<s>
Bitrate	B-General_Concept
peeling	I-General_Concept
is	O
a	O
technique	O
used	O
in	O
Ogg	B-Algorithm
Vorbis	I-Algorithm
audio	O
encoded	B-General_Concept
streams	O
,	O
wherein	O
a	O
stream	O
can	O
be	O
encoded	B-General_Concept
at	O
one	O
bitrate	O
but	O
can	O
be	O
served	O
at	O
that	O
or	O
any	O
lower	O
bitrate	O
.	O
</s>
<s>
The	O
server	B-Application
automatically	O
chooses	O
which	O
stream	O
to	O
deliver	O
to	O
the	O
user	O
,	O
depending	O
on	O
user	O
's	O
connection	O
speed	O
.	O
</s>
<s>
,	O
Ogg	B-Algorithm
Vorbis	I-Algorithm
bitrate	B-General_Concept
peeling	I-General_Concept
existed	O
only	O
as	O
a	O
concept	O
as	O
there	O
was	O
not	O
yet	O
an	O
encoder	O
capable	O
of	O
producing	O
peelable	O
datastreams	O
.	O
</s>
<s>
The	O
difference	O
between	O
SureStream	O
and	O
bitrate	B-General_Concept
peeling	I-General_Concept
is	O
that	O
SureStream	O
is	O
limited	O
to	O
only	O
a	O
handful	O
of	O
pre-defined	O
bitrates	O
,	O
with	O
significant	O
difference	O
between	O
them	O
,	O
and	O
SureStream	O
encoded	B-General_Concept
files	O
are	O
big	O
because	O
they	O
contain	O
all	O
of	O
the	O
bitrates	O
used	O
,	O
while	O
bitrate	B-General_Concept
peeling	I-General_Concept
uses	O
much	O
smaller	O
steps	O
to	O
change	O
the	O
available	O
bitrate	O
and	O
quality	O
,	O
and	O
only	O
the	O
highest	O
bitrate	O
is	O
used	O
to	O
encode	O
the	O
file/stream	O
,	O
which	O
results	O
in	O
smaller	O
files	O
on	O
servers	O
.	O
</s>
<s>
A	O
related	O
technique	O
to	O
the	O
SureStream	O
approach	O
is	O
hierarchical	B-Protocol
modulation	I-Protocol
,	O
used	O
in	O
broadcast	O
,	O
where	O
severally	O
different	O
streams	O
at	O
different	O
qualities	O
(	O
and	O
bitrates	O
)	O
are	O
all	O
broadcast	O
,	O
with	O
the	O
higher	O
quality	O
stream	O
used	O
if	O
possible	O
,	O
with	O
the	O
lower	O
quality	O
streams	O
fallen	O
back	O
on	O
if	O
not	O
.	O
</s>
<s>
Such	O
formats	O
include	O
MPEG-4	O
SLS	O
(	O
scalable	O
to	O
lossless	O
)	O
,	O
WavPack	B-Application
,	O
DTS-HD	O
Master	O
Audio	O
and	O
OptimFROG	O
DualStream	O
.	O
</s>
<s>
A	O
SureStream	O
encoded	B-General_Concept
file	O
is	O
encoded	B-General_Concept
at	O
bitrates	O
of	O
16kbit/s	O
,	O
32kbit/s	O
and	O
96kbit/s	O
.	O
</s>
<s>
The	O
file	O
will	O
be	O
about	O
the	O
same	O
in	O
size	O
as	O
three	O
separate	O
files	O
encoded	B-General_Concept
at	O
those	O
bitrates	O
and	O
put	O
together	O
,	O
or	O
one	O
file	O
encoded	B-General_Concept
at	O
the	O
sum	O
of	O
those	O
bitrates	O
,	O
which	O
is	O
about	O
144kbit/s	O
(	O
16	O
+	O
32	O
+	O
96	O
)	O
.	O
</s>
<s>
When	O
a	O
dial-up	O
user	O
has	O
only	O
about	O
28kbit/s	O
of	O
bandwidth	O
available	O
,	O
the	O
Real	O
server	B-Application
will	O
serve	O
the	O
16kbit/s	O
stream	O
.	O
</s>
<s>
If	O
the	O
dial-up	O
connection	O
is	O
of	O
higher	O
quality	O
,	O
and	O
maybe	O
about	O
42kbit/s	O
is	O
available	O
,	O
the	O
server	B-Application
will	O
automatically	O
switch	O
to	O
the	O
32kbit/s	O
stream	O
.	O
</s>
<s>
A	O
DSL	O
or	O
cable	B-Device
Internet	O
user	O
will	O
be	O
served	O
the	O
96kbit/s	O
stream	O
.	O
</s>
