<s>
The	O
Real	B-Protocol
Time	I-Protocol
Streaming	I-Protocol
Protocol	I-Protocol
(	O
RTSP	B-Protocol
)	O
is	O
an	O
application-level	O
network	O
protocol	O
designed	O
for	O
multiplexing	B-Architecture
and	O
packetizing	O
multimedia	O
transport	O
streams	O
(	O
such	O
as	O
interactive	O
media	O
,	O
video	O
and	O
audio	O
)	O
over	O
a	O
suitable	O
transport	O
protocol	O
.	O
</s>
<s>
RTSP	B-Protocol
is	O
used	O
in	O
entertainment	O
and	O
communications	O
systems	O
to	O
control	O
streaming	O
media	O
servers	O
.	O
</s>
<s>
Clients	O
of	O
media	O
servers	O
issue	O
commands	O
such	O
as	O
play	O
,	O
record	O
and	O
pause	O
,	O
to	O
facilitate	O
real-time	O
control	O
of	O
the	O
media	O
streaming	O
from	O
the	O
server	B-Application
to	O
a	O
client	O
(	O
video	B-Application
on	I-Application
demand	I-Application
)	O
or	O
from	O
a	O
client	O
to	O
the	O
server	B-Application
(	O
voice	O
recording	O
)	O
.	O
</s>
<s>
RTSP	B-Protocol
was	O
developed	O
by	O
RealNetworks	O
,	O
Netscape	B-Protocol
and	O
Columbia	O
University	O
.	O
</s>
<s>
The	O
first	O
draft	O
was	O
submitted	O
to	O
IETF	O
in	O
October	O
1996	O
by	O
Netscape	B-Protocol
and	O
Progressive	O
Networks	O
,	O
after	O
which	O
Henning	O
Schulzrinne	O
from	O
Columbia	O
University	O
submitted	O
"	O
RTSP՚	O
"	O
(	O
"	O
RTSP	B-Protocol
prime	O
"	O
)	O
in	O
December	O
1996	O
.	O
</s>
<s>
The	O
Proposed	O
Standard	O
for	O
RTSP	B-Protocol
was	O
published	O
as	O
RFC	O
2326	O
in	O
1998	O
.	O
</s>
<s>
RTSP	B-Protocol
2.0	O
published	O
as	O
RFC	O
7826	O
in	O
2016	O
as	O
a	O
replacement	O
of	O
RTSP	B-Protocol
1.0	O
.	O
</s>
<s>
RTSP	B-Protocol
2.0	O
is	O
based	O
on	O
RTSP	B-Protocol
1.0	O
but	O
is	O
not	O
backwards	O
compatible	O
other	O
than	O
in	O
the	O
basic	O
version	O
negotiation	O
mechanism	O
,	O
and	O
remains	O
a	O
"	O
Proposed	O
Standard	O
"	O
.	O
</s>
<s>
The	O
transmission	O
of	O
streaming	O
data	O
itself	O
is	O
not	O
a	O
task	O
of	O
RTSP	B-Protocol
.	O
</s>
<s>
Most	O
RTSP	B-Protocol
servers	O
use	O
the	O
Real-time	B-Protocol
Transport	I-Protocol
Protocol	I-Protocol
(	O
RTP	B-Protocol
)	O
in	O
conjunction	O
with	O
Real-time	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
(	O
RTCP	B-Protocol
)	O
for	O
media	O
stream	O
delivery	O
.	O
</s>
<s>
The	O
RTSP	B-Protocol
server	B-Application
software	O
from	O
RealNetworks	O
,	O
for	O
example	O
,	O
also	O
used	O
RealNetworks	O
 '	O
proprietary	O
Real	B-Protocol
Data	I-Protocol
Transport	I-Protocol
(	O
RDT	O
)	O
.	O
</s>
<s>
While	O
similar	O
in	O
some	O
ways	O
to	O
HTTP	B-Protocol
,	O
RTSP	B-Protocol
defines	O
control	O
sequences	O
useful	O
in	O
controlling	O
multimedia	O
playback	O
.	O
</s>
<s>
While	O
HTTP	B-Protocol
is	O
stateless	B-Protocol
,	O
RTSP	B-Protocol
has	O
a	O
state	O
;	O
an	O
identifier	O
is	O
used	O
when	O
needed	O
to	O
track	O
concurrent	O
sessions	O
.	O
</s>
<s>
Like	O
HTTP	B-Protocol
,	O
RTSP	B-Protocol
uses	O
TCP	B-Protocol
to	O
maintain	O
an	O
end-to-end	O
connection	O
and	O
,	O
while	O
most	O
RTSP	B-Protocol
control	O
messages	O
are	O
sent	O
by	O
the	O
client	O
to	O
the	O
server	B-Application
,	O
some	O
commands	O
travel	O
