<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
is	O
an	O
audio	O
compression	O
technology	O
developed	O
by	O
Dolby	O
Laboratories	O
.	O
</s>
<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
bitstreams	O
can	O
contain	O
audio	O
channels	O
and/or	O
audio	O
objects	O
.	O
</s>
<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
has	O
been	O
adopted	O
by	O
the	O
DVB	B-Application
project	I-Application
and	O
standardized	O
by	O
the	O
ETSI	O
.	O
</s>
<s>
On	O
March	O
10	O
,	O
2015	O
,	O
the	O
Advanced	B-Device
Television	I-Device
Systems	I-Device
Committee	I-Device
(	O
ATSC	O
)	O
announced	O
that	O
Dolby	B-Algorithm
AC-4	I-Algorithm
was	O
one	O
of	O
the	O
three	O
standards	O
proposed	O
for	O
the	O
audio	O
system	O
of	O
ATSC	B-Device
3.0	I-Device
.	O
</s>
<s>
On	O
July	O
14	O
,	O
2015	O
,	O
Dolby	O
Laboratories	O
announced	O
that	O
Sony	O
Visual	O
Products	O
and	O
Vizio	O
would	O
support	O
Dolby	B-Algorithm
AC-4	I-Algorithm
.	O
</s>
<s>
On	O
April	O
14	O
,	O
2016	O
,	O
Dolby	O
Laboratories	O
announced	O
that	O
Samsung	B-Application
would	O
ship	O
TVs	O
with	O
support	O
for	O
Dolby	B-Algorithm
AC-4	I-Algorithm
in	O
2017	O
.	O
</s>
<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
can	O
have	O
up	O
to	O
5.1	O
core	O
audio	O
channels	O
which	O
all	O
Dolby	B-Algorithm
AC-4	I-Algorithm
decoders	O
are	O
required	O
to	O
decode	O
.	O
</s>
<s>
Additional	O
audio	O
channels	O
may	O
be	O
encoded	O
as	O
side	O
signals	O
which	O
Dolby	B-Algorithm
AC-4	I-Algorithm
decoders	O
can	O
optionally	O
support	O
which	O
would	O
allow	O
for	O
the	O
delivery	O
of	O
7.1.4	O
channel	O
audio	O
.	O
</s>
<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
has	O
two	O
different	O
channel	O
based	O
encoding	O
tools	O
with	O
Advanced	O
Joint	O
Channel	O
Coding	O
(	O
A-JCC	O
)	O
used	O
for	O
low	O
bit	O
rates	O
and	O
Advanced	O
Coupling	O
(	O
A-CPL	O
)	O
used	O
for	O
high	O
bit	O
rates	O
.	O
</s>
<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
supports	O
up	O
to	O
7	O
audio	O
objects	O
with	O
a	O
core	O
decoder	O
and	O
can	O
optionally	O
support	O
additional	O
audio	O
objects	O
with	O
a	O
more	O
advanced	O
decoder	O
.	O
</s>
<s>
The	O
use	O
of	O
different	O
decoders	O
allows	O
Dolby	B-Algorithm
AC-4	I-Algorithm
to	O
support	O
lower	O
cost	O
devices	O
while	O
also	O
allowing	O
for	O
more	O
advanced	O
decoders	O
for	O
AV	O
receivers	O
.	O
</s>
<s>
Dolby	O
states	O
that	O
Dolby	B-Algorithm
AC-4	I-Algorithm
provides	O
a	O
50%	O
reduction	O
in	O
bit	O
rate	O
over	O
Dolby	O
Digital	O
Plus	O
.	O
</s>
<s>
When	O
Dolby	B-Algorithm
AC-4	I-Algorithm
was	O
tested	O
by	O
the	O
DVB	B-Application
the	O
MUSHRA	O
score	O
was	O
90	O
at	O
192	O
kbit/s	O
for	O
5.1	O
channel	O
audio	O
.	O
</s>
<s>
When	O
tested	O
for	O
ATSC	B-Device
3.0	I-Device
the	O
bit	O
rates	O
needed	O
for	O
the	O
required	O
audio	O
score	O
was	O
96	O
kbit/s	O
for	O
stereo	O
audio	O
,	O
192	O
kbit/s	O
for	O
5.1	O
channel	O
audio	O
,	O
and	O
288	O
kbit/s	O
for	O
7.1.4	O
channel	O
audio	O
.	O
</s>
<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
is	O
extensible	O
and	O
audio	O
substreams	O
allow	O
for	O
new	O
features	O
to	O
be	O
added	O
to	O
Dolby	B-Algorithm
AC-4	I-Algorithm
while	O
maintaining	O
compatibility	O
with	O
older	O
decoders	O
.	O
</s>
<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
is	O
covered	O
by	O
patents	O
and	O
requires	O
a	O
license	O
from	O
Dolby	O
Laboratories	O
.	O
</s>
<s>
Dolby	B-Algorithm
AC-4	I-Algorithm
has	O
a	O
consumer	O
royalty	O
rate	O
of	O
US	O
$0.15	O
to	O
US	O
$1.20	O
depending	O
on	O
the	O
type	O
of	O
device	O
and	O
volume	O
of	O
sales	O
.	O
</s>
<s>
Dolby	O
only	O
charges	O
for	O
one	O
technology	O
per	O
device	O
,	O
which	O
means	O
that	O
Dolby	B-Algorithm
AC-4	I-Algorithm
effectively	O
costs	O
nothing	O
in	O
devices	O
that	O
include	O
existing	O
Dolby	O
technologies	O
such	O
as	O
Dolby	O
Digital	O
Plus	O
.	O
</s>
