<s>
An	O
Ogg	B-Application
page	I-Application
is	O
a	O
unit	O
of	O
data	O
in	O
an	O
Ogg	O
bitstream	O
,	O
usually	O
between	O
4kB	O
and	O
8kB	O
,	O
with	O
a	O
maximum	O
size	O
of	O
65,307	O
bytes	O
.	O
</s>
<s>
One	O
of	O
the	O
purposes	O
of	O
multimedia	O
container	O
formats	O
is	O
to	O
allow	O
multiple	O
codecs	B-General_Concept
to	O
be	O
muxed	B-Architecture
into	O
a	O
single	O
file	O
or	O
stream	O
.	O
</s>
<s>
The	O
viewpoint	O
held	O
by	O
Christopher	O
Montgomery	O
,	O
creator	O
of	O
the	O
Ogg	O
format	O
,	O
is	O
that	O
the	O
units	O
of	O
muxed	B-Architecture
codec	B-General_Concept
data	O
should	O
be	O
a	O
separate	O
abstraction	B-Application
layer	O
from	O
the	O
units	O
of	O
data	O
used	O
by	O
the	O
codec	B-General_Concept
in	O
order	O
to	O
limit	O
the	O
amount	O
of	O
buffering	O
necessary	O
when	O
decoding	O
the	O
contained	O
data	O
.	O
</s>
<s>
In	O
his	O
opinion	O
,	O
which	O
is	O
supported	O
by	O
other	O
developers	O
working	O
with	O
the	O
Xiph.org	B-Application
Foundation	I-Application
,	O
this	O
gives	O
Ogg	O
a	O
technical	O
advantage	O
over	O
alternative	O
bitstream	B-General_Concept
formats	I-General_Concept
such	O
as	O
AVI	O
,	O
QuickTime	B-Application
,	O
and	O
MPEG	O
.	O
</s>
<s>
Each	O
Ogg	B-Application
page	I-Application
also	O
provides	O
the	O
time	O
offset	O
of	O
the	O
contained	O
data	O
,	O
which	O
allows	O
efficient	O
seeking	O
that	O
is	O
both	O
accurate	O
and	O
compatible	O
with	O
streaming	O
.	O
</s>
<s>
Every	O
Ogg	B-Application
page	I-Application
begins	O
with	O
the	O
four-byte	O
magic	O
string	O
"	O
OggS	O
"	O
.	O
</s>
<s>
The	O
version	O
field	O
had	O
originally	O
been	O
intended	O
to	O
allow	O
multiple	O
Ogg	B-Application
page	I-Application
types	O
tuned	O
for	O
different	O
payloads	O
to	O
coexist	O
in	O
the	O
same	O
stream	O
.	O
</s>
<s>
The	O
next	O
8	O
bytes	O
,	O
or	O
64	O
bits	O
,	O
is	O
called	O
the	O
absolute	O
granule	O
position	O
which	O
is	O
a	O
synthetic	O
value	O
that	O
encodes	O
the	O
Decode	O
Timestamp	O
,	O
the	O
Presentation	B-Protocol
time	I-Protocol
stamp	I-Protocol
and	O
distance	O
to	O
first-needed	O
reference	O
.	O
</s>
<s>
The	O
exact	O
encoding	O
of	O
the	O
granule	O
position	O
is	O
up	O
to	O
a	O
specific	O
codec	B-General_Concept
.	O
</s>
<s>
It	O
is	O
also	O
intended	O
to	O
be	O
used	O
like	O
a	O
weak	O
hash	O
so	O
that	O
a	O
collision	O
is	O
very	O
unlikely	O
when	O
multiplexing	B-Architecture
different	O
streams	O
,	O
which	O
eliminates	O
the	O
need	O
for	O
continuous	O
recalculation	O
of	O
page	O
headers	O
at	O
every	O
multiplexing	B-Architecture
step	O
.	O
</s>
<s>
In	O
comparison	O
to	O
other	O
container	O
formats	O
,	O
the	O
large	O
number	O
of	O
bits	O
also	O
allows	O
direct	O
UDP	B-Protocol
unicast/multicast	O
with	O
Ogg	O
handling	O
reordering	O
and	O
reassembly	O
.	O
</s>
<s>
The	O
next	O
4	O
bytes	O
,	O
starting	O
at	O
the	O
23rd	O
byte	O
of	O
the	O
page	O
,	O
is	O
the	O
CRC	O
checksum	B-Algorithm
of	O
the	O
page	O
.	O
</s>
<s>
One	O
of	O
the	O
common	O
uses	O
of	O
Ogg	B-Application
pages	I-Application
is	O
to	O
allow	O
the	O
editing	O
of	O
Ogg	O
files	O
without	O
a	O
reduction	O
in	O
quality	O
or	O
the	O
need	O
to	O
transcode	B-Device
files	O
.	O
</s>
