<s>
x265	B-Language
is	O
a	O
software	B-General_Concept
codec	I-General_Concept
for	O
creating	O
digital	O
video	O
streams	O
in	O
the	O
High	B-Algorithm
Efficiency	I-Algorithm
Video	I-Algorithm
Coding	I-Algorithm
(	O
HEVC/H.265	O
)	O
video	O
compression	O
format	O
developed	O
by	O
the	O
Joint	B-Algorithm
Collaborative	I-Algorithm
Team	I-Algorithm
on	I-Algorithm
Video	I-Algorithm
Coding	I-Algorithm
(	O
JCT-VC	O
)	O
.	O
</s>
<s>
It	O
is	O
available	O
as	O
a	O
command-line	B-Device
app	I-Device
or	O
a	O
software	B-Library
library	I-Library
,	O
under	O
the	O
terms	O
of	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
(	O
GPL	B-License
)	O
version	O
2	O
or	O
later	O
;	O
however	O
,	O
customers	O
may	O
request	O
a	O
commercial	O
license	O
.	O
</s>
<s>
x265	B-Language
builds	O
on	O
source	O
code	O
from	O
x264	B-Language
,	O
an	O
open-source	O
video	O
encoder	O
for	O
the	O
previous	O
MPEG	O
video	O
coding	O
standard	O
,	O
H.264/MPEG	B-Application
-4	I-Application
AVC	I-Application
.	O
</s>
<s>
The	O
project	O
has	O
licensed	O
the	O
rights	O
to	O
use	O
the	O
x264	B-Language
source	O
code	O
.	O
</s>
<s>
Development	O
on	O
x265	B-Language
began	O
in	O
March	O
2013	O
.	O
</s>
<s>
MulticoreWare	O
made	O
the	O
source	O
code	O
for	O
x265	B-Language
publicly	O
available	O
on	O
July	O
23	O
,	O
2013	O
.	O
</s>
<s>
The	O
x265	B-Language
project	O
was	O
initially	O
funded	O
by	O
a	O
small	O
group	O
of	O
charter	O
licensee	O
companies	O
that	O
direct	O
the	O
development	O
requirements	O
and	O
receive	O
commercial	O
licenses	O
to	O
use	O
x265	B-Language
in	O
their	O
products	O
without	O
having	O
to	O
release	O
their	O
products	O
under	O
the	O
GPL	B-License
2	O
license	O
.	O
</s>
<s>
In	O
February	O
2014	O
,	O
x265	B-Language
was	O
integrated	O
into	O
the	O
popular	O
multimedia	O
transcoding	O
tool	O
FFmpeg	B-Library
and	O
its	O
fork	O
Libav	B-Language
.	O
</s>
<s>
x265	B-Language
source	O
code	O
is	O
written	O
in	O
C++	B-Language
and	O
x86	B-Language
assembly	I-Language
.	O
</s>
<s>
x265	B-Language
supports	O
the	O
Main	O
,	O
Main	O
10	O
,	O
Main	O
12	O
and	O
Main	O
Still	O
Picture	O
profiles	O
of	O
HEVC	B-Algorithm
(	O
including	O
intra-only	O
profiles	O
)	O
,	O
utilizing	O
a	O
bit	O
depth	O
of	O
either	O
8	O
bits	O
or	O
10	O
bits	O
per	O
sample	O
YCbCr	O
with	O
4:2:0	O
,	O
4:2:2	O
or	O
4:4:4	O
chroma	O
subsampling	O
.	O
</s>
<s>
x265	B-Language
supports	O
most	O
of	O
the	O
features	O
of	O
x264	B-Language
including	O
all	O
rate	O
control	O
modes	O
:	O
Constant	O
QP	O
(	O
CQP	O
)	O
,	O
Constant	O
Rate	O
Factor	O
(	O
