<s>
Context-adaptive	B-Algorithm
binary	I-Algorithm
arithmetic	I-Algorithm
coding	I-Algorithm
(	O
CABAC	B-Algorithm
)	O
is	O
a	O
form	O
of	O
entropy	B-Algorithm
encoding	I-Algorithm
used	O
in	O
the	O
H.264/MPEG	B-Application
-4	I-Application
AVC	I-Application
and	O
High	B-Algorithm
Efficiency	I-Algorithm
Video	I-Algorithm
Coding	I-Algorithm
(	O
HEVC	B-Algorithm
)	O
standards	O
.	O
</s>
<s>
It	O
is	O
a	O
lossless	B-Algorithm
compression	I-Algorithm
technique	O
,	O
although	O
the	O
video	O
coding	O
standards	O
in	O
which	O
it	O
is	O
used	O
are	O
typically	O
for	O
lossy	B-Algorithm
compression	I-Algorithm
applications	O
.	O
</s>
<s>
CABAC	B-Algorithm
is	O
notable	O
for	O
providing	O
much	O
better	O
compression	B-General_Concept
than	O
most	O
other	O
entropy	B-Algorithm
encoding	I-Algorithm
algorithms	O
used	O
in	O
video	O
encoding	O
,	O
and	O
it	O
is	O
one	O
of	O
the	O
key	O
elements	O
that	O
provides	O
the	O
H.264/AVC	B-Application
encoding	O
scheme	O
with	O
better	O
compression	B-General_Concept
capability	O
than	O
its	O
predecessors	O
.	O
</s>
<s>
In	O
H.264/MPEG	B-Application
-4	I-Application
AVC	I-Application
,	O
CABAC	B-Algorithm
is	O
only	O
supported	O
in	O
the	O
Main	O
and	O
higher	O
profiles	O
(	O
but	O
not	O
the	O
extended	O
profile	O
)	O
of	O
the	O
standard	O
,	O
as	O
it	O
requires	O
a	O
larger	O
amount	O
of	O
processing	O
to	O
decode	O
than	O
the	O
simpler	O
scheme	O
known	O
as	O
context-adaptive	B-Algorithm
variable-length	I-Algorithm
coding	I-Algorithm
(	O
CAVLC	B-Algorithm
)	O
that	O
is	O
used	O
in	O
the	O
standard	O
's	O
Baseline	O
profile	O
.	O
</s>
<s>
CABAC	B-Algorithm
is	O
also	O
difficult	O
to	O
parallelize	O
and	O
vectorize	O
,	O
so	O
other	O
forms	O
of	O
parallelism	O
(	O
such	O
as	O
spatial	O
region	O
parallelism	O
)	O
may	O
be	O
coupled	O
with	O
its	O
use	O
.	O
</s>
<s>
In	O
HEVC	B-Algorithm
,	O
CABAC	B-Algorithm
is	O
used	O
in	O
all	O
profiles	O
of	O
the	O
standard	O
.	O
</s>
<s>
CABAC	B-Algorithm
is	O
based	O
on	O
arithmetic	B-Algorithm
coding	I-Algorithm
,	O
with	O
a	O
few	O
innovations	O
and	O
changes	O
to	O
adapt	O
it	O
to	O
the	O
needs	O
of	O
video	O
encoding	O
standards	O
:	O
</s>
<s>
It	O
uses	O
a	O
multiplication-free	O
range	O
division	O
by	O
the	O
use	O
of	O
quantized	B-Algorithm
probability	O
ranges	O
and	O
probability	O
states	O
.	O
</s>
<s>
CABAC	B-Algorithm
has	O
multiple	O
probability	O
modes	O
for	O
different	O
contexts	O
.	O
</s>
<s>
Arithmetic	B-Algorithm
coding	I-Algorithm
is	O
finally	O
applied	O
to	O
compress	O
the	O
data	O
.	O
</s>
<s>
The	O
context	O
modeling	O
is	O
responsible	O
for	O
most	O
of	O
CABAC	B-Algorithm
's	O
roughly	O
10%	O
savings	O
in	O
bit	O
rate	O
over	O
the	O
CAVLC	B-Algorithm
entropy	B-Algorithm
coding	I-Algorithm
method	O
.	O
</s>
<s>
Binarization	O
:	O
CABAC	B-Algorithm
uses	O
Binary	O
Arithmetic	B-Algorithm
Coding	I-Algorithm
which	O
means	O
that	O
only	O
binary	O
decisions	O
(	O
1	O
or	O
0	O
)	O
are	O
encoded	O
.	O
</s>
<s>
a	O
transform	O
coefficient	O
or	O
motion	O
vector	O
)	O
is	O
"	O
binarized	O
"	O
or	O
converted	O
into	O
a	O
binary	O
code	O
prior	O
to	O
arithmetic	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
