<s>
Error	B-Error_Name
concealment	I-Error_Name
is	O
a	O
technique	O
used	O
in	O
signal	O
processing	O
that	O
aims	O
to	O
minimize	O
the	O
deterioration	O
of	O
signals	O
caused	O
by	O
missing	O
data	O
,	O
called	O
packet	B-Protocol
loss	I-Protocol
.	O
</s>
<s>
Packet	B-Protocol
loss	I-Protocol
occurs	O
when	O
these	O
packets	O
are	O
misdirected	O
,	O
delayed	O
,	O
resequenced	O
,	O
or	O
corrupted	O
.	O
</s>
<s>
Preliminary	O
attempts	O
at	O
receiver-based	O
error	B-Error_Name
concealment	I-Error_Name
involved	O
packet	O
repetition	O
,	O
replacing	O
lost	B-Protocol
packets	I-Protocol
with	O
copies	O
of	O
previously	O
received	O
packets	O
.	O
</s>
<s>
For	O
example	O
,	O
by	O
following	O
speech	O
patterns	O
in	O
audio	O
or	O
faces	B-General_Concept
in	O
video	O
.	O
</s>
<s>
Data	B-General_Concept
buffers	I-General_Concept
are	O
used	O
for	O
temporarily	O
storing	O
data	O
while	O
waiting	O
for	O
delayed	O
packets	O
to	O
arrive	O
.	O
</s>
<s>
Rather	O
than	O
attempting	O
to	O
recover	O
lost	B-Protocol
packets	I-Protocol
,	O
other	O
techniques	O
involve	O
anticipating	O
data	O
loss	O
,	O
manipulating	O
the	O
data	O
prior	O
to	O
transmission	O
.	O
</s>
<s>
Packet	O
repetition	O
,	O
also	O
called	O
forward	B-Error_Name
error	I-Error_Name
correction	I-Error_Name
(	O
FEC	O
)	O
,	O
adds	O
redundant	O
data	O
,	O
which	O
the	O
receiver	O
can	O
use	O
to	O
recover	O
lost	B-Protocol
packets	I-Protocol
.	O
</s>
<s>
The	O
process	O
of	O
click	O
removal	O
in	O
audio	O
restoration	O
is	O
another	O
example	O
of	O
error	B-Error_Name
concealment	I-Error_Name
.	O
</s>
