</s>
<s>
The	O
tuner	B-Device
cards	I-Device
with	O
this	O
'	O
hardware	O
encoding	O
 '	O
are	O
generally	O
thought	O
of	O
as	O
being	O
higher	O
quality	O
.	O
</s>
<s>
Small	O
USB	B-Protocol
tuner	B-Device
sticks	O
have	O
become	O
more	O
popular	O
in	O
2006	O
and	O
2007	O
and	O
are	O
expected	O
to	O
increase	O
in	O
popularity	O
.	O
</s>
<s>
These	O
small	O
tuners	B-Device
generally	O
do	O
not	O
have	O
hardware	O
encoding	O
due	O
to	O
size	O
and	O
heat	O
constraints	O
.	O
</s>
<s>
While	O
most	O
TV	B-Device
tuners	I-Device
are	O
limited	O
to	O
the	O
radio	O
frequencies	O
and	O
video	O
formats	O
used	O
in	O
the	O
country	O
of	O
sale	O
,	O
many	O
TV	B-Device
tuners	I-Device
used	O
in	O
computers	O
use	O
DSP	B-General_Concept
,	O
so	O
a	O
firmware	B-Application
upgrade	O
is	O
often	O
all	O
that	O
's	O
necessary	O
to	O
change	O
the	O
supported	O
video	O
format	O
.	O
</s>
<s>
Many	O
newer	O
TV	B-Device
tuners	I-Device
have	O
flash	B-Device
memory	I-Device
big	O
enough	O
to	O
hold	O
the	O
firmware	B-Application
sets	O
for	O
decoding	O
several	O
different	O
video	O
formats	O
,	O
making	O
it	O
possible	O
to	O
use	O
the	O
tuner	B-Device
in	O
many	O
countries	O
without	O
having	O
to	O
flash	O
the	O
firmware	B-Application
.	O
</s>
<s>
Many	O
TV	B-Device
tuners	I-Device
can	O
function	O
as	O
FM	O
radios	O
;	O
this	O
is	O
because	O
there	O
are	O
similarities	O
between	O
broadcast	O
television	O
and	O
FM	O
radio	O
.	O
</s>
<s>
The	O
FM	O
radio	O
spectrum	O
is	O
close	O
to	O
(	O
or	O
even	O
inside	O
)	O
that	O
used	O
by	O
VHF	B-Algorithm
terrestrial	O
TV	O
broadcasts	O
.	O
</s>
<s>
External	O
TV	B-Device
tuner	I-Device
card	I-Device
attachments	O
are	O
available	O
for	O
mobile	O
phone	O
handsets	O
like	O
the	O
iPhone	B-Device
,	O
for	O
watching	O
mobile	B-Application
TV	I-Application
,	O
via	O
TV	O
stations	O
on	O
1seg	B-Device
in	O
Japan	O
(	O
SoftBank	O
)	O
,	O
and	O
for	O
soon	O
for	O
the	O
proprietary	O
subscription-based	O
MediaFLO	B-Device
in	O
the	O
U.S.	O
(	O
Qualcomm	O
)	O
.	O
</s>
<s>
There	O
is	O
also	O
a	O
"	O
converter	O
"	O
for	O
watching	O
DVB-H	B-Protocol
in	O
Europe	O
and	O
elsewhere	O
via	O
WiFi	O
streaming	B-Application
video	I-Application
(	O
PacketVideo	O
)	O
.	O
</s>
<s>
Video	B-General_Concept
capture	I-General_Concept
cards	O
are	O
a	O
class	O
of	O
video	B-General_Concept
capture	I-General_Concept
devices	O
designed	O
to	O
plug	O
directly	O
into	O
expansion	B-Device
slots	I-Device
in	O
personal	O
computers	O
and	O
servers	O
.	O
</s>
<s>
Models	O
from	O
many	O
manufacturers	O
are	O
available	O
;	O
all	O
comply	O
with	O
one	O
of	O
the	O
popular	O
host	O
bus	B-General_Concept
standards	O
including	O
PCI	B-Protocol
,	O
newer	O
PCI	B-Protocol
Express	O
(	O
PCIe	O
)	O
or	O
AGP	B-Architecture
bus	B-General_Concept
interfaces	O
.	O
</s>
<s>
These	O
cards	O
typically	O
include	O
one	O
or	O
more	O
software	B-Application
drivers	I-Application
to	O
expose	O
the	O
cards	O
 '	O
features	O
,	O
via	O
various	O
operating	B-General_Concept
systems	I-General_Concept
,	O
to	O
software	O
applications	O
that	O
further	O
process	O
the	O
video	O
for	O
specific	O
purposes	O
.	O
</s>
<s>
As	O
a	O
class	O
,	O
the	O
cards	O
are	O
used	O
to	O