<s>
This	O
looks	O
good	O
,	O
but	O
even	O
though	O
the	O
user	O
with	O
28kbit/s	O
can	O
use	O
a	O
higher	O
bitrate	O
/	O
higher	O
quality	O
stream	O
(	O
maybe	O
22	O
–	O
24kbit/s	O
)	O
,	O
such	O
thing	O
ca	O
n't	O
be	O
done	O
with	O
SureStream	O
,	O
unless	O
the	O
encoded	B-General_Concept
file	O
contains	O
such	O
a	O
bitrate	O
.	O
</s>
<s>
This	O
is	O
where	O
Bitrate	B-General_Concept
Peeling	I-General_Concept
comes	O
into	O
play	O
.	O
</s>
<s>
Contrary	O
to	O
SureStream	O
,	O
bitrate	B-General_Concept
peeling	I-General_Concept
requires	O
only	O
the	O
highest	O
bitrate	O
to	O
be	O
used	O
when	O
encoding	O
a	O
file/stream	O
,	O
which	O
is	O
96kbit/s	O
in	O
this	O
case	O
.	O
</s>
<s>
The	O
obvious	O
benefit	O
is	O
much	O
smaller	O
space	O
on	O
a	O
server	B-Application
required	O
by	O
such	O
a	O
file	O
.	O
</s>
<s>
An	O
additional	O
feature	O
of	O
bitrate	B-General_Concept
peeling	I-General_Concept
is	O
a	O
much	O
finer	O
tuning	O
of	O
available	O
bitrate/quality	O
.	O
</s>
<s>
If	O
a	O
dial-up	O
user	O
with	O
28kbit/s	O
available	O
bandwidth	O
connects	O
to	O
an	O
Ogg	B-Algorithm
Vorbis	I-Algorithm
file/stream	O
,	O
the	O
server	B-Application
will	O
"	O
peel	O
"	O
the	O
original	O
96kbit/s	O
file/stream	O
down	O
to	O
just	O
below	O
available	O
bandwidth	O
(	O
in	O
this	O
case	O
it	O
would	O
be	O
around	O
20	O
–	O
24kbit/s	O
)	O
.	O
</s>
<s>
This	O
so-called	O
peeling	O
process	O
is	O
different	O
from	O
transcoding	B-Algorithm
because	O
transcoding	B-Algorithm
uncompresses	O
the	O
file	O
and	O
recompresses	O
it	O
(	O
a	O
computing-intensive	O
process	O
)	O
,	O
whereas	O
the	O
peeling	O
process	O
removes	O
excess	O
bits	O
from	O
the	O
stream	O
without	O
more	O
processing	O
.	O
</s>
<s>
Aside	O
from	O
the	O
obvious	O
space-saving	O
advantage	O
bitrate	B-General_Concept
peeling	I-General_Concept
allows	O
for	O
smaller	O
steps	O
in	O
the	O
delivery	O
bitrate	O
(	O
the	O
end	O
user	O
will	O
see	O
the	O
file	O
in	O
the	O
highest	O
quality	O
possible	O
for	O
their	O
bandwidth	O
)	O
.	O
</s>
<s>
These	O
benefits	O
are	O
only	O
theoretical	O
,	O
as	O
the	O
only	O
Vorbis	B-Algorithm
peeler	O
available	O
is	O
still	O
in	O
experimental	O
state	O
and	O
produces	O
file	O
qualities	O
inferior	O
to	O
what	O
transcoding	B-Algorithm
the	O
higher	O
bitrate	O
file	O
to	O
a	O
lower	O
bitrate	O
would	O
.	O
</s>
<s>
Bitrate	B-General_Concept
peeling	I-General_Concept
is	O
theoretically	O
possible	O
,	O
and	O
is	O
implemented	O
in	O
some	O
other	O
formats	O
,	O
notably	O
JPEG	O
2000	O
,	O
JPEG	O
progressive	O
encoding	O
,	O
and	O
Scalable	B-Application
Video	I-Application
Coding	I-Application
.	O
</s>
<s>
The	O
reason	O
that	O
it	O
is	O
not	O
available	O
in	O
Ogg	B-Algorithm
Vorbis	I-Algorithm
is	I-Algorithm
that	O
current	O
encoders	O
do	O
not	O
organize	O
the	O
code-stream	O
to	O
have	O
progressive	O
accuracy	O
,	O
thus	O
peelers	O
cannot	O
tell	O
which	O
data	O
is	O
more	O
or	O
less	O
important	O
.	O
</s>
<s>
See	O
also	O
the	O
Adam7	B-Algorithm
algorithm	I-Algorithm
used	O
in	O
PNG	O
interlacing	O
.	O
</s>