in	O
the	O
other	O
direction	O
(	O
i.e.	O
</s>
<s>
from	O
server	B-Application
to	O
client	O
)	O
.	O
</s>
<s>
Presented	O
here	O
are	O
the	O
basic	O
RTSP	B-Protocol
requests	O
.	O
</s>
<s>
Some	O
typical	O
HTTP	B-Protocol
requests	I-Protocol
,	O
like	O
the	O
OPTIONS	O
request	O
,	O
are	O
also	O
available	O
.	O
</s>
<s>
The	O
default	O
transport	O
layer	O
port	B-Protocol
number	I-Protocol
is	O
554	O
for	O
both	O
TCP	B-Protocol
and	O
UDP	B-Protocol
,	O
the	O
latter	O
being	O
rarely	O
used	O
for	O
the	O
control	O
requests	O
.	O
</s>
<s>
An	O
OPTIONS	O
request	O
returns	O
the	O
request	O
types	O
the	O
server	B-Application
will	O
accept	O
.	O
</s>
<s>
A	O
DESCRIBE	O
request	O
includes	O
an	O
RTSP	B-Protocol
URL	O
(	O
rtsp://...	O
)	O
,	O
and	O
the	O
type	O
of	O
reply	O
data	O
that	O
can	O
be	O
handled	O
.	O
</s>
<s>
This	O
reply	O
includes	O
the	O
presentation	O
description	O
,	O
typically	O
in	O
Session	B-Language
Description	I-Language
Protocol	I-Language
(	O
SDP	O
)	O
format	O
.	O
</s>
<s>
In	O
the	O
typical	O
case	O
,	O
there	O
is	O
one	O
media	O
stream	O
each	O
for	O
audio	O
and	O
video	B-Application
streams	I-Application
.	O
</s>
<s>
This	O
specifier	O
typically	O
includes	O
a	O
local	O
port	O
for	O
receiving	O
RTP	B-Protocol
data	O
(	O
audio	O
or	O
video	O
)	O
,	O
and	O
another	O
for	O
RTCP	B-Protocol
data	O
(	O
meta	O
information	O
)	O
.	O
</s>
<s>
The	O
server	B-Application
reply	O
usually	O
confirms	O
the	O
chosen	O
parameters	O
,	O
and	O
fills	O
in	O
the	O
missing	O
parts	O
,	O
such	O
as	O
the	O
server	B-Application
's	O
chosen	O
ports	O
.	O
</s>
<s>
The	O
server	B-Application
decides	O
whether	O
to	O
store	O
the	O
recorded	O
data	O
under	O
the	O
request	O
URI	O
or	O
another	O
URI	O
.	O
</s>
<s>
If	O
the	O
server	B-Application
does	O
not	O
use	O
the	O
request	O
URI	O
,	O
the	O
response	O
should	O
be	O
201	O
and	O
contain	O
an	O
entity	O
which	O
describes	O
the	O
states	O
of	O
the	O
request	O
and	O
refers	O
to	O
the	O
new	O
resource	O
,	O
and	O
a	O
Location	O
header	O
.	O
</s>
<s>
When	O
sent	O
from	O
client	O
to	O
server	B-Application
,	O
ANNOUNCE	O
posts	O
the	O
description	O
of	O
a	O
presentation	O
or	O
media	O
object	O
identified	O
by	O
the	O
request	O
URL	O
to	O
a	O
server	B-Application
.	O
</s>
<s>
When	O
sent	O
from	O
server	B-Application
to	O
client	O
,	O
ANNOUNCE	O
updates	O
the	O
session	O
description	O
in	O
real	O
time	O
.	O
</s>
<s>
It	O
stops	O
all	O
media	O
streams	O
and	O
frees	O
all	O
session-related	O
data	O
on	O
the	O
server	B-Application
.	O
</s>
<s>
GET_PARAMETER	O
with	O
no	O
entity	O
body	O
may	O
be	O
used	O
to	O
test	O
client	O
or	O
server	B-Application
liveness	O
(	O
"	O
ping	O
"	O
)	O
.	O
</s>
<s>
A	O
REDIRECT	O
request	O
informs	O
the	O
client	O
that	O
it	O
must	O
connect	O
to	O
another	O
server	B-Application
location	O
.	O
</s>
<s>
Certain	O
firewall	O
designs	O
and	O
other	O
circumstances	O
may	O
force	O
a	O
server	B-Application
to	O
interleave	O
RTSP	B-Protocol
methods	O
and	O
stream	O
data	O
.	O
</s>
<s>
This	O
interleaving	O
should	O
generally	O
be	O
avoided	O
unless	O
necessary	O
since	O
it	O
