<s>
Media	B-Language
Source	I-Language
Extensions	I-Language
(	O
MSE	O
)	O
is	O
a	O
W3C	O
specification	O
that	O
allows	O
JavaScript	B-Language
to	O
send	O
byte	O
streams	O
to	O
media	B-General_Concept
codecs	I-General_Concept
within	O
Web	B-Application
browsers	I-Application
that	O
support	O
HTML5	B-Application
video	O
and	O
audio	B-Language
.	O
</s>
<s>
Among	O
other	O
possible	O
uses	O
,	O
this	O
allows	O
the	O
implementation	O
of	O
client-side	O
prefetching	O
and	O
buffering	O
code	O
for	O
streaming	O
media	O
entirely	O
in	O
JavaScript	B-Language
.	O
</s>
<s>
It	O
is	O
compatible	O
with	O
,	O
but	O
should	O
not	O
be	O
confused	O
with	O
,	O
the	O
Encrypted	B-Language
Media	I-Language
Extensions	I-Language
(	O
EME	B-Language
)	O
specification	O
,	O
and	O
neither	O
requires	O
the	O
use	O
of	O
the	O
other	O
,	O
although	O
many	O
EME	B-Language
implementations	O
are	O
only	O
capable	O
of	O
decrypting	O
media	O
data	O
provided	O
via	O
MSE	O
.	O
</s>
<s>
Netflix	O
announced	O
experimental	O
support	O
in	O
June	O
2014	O
for	O
the	O
use	O
of	O
MSE	O
playback	O
on	O
the	O
Safari	B-Application
browser	I-Application
on	O
the	O
OS	B-Device
X	I-Device
Yosemite	I-Device
beta	O
release	O
.	O
</s>
<s>
YouTube	B-General_Concept
started	O
using	O
MSE	O
with	O
its	O
HTML5	B-Application
player	O
in	O
September	O
2013	O
.	O
</s>
<s>
Media	B-Language
Source	I-Language
Extensions	I-Language
API	B-General_Concept
is	O
widely	O
supported	O
across	O
all	O
modern	O
web	B-Application
browsers	I-Application
,	O
with	O
the	O
only	O
exception	O
being	O
iPhone-family	O
devices	O
(	O
although	O
it	O
is	O
supported	O
on	O
iPadOS	O
)	O
.	O
</s>
<s>
as	O
a	O
contributor	O
to	O
the	O
and	O
DASH.js	O
(	O
DASH	B-Protocol
IF	O
reference	O
client	O
)	O
.	O
</s>
<s>
Azure	B-Application
Media	O
Player	O
supports	O
MSE	O
,	O
EME	B-Language
,	O
DASH	B-Protocol
,	O
HLS	B-Protocol
,	O
Flash	B-Operating_System
,	O
and	O
Silverlight	B-Application
.	O
</s>