capture	O
baseband	O
analog	O
composite	O
video	O
,	O
S-Video	O
,	O
and	O
,	O
in	O
models	O
equipped	O
with	O
tuners	B-Device
,	O
RF	O
modulated	O
video	O
.	O
</s>
<s>
Some	O
specialized	O
cards	O
support	O
digital	O
video	O
via	O
digital	O
video	O
delivery	O
standards	O
including	O
Serial	B-Protocol
Digital	I-Protocol
Interface	I-Protocol
(	O
SDI	O
)	O
and	O
,	O
more	O
recently	O
,	O
the	O
emerging	O
HDMI	B-Protocol
standard	O
.	O
</s>
<s>
These	O
models	O
often	O
support	O
both	O
standard	O
definition	O
(	O
SD	O
)	O
and	O
high	O
definition	O
(	O
HD	B-Device
)	O
variants	O
.	O
</s>
<s>
While	O
most	O
PCI	B-Protocol
and	O
PCI-Express	O
capture	O
devices	O
are	O
dedicated	O
to	O
that	O
purpose	O
,	O
AGP	B-Architecture
capture	O
devices	O
are	O
usually	O
included	O
with	O
the	O
graphics	O
adapted	O
on	O
the	O
board	O
as	O
an	O
all-in-one	O
package	O
.	O
</s>
<s>
Unlike	O
video	B-Device
editing	I-Device
cards	I-Device
,	O
these	O
cards	O
tend	O
to	O
not	O
have	O
dedicated	O
hardware	O
for	O
processing	O
video	O
beyond	O
the	O
analog-to-digital	O
conversion	O
.	O
</s>
<s>
Most	O
,	O
but	O
not	O
all	O
,	O
video	B-General_Concept
capture	I-General_Concept
cards	O
also	O
support	O
one	O
or	O
more	O
channels	O
of	O
audio	O
.	O
</s>
<s>
New	O
technologies	O
allow	O
PCI-Express	O
and	O
HD-SDI	B-Protocol
to	O
be	O
implemented	O
on	O
video	B-General_Concept
capture	I-General_Concept
cards	O
at	O
lower	O
costs	O
than	O
before	O
.	O
</s>
<s>
There	O
are	O
many	O
applications	O
for	O
video	B-General_Concept
capture	I-General_Concept
cards	O
like	O
EasyCap	O
including	O
converting	O
a	O
live	O
analog	O
source	O
into	O
some	O
type	O
of	O
analog	O
or	O
digital	O
media	O
,	O
(	O
such	O
as	O
a	O
VHS	O
tape	O
to	O
a	O
DVD	O
)	O
,	O
archiving	O
,	O
video	O
editing	O
,	O
scheduled	O
recording	O
(	O
such	O
as	O
a	O
DVR	B-Application
)	O
,	O
television	O
tuning	O
,	O
or	O
video	O
surveillance	O
.	O
</s>
<s>
Capture	B-General_Concept
cards	I-General_Concept
can	O
be	O
used	O
for	O
recording	O
a	O
video	O
game	O
longplay	O
(	O
LP	O
)	O
so	O
gamers	O
can	O
make	O
walkthrough	O
gameplay	O
videos	O
.	O
</s>
<s>
One	O
of	O
the	O
most	O
popular	O
applications	O
for	O
video	B-General_Concept
capture	I-General_Concept
cards	O
is	O
to	O
capture	B-General_Concept
video	I-General_Concept
and	O
audio	O
for	O
live	O
Internet	O
video	B-Application
streaming	I-Application
.	O
</s>
<s>
The	O
live	O
stream	O
can	O
also	O
be	O
simultaneously	O
archived	O
and	O
formatted	O
for	O
video	B-Application
on	I-Application
demand	I-Application
.	O
</s>
<s>
The	O
capture	B-General_Concept
cards	I-General_Concept
used	O
for	O
this	O
purpose	O
are	O
typically	O
purchased	O
,	O
installed	O
,	O
and	O
configured	O
in	O
host	O
PC	O
systems	O
by	O
hobbyists	O
or	O
systems	O
integrators	O
.	O
</s>
<s>
Some	O
care	O
is	O
required	O
to	O
select	O
suitable	O
host	O
systems	O
for	O
video	O
encoding	O
,	O
particularly	O
HD	B-Device
applications	O
which	O
are	O
more	O
affected	O
by	O
CPU	B-Device
performance	O
,	O
number	O
of	O
CPU	B-Architecture
cores	I-Architecture
,	O
and	O
certain	O
motherboard	B-Device
characteristics	O
that	O
heavily	O
influence	O
capture	O
performance	O
.	O
</s>