complicates	O
client	O
and	O
server	B-Application
operation	O
and	O
imposes	O
additional	O
overhead	O
.	O
</s>
<s>
Interleaved	O
binary	O
data	O
SHOULD	O
only	O
be	O
used	O
if	O
RTSP	B-Protocol
is	O
carried	O
over	O
TCP	B-Protocol
.	O
</s>
<s>
Stream	O
data	O
such	O
as	O
RTP	B-Protocol
packets	O
is	O
encapsulated	O
by	O
an	O
ASCII	O
dollar	O
sign	O
(	O
24	O
hexadecimal	O
)	O
,	O
followed	O
by	O
a	O
one-byte	O
channel	O
identifier	O
,	O
followed	O
by	O
the	O
length	O
of	O
the	O
encapsulated	O
binary	O
data	O
as	O
a	O
binary	O
,	O
two-byte	O
integer	O
in	O
network	O
byte	O
order	O
.	O
</s>
<s>
Each	O
$	O
block	O
contains	O
exactly	O
one	O
upper-layer	O
protocol	O
data	O
unit	O
,	O
e.g.	O
,	O
one	O
RTP	B-Protocol
packet	O
.	O
</s>
<s>
RTSP	B-Protocol
using	O
RTP	B-Protocol
and	O
RTCP	B-Protocol
allows	O
for	O
the	O
implementation	O
of	O
rate	O
adaptation	O
.	O
</s>
<s>
Darwin	B-Application
Streaming	I-Application
Server	I-Application
:	O
Open-sourced	O
version	O
of	O
QuickTime	B-Operating_System
Streaming	I-Operating_System
Server	I-Operating_System
maintained	O
by	O
Apple	O
.	O
</s>
<s>
Feng	B-Application
:	O
Lean	O
and	O
mean	O
streaming	O
server	B-Application
with	O
a	O
focus	O
on	O
RFC	O
compliance	O
.	O
</s>
<s>
GStreamer	B-Language
based	O
RTSP	B-Protocol
Server	B-Application
and	O
client	O
.	O
</s>
<s>
Helix	B-Application
DNA	I-Application
Server	I-Application
:	O
RealNetworks	O
 '	O
streaming	O
server	B-Application
.	O
</s>
<s>
LIVE555	B-Language
liveMedia	I-Language
/	I-Language
openRTSP	I-Language
:	O
Open	O
source	O
C++	B-Language
server	B-Application
and	O
client	O
libraries	O
used	O
in	O
well-known	O
clients	O
like	O
VLC	B-Application
and	O
mplayer	B-Application
.	O
</s>
<s>
Nimble	B-Application
Streamer	I-Application
supports	O
RTSP	B-Protocol
pull	O
and	O
announce	O
input	O
with	O
TCP	B-Protocol
interleaved	O
playback	O
output	O
.	O
</s>
<s>
pvServer	B-Application
:	O
Formerly	O
called	O
PacketVideo	O
Streaming	O
Server	B-Application
,	O
this	O
is	O
Alcatel-Lucent	O
'	O
s	O
streaming	O
server	B-Application
product	O
.	O
</s>
<s>
QuickTime	B-Operating_System
Streaming	I-Operating_System
Server	I-Operating_System
:	O
Apple	O
's	O
closed-source	O
streaming	O
server	B-Application
that	O
ships	O
with	O
Mac	O
OS	O
X	O
Server	B-Application
.	O
</s>
<s>
VideoLAN	B-Application
:	O
Open	O
source	O
media	B-Device
player	I-Device
and	O
streaming	O
server	B-Application
.	O
</s>
<s>
YouTube	B-General_Concept
implemented	O
a	O
mobile	B-Application
web	I-Application
front	O
end	O
in	O
June	O
2007	O
which	O
serves	O
video	O
through	O
this	O
protocol	O
.	O
</s>
<s>
Many	O
CCTV	O
/	O
Security	O
cameras	O
,	O
often	O
called	O
IP	B-Algorithm
cameras	I-Algorithm
,	O
support	O
RTSP	B-Protocol
streaming	O
too	O
,	O
especially	O
those	O
with	O
ONVIF	O
profiles	O
G	O
,	O
S	O
,	O
T	O
.	O
</s>
<s>
LIVE555	B-Language
liveMedia	I-Language
/	I-Language
openRTSP	I-Language
:	O
Open	O
source	O
C++	B-Language
server	B-Application
and	O
client	O
libraries	O
used	O
in	O
well-known	O
clients	O
like	O
VLC	B-Application
and	O
mplayer	B-Application
.	O
</s>
