<s>
Layered	B-General_Concept
coding	I-General_Concept
is	O
a	O
type	O
of	O
data	B-General_Concept
compression	I-General_Concept
for	O
digital	O
video	O
or	O
digital	O
audio	O
where	O
the	O
result	O
of	O
compressing	O
the	O
source	O
video	O
data	O
is	O
not	O
just	O
one	O
compressed	B-General_Concept
data	I-General_Concept
stream	O
,	O
as	O
in	O
other	O
types	O
of	O
compression	O
,	O
but	O
multiple	O
streams	O
,	O
called	O
layers	O
,	O
allowing	O
decompression	O
even	O
if	O
some	O
layers	O
are	O
missing	O
.	O
</s>
<s>
With	O
layered	B-General_Concept
coding	I-General_Concept
,	O
multiple	O
data	B-General_Concept
streams	I-General_Concept
or	O
layers	O
are	O
created	O
when	O
compressing	O
the	O
original	O
video	O
stream	O
.	O
</s>
<s>
This	O
is	O
in	O
contrast	O
to	O
other	O
types	O
of	O
compression	O
,	O
where	O
the	O
result	O
is	O
typically	O
a	O
single	O
data	B-General_Concept
stream	I-General_Concept
.	O
</s>
<s>
Layered	B-General_Concept
coding	I-General_Concept
is	O
helpful	O
when	O
the	O
same	O
video	O
stream	O
needs	O
to	O
be	O
available	O
in	O
different	O
qualities	O
,	O
for	O
example	O
for	O
adaptive	O
bitrate	O
streaming	O
.	O
</s>
<s>
Without	O
layered	B-General_Concept
coding	I-General_Concept
,	O
the	O
source	O
video	O
stream	O
must	O
be	O
encoded	O
multiple	O
times	O
to	O
obtain	O
compressed	O
streams	O
with	O
different	O
qualities	O
and	O
bitrates	O
.	O
</s>
<s>
Layered	B-General_Concept
coding	I-General_Concept
allows	O
only	O
encoding	O
a	O
single	O
time	O
,	O
because	O
streams	O
with	O
different	O
qualities	O
can	O
be	O
obtained	O
by	O
discarding	O
layers	O
.	O
</s>
<s>
Layered	B-General_Concept
coding	I-General_Concept
is	O
similar	O
to	O
multiple	O
description	O
coding	O
in	O
that	O
both	O
produce	O
multiple	O
compressed	O
streams	O
that	O
can	O
be	O
combined	O
.	O
</s>
<s>
Scalable	B-Application
Video	I-Application
Coding	I-Application
is	O
a	O
video	O
compression	O
standard	O
that	O
makes	O
use	O
of	O
layered	B-General_Concept
coding	I-General_Concept
.	O
</s>
