<s>
Rockbox	B-Application
is	O
a	O
free	B-License
and	I-License
open-source	I-License
software	I-License
replacement	O
for	O
the	O
OEM	O
firmware	B-Application
in	O
various	O
forms	O
of	O
digital	O
audio	O
players	O
(	O
DAPs	O
)	O
with	O
an	O
original	O
kernel	O
.	O
</s>
<s>
It	O
offers	O
an	O
alternative	O
to	O
the	O
player	O
's	O
operating	B-General_Concept
system	I-General_Concept
,	O
in	O
many	O
cases	O
without	O
removing	O
the	O
original	O
firmware	B-Application
,	O
which	O
provides	O
a	O
plug-in	B-Application
architecture	O
for	O
adding	O
various	O
enhancements	O
and	O
functions	O
.	O
</s>
<s>
Enhancements	O
include	O
personal	B-Application
digital	I-Application
assistant	I-Application
(	O
PDA	B-Application
)	O
functions	O
,	O
applications	O
,	O
utilities	O
,	O
and	O
games	O
.	O
</s>
<s>
Rockbox	B-Application
can	O
also	O
retrofit	O
video	O
playback	O
functions	O
on	O
players	O
first	O
released	O
in	O
mid-2000	O
.	O
</s>
<s>
Rockbox	B-Application
includes	O
a	O
voice-driven	O
user-interface	O
suitable	O
for	O
operation	O
by	O
visually	O
impaired	O
users	O
.	O
</s>
<s>
Rockbox	B-Application
runs	O
on	O
a	O
wide	O
variety	O
of	O
devices	O
with	O
very	O
different	O
hardware	O
abilities	O
:	O
from	O
early	O
Archos	O
players	O
with	O
1-bit	O
character	O
cell-based	O
displays	O
,	O
to	O
modern	O
players	O
with	O
high	B-Algorithm
resolution	I-Algorithm
color	O
displays	O
,	O
digital	O
optical	O
audio	O
hardware	O
and	O
advanced	O
recording	O
abilities	O
.	O
</s>
<s>
The	O
Rockbox	B-Application
project	O
began	O
in	O
late	O
2001	O
and	O
was	O
first	O
implemented	O
on	O
the	O
early	O
Archos	O
series	O
of	O
hard-disk	O
based	O
MP3	O
players/recorders	O
(	O
including	O
the	O
flash-only	O
model	O
Ondio	O
)	O
,	O
because	O
of	O
owner	O
frustration	O
with	O
severe	O
limitations	O
in	O
the	O
manufacturer-supplied	O
user	O
interface	O
and	O
device	O
operations	O
.	O
</s>
<s>
These	O
devices	O
have	O
relatively	O
weak	O
main	O
central	B-General_Concept
processing	I-General_Concept
units	I-General_Concept
(	O
CPU	O
)	O
,	O
and	O
instead	O
offload	O
music	O
playback	O
to	O
dedicated	O
hardware	O
MP3	O
decoding	O
chips	O
(	O
MAS	O
)	O
.	O
</s>
<s>
Rockbox	B-Application
was	O
unable	O
to	O
significantly	O
alter	O
playback	O
abilities	O
.	O
</s>
<s>
Instead	O
,	O
it	O
offered	O
a	O
greatly	O
improved	O
user	O
interface	O
and	O
added	O
plug-in	B-Application
functions	O
absent	O
in	O
the	O
factory	O
firmware	B-Application
.	O
</s>
<s>
Rockbox	B-Application
can	O
be	O
permanently	O
flashed	O
into	O
flash	O
memory	O
on	O
the	O
Archos	O
devices	O
,	O
making	O
it	O
a	O
firmware	B-Application
replacement	O
.	O
</s>
<s>
Versions	O
of	O
Rockbox	B-Application
have	O
since	O
been	O
produced	O
for	O
more	O
sophisticated	O
devices	O
.	O
</s>
<s>
These	O
perform	O
audio	O
decoding	O
in	O
software	B-Application
,	O
allowing	O
Rockbox	B-Application
to	O
potentially	O
support	O
many	O
more	O
music	O
formats	O
than	O
the	O
original	O
firmware	B-Application
,	O
and	O
adding	O
the	O
extensibility	O
and	O
increased	O
functions	O
already	O
present	O
in	O
the	O
Archos	O
ports	O
.	O
</s>
<s>
Rockbox	B-Application
is	O
run	O
from	O
the	O
hard	O
drive	O
or	O
flash	O
memory	O
after	O
being	O
started	O
with	O
a	O
custom	O
boot	O
loader	O
,	O
so	O
to	O
upgrade	O
Rockbox	B-Application
,	O
users	O
need	O
only	O
copy	O
the	O
files	O
onto	O
the	O
player	O
's	O
drive	O
and	O
restart	O
the	O
device	O
.	O
</s>
<s>
The	O
first	O
of	O
these	O
ports	O
,	O
beginning	O
in	O
late	O
2004	O
,	O
was	O
for	O
the	O
ColdFire-powered	O
devices	O
manufactured	O
by	O
iriver	O
,	O
focusing	O
on	O
the	O
H1xx	O
series	O
of	O
hard	O
drive	O
players	O
(	O
H110/H120/H140	O
)	O
.	O
</s>
<s>
In	O
late	O
2005	O
,	O
work	O
began	O
on	O
a	O
port	O
of	O
Rockbox	B-Application
to	O
Apple	O
's	O
iPod	B-Operating_System
portable	O
players	O
based	O
on	O