This	O
process	O
is	O
similar	O
to	O
the	O
process	O
of	O
converting	O
a	O
data	O
symbol	O
into	O
a	O
variable	O
length	O
code	O
but	O
the	O
binary	O
code	O
is	O
further	O
encoded	O
(	O
by	O
the	O
arithmetic	B-Algorithm
coder	I-Algorithm
)	O
prior	O
to	O
transmission	O
.	O
</s>
<s>
Arithmetic	B-Algorithm
encoding	I-Algorithm
:	O
An	O
arithmetic	B-Algorithm
coder	I-Algorithm
encodes	O
each	O
bin	O
according	O
to	O
the	O
selected	O
probability	O
model	O
.	O
</s>
<s>
These	O
estimates	O
determine	O
the	O
two	O
sub-ranges	O
that	O
the	O
arithmetic	B-Algorithm
coder	I-Algorithm
uses	O
to	O
encode	O
the	O
bin	O
.	O
</s>
<s>
The	O
range	O
representing	O
the	O
current	O
state	O
of	O
the	O
arithmetic	B-Algorithm
coder	I-Algorithm
is	O
quantized	B-Algorithm
to	O
a	O
small	O
range	O
of	O
pre-set	O
values	O
before	O
calculating	O
the	O
new	O
range	O
at	O
each	O
step	O
,	O
making	O
it	O
possible	O
to	O
calculate	O
the	O
new	O
range	O
using	O
a	O
look-up	O
table	O
(	O
i.e.	O
</s>
<s>
implementations	O
of	O
arithmetic	B-Algorithm
encoding	I-Algorithm
and	O
decoding	O
.	O
</s>
<s>
In	O
1986	O
,	O
IBM	O
researchers	O
Kottappuram	O
M	O
.	O
A	O
.	O
Mohiuddin	O
and	O
Jorma	O
Johannen	O
Rissanen	O
filed	O
a	O
patent	O
for	O
a	O
multiplication-free	O
binary	O
arithmetic	B-Algorithm
coding	I-Algorithm
algorithm	O
.	O
</s>
<s>
Lu	O
,	O
W	O
.	O
B	O
.	O
Pennebaker	O
,	O
L	O
.	O
Mitchell	O
and	O
G	O
.	O
G	O
.	O
Langdon	O
presented	O
an	O
adaptive	O
binary	O
arithmetic	B-Algorithm
coding	I-Algorithm
(	O
ABAC	O
)	O
algorithm	O
called	O
Q-Coder	O
.	O
</s>
<s>
The	O
above	O
patents	O
and	O
research	O
papers	O
,	O
along	O
several	O
others	O
from	O
IBM	O
and	O
Mitsubishi	O
Electric	O
,	O
were	O
later	O
cited	O
by	O
the	O
CCITT	O
and	O
Joint	O
Photographic	O
Experts	O
Group	O
as	O
the	O
basis	O
for	O
the	O
JPEG	O
image	B-General_Concept
compression	I-General_Concept
format	O
's	O
adaptive	O
binary	O
arithmetic	B-Algorithm
coding	I-Algorithm
algorithm	O
in	O
1992	O
.	O
</s>
<s>
However	O
,	O
encoders	O
and	O
decoders	O
of	O
the	O
JPEG	O
file	O
format	O
,	O
which	O
has	O
options	O
for	O
both	O
Huffman	B-General_Concept
encoding	I-General_Concept
and	O
arithmetic	B-Algorithm
coding	I-Algorithm
,	O
typically	O
only	O
support	O
the	O
Huffman	B-General_Concept
encoding	I-General_Concept
option	O
,	O
which	O
was	O
originally	O
because	O
of	O
patent	O
concerns	O
,	O
although	O
JPEG	O
's	O
arithmetic	B-Algorithm
coding	I-Algorithm
patents	O
have	O
since	O
expired	O
due	O
to	O
the	O
age	O
of	O
the	O
JPEG	O
standard	O
.	O
</s>
<s>
In	O
1999	O
,	O
Youngjun	O
Yoo	O
(	O
Texas	O
Instruments	O
)	O
,	O
Young	O
Gap	O
Kwon	O
and	O
Antonio	O
Ortega	O
(	O
University	O
of	O
Southern	O
California	O
)	O
presented	O
a	O
context-adaptive	O
form	O
of	O
binary	O
arithmetic	B-Algorithm
coding	I-Algorithm
.	O
</s>
<s>
The	O
modern	O
context-adaptive	B-Algorithm
binary	I-Algorithm
arithmetic	I-Algorithm
coding	I-Algorithm
(	O
CABAC	B-Algorithm
)	O
algorithm	O
was	O
commercially	O
introduced	O
with	O
the	O
H.264/MPEG	B-Application
-4	I-Application
AVC	I-Application
format	O
in	O
2003	O
.	O
</s>