CRF	O
)	O
,	O
Average	O
Bit	O
Rate	O
(	O
ABR	O
)	O
,	O
2-pass	O
or	O
multi-pass	O
and	O
video	O
buffering	O
verifier	O
rate	O
control	O
.	O
</s>
<s>
Visual	O
quality	O
algorithms	O
include	O
CU-Tree	O
(	O
the	O
successor	O
to	O
x264	B-Language
's	O
macroblock-tree	O
)	O
,	O
adaptive	O
quantization	O
,	O
b-pyramid	O
,	O
weighted	O
prediction	O
and	O
psycho-visual	O
optimizations	O
(	O
psy-rd	O
and	O
psy-rdoq	O
)	O
.	O
</s>
<s>
Temporal	O
scalability	O
is	O
supported	O
,	O
allowing	O
for	O
a	O
video	O
to	O
be	O
encoded	O
into	O
a	O
base	O
layer	O
HEVC	B-Algorithm
bitstream	O
that	O
is	O
half	O
the	O
frame	O
rate	O
of	O
the	O
input	O
video	O
frame	O
rate	O
,	O
and	O
an	O
enhancement	O
layer	O
that	O
can	O
be	O
decoded	O
along	O
with	O
the	O
base	O
layer	O
to	O
enable	O
playback	O
at	O
the	O
full	O
frame	O
rate	O
.	O
</s>
<s>
In	O
April	O
2015	O
,	O
at	O
the	O
NAB	O
Show	O
in	O
Las	O
Vegas	O
,	O
MulticoreWare	O
demonstrated	O
high	O
quality	O
real-time	O
4K	O
10-bit	O
HEVC	B-Algorithm
encoding	O
at	O
frame	O
rates	O
in	O
excess	O
of	O
60	O
FPS	O
on	O
a	O
dual	O
Intel	O
Xeon	O
E5	O
v3	O
server	O
,	O
occupying	O
only	O
one	O
standard	O
rack	O
unit	O
.	O
</s>
<s>
Judged	O
by	O
the	O
objective	O
quality	O
metric	O
VQM	O
in	O
2015	O
,	O
x265	B-Language
delivered	O
video	O
quality	O
on	O
par	O
with	O
the	O
reference	O
encoder	O
of	O
the	O
royalty-free	O
VP9	B-Algorithm
format	O
that	O
competes	O
with	O
HEVC	B-Algorithm
.	O
</s>
<s>
A	O
codec	B-General_Concept
comparison	O
from	O
2015	O
found	O
x265	B-Language
to	O
be	O
a	O
leading	O
HEVC	B-Algorithm
implementation	O
measured	O
by	O
SSIM	B-Algorithm
metric	O
.	O
</s>
<s>
In	O
August	O
2016	O
,	O
Netflix	O
published	O
a	O
comparison	O
of	O
x264	B-Language
,	O
VP9	B-Algorithm
,	O
and	O
x265	B-Language
using	O
video	O
clips	O
from	O
500	O
movies	O
and	O
TV	O
shows	O
using	O
6	O
different	O
quality	O
metrics	O
and	O
found	O
that	O
both	O
VP9	B-Algorithm
and	O
x265	B-Language
have	O
40%	O
–	O
50%	O
better	O
quality	O
at	O
1080p	O
than	O
x264	B-Language
.	O
</s>
<s>
Netflix	O
stated	O
that	O
with	O
the	O
VMAF	B-Algorithm
metric	O
(	O
which	O
closely	O
mirrors	O
human	O
visual	O
experience	O
according	O
to	O
the	O
author	O
)	O
x265	B-Language
performed	O
substantially	O
(	O
19%	O
to	O
22%	O
)	O
better	O
than	O
VP9	B-Algorithm
.	O
</s>
<s>
x265	B-Language
can	O
be	O
invoked	O
as	O
a	O
command-line	B-Device
app	I-Device
or	O
integrated	O
into	O
another	O
application	O
through	O
the	O
application	B-Application
programming	I-Application
interface	I-Application
.	O
</s>
