<s>
libvpx	B-Language
is	O
a	O
free	B-Application
software	I-Application
video	B-Application
codec	I-Application
library	B-Library
from	O
Google	B-Application
and	O
the	O
Alliance	O
for	O
Open	O
Media	O
(	O
AOMedia	O
)	O
.	O
</s>
<s>
It	O
serves	O
as	O
the	O
reference	O
software	O
implementation	O
for	O
the	O
VP8	B-Algorithm
and	O
VP9	B-Algorithm
video	O
coding	O
formats	O
,	O
and	O
for	O
AV1	B-Application
a	O
special	O
fork	B-Application
named	O
libaom	B-Language
that	O
was	O
stripped	O
of	O
backwards	O
compatibility	O
.	O
</s>
<s>
As	O
free	B-Application
software	I-Application
it	O
is	O
published	O
also	O
in	O
source	O
code	O
under	O
the	O
terms	O
of	O
the	O
revised	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
It	O
ships	O
with	O
the	O
commandline	B-Application
tools	I-Application
vpxenc/aomenc	O
and	O
vpxdec/aomdec	O
that	O
build	O
on	O
its	O
functionality	O
.	O
</s>
<s>
libvpx	B-Language
originates	O
from	O
the	O
video	B-Application
codec	I-Application
company	O
On2	B-Application
Technologies	I-Application
that	O
sold	O
its	O
first	O
software	O
codec	O
in	O
mid-90s	O
.	O
</s>
<s>
libvpx	B-Language
was	O
released	O
as	O
free	B-Application
software	I-Application
by	O
Google	B-Application
on	O
May	O
19	O
,	O
2010	O
,	O
after	O
the	O
acquisition	O
of	O
On2	B-Application
Technologies	I-Application
for	O
an	O
estimate	O
of	O
over	O
120	O
million	O
US	O
dollars	O
.	O
</s>
<s>
Google	B-Application
was	O
criticised	O
for	O
dumping	O
untidy	O
code	O
with	O
bad	O
documentation	O
for	O
the	O
initial	O
release	O
of	O
libvpx	B-Language
and	O
developing	O
behind	O
closed	O
doors	O
without	O
involving	O
the	O
community	O
in	O
the	O
process	O
.	O
</s>
<s>
The	O
development	O
process	O
was	O
opened	O
after	O
the	O
release	O
of	O
VP9	B-Algorithm
.	O
</s>
<s>
Preliminary	O
support	O
for	O
VP9	B-Algorithm
was	O
added	O
to	O
libvpx	B-Language
on	O
June	O
17	O
,	O
2013	O
.	O
</s>
<s>
It	O
was	O
officially	O
introduced	O
with	O
the	O
release	O
of	O
version	O
1.3	O
on	O
December	O
2	O
,	O
which	O
also	O
supports	O
lossless	B-Algorithm
compression	I-Algorithm
.	O
</s>
<s>
In	O
April	O
2015	O
,	O
Google	B-Application
released	O
a	O
significant	O
update	O
to	O
its	O
libvpx	B-Language
library	B-Library
,	O
with	O
version	O
1.4.0	O
adding	O
support	O
for	O
encoding	O
VP9	B-Algorithm
with	O
10-bit	O
and	O
12-bit	O
bit	O
depth	O
,	O
4:2:2	O
and	O
4:4:4	O
chroma	O
subsampling	O
(	O
VP9	B-Algorithm
profiles	O
1	O
,	O
2	O
,	O
and	O
3	O
)	O
,	O
and	O
VP9	B-Algorithm
multithreaded	O
decoding/encoding	O
.	O
</s>
<s>
libvpx	B-Language
implements	O
single-pass	O
and	O
two-pass	O
encoding	O
modes	O
,	O
with	O
either	O
bitrate	O
or	O
quality	O
target	O
settings	O
.	O
</s>
<s>
libvpx	B-Language
offers	O
an	O
asymmetric	O
codec	O
–	O
with	O
encoding	O
taking	O
much	O
longer	O
than	O
decoding	O
–	O
and	O
options	O
for	O
configuring	O
encoding	O
expense	O
independently	O
from	O
decoding	O
complexity	O
.	O
</s>
<s>
libvpx	B-Language
includes	O
a	O
mode	O
where	O
the	O
maximum	O
CPU	O
resources	O
possible	O
will	O
be	O
used	O
while	O
still	O
keeping	O
the	O
encoding	O
speed	O
almost	O
exactly	O
equivalent	O
to	O
the	O
playback	O
speed	O
(	O
realtime	O
)	O
,	O
keeping	O
the	O
quality	O
as	O
high	O
as	O
possible	O
without	O
lag	O
.	O
</s>
<s>
libvpx	B-Language
supports	O
Rec	O
.	O
</s>
<s>
2020	O
,	O
SMPTE-170	O
,	O
SMPTE-240	O
,	O
and	O
sRGB	O
color	B-Algorithm
spaces	I-Algorithm
.	O
</s>
<s>
At	O
high	O
resolutions	O
(	O
e.g.	O
,	O
UHD	B-Device
)	O
VP9	B-Algorithm
encoded	O
by	O
libvpx	B-Language
for	O
VOD	O
applications	O
provides	O
a	O
significant	O
improvement	O
over	O
H.264	B-Application
encoded	O
by	O
x264	B-Language
.	O
</s>
<s>
HEVC	B-Algorithm
encoded	O
by	O
x265	B-Language
may	O
achieve	O
even	O
better	O
quality	O
,	O
but	O
the	O
royalty-free	O
nature	O
of	O
VP9	B-Algorithm
makes	O
it	O
a	O
compelling	O
option	O
for	O
delivering	O
high	O
resolution	O
video	O
on	O
supported	O
platforms	O
.	O
</s>
<s>
Compared	O
to	O
the	O
initial	O
release	O
of	O
libvpx	B-Language
,	O
ffvp8	O
from	O
the	O
FFmpeg	O
project	O
improved	O
performance	O
by	O
22	O
to	O
over	O
66%	O
.	O
</s>
<s>
In	O
2016	O
,	O
alternative	O
VP9	B-Algorithm
decoders	O
still	O
achieved	O
25	O
–	O
50%	O
faster	O
decoding	O
.	O
</s>
<s>
libvpx	B-Language
is	O
written	O
in	O
C	B-Language
and	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
It	O
does	O
not	O
have	O
complete	O
SIMD	B-Device
coverage	O
as	O
of	O
2015	O
.	O
</s>
<s>
libvpx	B-Language
is	O
used	O
by	O
major	O
OTT	O
video	O
services	O
including	O
YouTube	B-General_Concept
,	O
Netflix	O
,	O
Amazon	B-Application
,	O
JW	O
Player	O
,	O
Brightcove	O
,	O
and	O
Telestream	O
,	O
among	O
which	O
are	O
the	O
biggest	O
sources	O
of	O
internet	O
traffic	O
with	O
Netflix	O
alone	O
accounting	O
for	O
nearly	O
a	O
third	O
of	O
all	O
internet	O
traffic	O
in	O
the	O
United	O
States	O
as	O
of	O
2017	O
.	O
</s>
<s>
There	O
are	O
alternatives	O
for	O
decoding	O
VP8	B-Algorithm
and	O
VP9	B-Algorithm
,	O
both	O
commercial	O
and	O
closed	O
source	O
as	O
well	O
as	O
open	O
source	O
.	O
</s>
<s>
For	O
encoding	O
there	O
are	O
only	O
commercial	O
alternatives	O
and	O
some	O
unfinished	O
experimental	O
software	O
for	O
VP8	B-Algorithm
including	O
xvp8	O
as	O
of	O
2016	O
.	O
</s>