CPUs	O
from	O
ARM	B-Architecture
Ltd	I-Architecture
.	I-Architecture
incorporated	O
into	O
systems	B-Architecture
on	I-Architecture
a	I-Architecture
chip	I-Architecture
sold	O
by	O
PortalPlayer	O
.	O
</s>
<s>
Throughout	O
2006	O
,	O
Rockbox	B-Application
ports	O
were	O
made	O
available	O
for	O
a	O
variety	O
of	O
iPod	B-Operating_System
models	O
.	O
</s>
<s>
Beginning	O
in	O
2007	O
,	O
ports	O
became	O
available	O
for	O
a	O
large	O
number	O
of	O
additional	O
ARM	B-Architecture
based	O
targets	O
,	O
including	O
players	O
from	O
Sandisk	O
,	O
Toshiba	O
,	O
Olympus	O
and	O
Philips	O
in	O
addition	O
to	O
newer	O
Apple	O
and	O
iRiver	O
players	O
based	O
on	O
a	O
variety	O
of	O
ARM7	O
,	O
ARM9	O
and	O
ARM11	O
series	O
processors	O
.	O
</s>
<s>
During	O
this	O
time	O
,	O
extensive	O
work	O
was	O
conducted	O
optimizing	O
open	B-Application
source	I-Application
audio	O
decoders	O
for	O
each	O
of	O
the	O
ARM	B-Architecture
series	O
processors	O
.	O
</s>
<s>
In	O
2008	O
,	O
porting	O
began	O
to	O
processors	O
based	O
on	O
the	O
MIPS	B-Device
architecture	I-Device
.	O
</s>
<s>
In	O
2010	O
,	O
work	O
began	O
on	O
supporting	O
"	O
hosted	O
"	O
architectures	O
where	O
Rockbox	B-Application
runs	O
as	O
an	O
application	O
inside	O
of	O
more	O
complex	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
all	O
Rockbox	B-Application
ports	O
have	O
been	O
accomplished	O
by	O
reverse	O
engineering	O
with	O
little	O
or	O
no	O
manufacturer	O
assistance	O
.	O
</s>
<s>
As	O
free	O
software	B-Application
,	O
many	O
Rockbox	B-Application
developers	O
and	O
supporters	O
hope	O
to	O
eventually	O
see	O
official	O
manufacturer	O
support	O
for	O
new	O
ports	O
,	O
or	O
at	O
least	O
unofficial	O
assistance	O
in	O
porting	O
Rockbox	B-Application
to	O
new	O
devices	O
.	O
</s>
<s>
Only	O
a	O
few	O
companies	O
have	O
expressed	O
interest	O
in	O
Rockbox	B-Application
,	O
and	O
none	O
have	O
officially	O
contributed	O
code	O
to	O
the	O
project	O
or	O
included	O
it	O
with	O
their	O
hardware	O
.	O
</s>
<s>
The	O
Sansa	O
e200v1	O
port	O
is	O
the	O
first	O
to	O
be	O
started	O
at	O
the	O
request	O
of	O
the	O
hardware	O
manufacturer	O
,	O
who	O
gave	O
the	O
Rockbox	B-Application
team	O
samples	O
of	O
their	O
devices	O
.	O
</s>
<s>
Rockbox	B-Application
is	O
continuously	O
developed	O
,	O
with	O
new	O
Git	B-Application
builds	O
being	O
released	O
after	O
every	O
source	O
change	O
,	O
and	O
stable	O
releases	O
every	O
4	O
months	O
for	O
targets	O
deemed	O
sufficiently	O
mature	O
.	O
</s>
<s>
Rockbox	B-Application
is	O
targeted	O
primarily	O
at	O
digital	O
audio	O
players	O
,	O
rather	O
than	O
the	O
much	O
more	O
powerful	O
general-purpose	O
devices	O
(	O
such	O
as	O
smartphones	B-Application
and	O
tablet	B-Device
computers	I-Device
)	O
that	O
have	O
been	O
increasing	O
in	O
popularity	O
since	O
2010	O
.	O
</s>
<s>
Daniel	O
Stenberg	O
,	O
a	O
founder	O
of	O
the	O
Rockbox	B-Application
project	O
,	O
envisions	O
the	O
project	O
evolving	O
away	O
from	O
a	O
standalone	O
Rockbox	B-Application
operating	B-General_Concept
system	I-General_Concept
to	O
Rockbox	B-Application
as	O
a	O
media	O
player	O
application	O
that	O
runs	O
under	O
mobile	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
,	O
such	O
as	O
Android	B-Application
,	O
iOS	B-Operating_System
,	O
Sailfish	B-Operating_System
OS	I-Operating_System
or	O
Tizen	B-Application
:	O
</s>
<s>
A	O
project	O
to	O
port	O
Rockbox	B-Application
to	O
run	O
as	O
an	O
application	O
under	O
a	O
full-fledged	O
operating	B-General_Concept
system	I-General_Concept
was	O
accepted	O
for	O
Google	B-Application
's	I-Application
2010	O
Summer	B-Application
of	I-Application
Code	I-Application
and	O
completed	O
.	O
</s>
<s>
Currently	O
,	O
Rockbox	B-Application
runs	O
on	O
Android	B-Application
based	O
players	O
,	O
but	O
integration	O
into	O
Android	B-Application
and	O
conversion	O
to	O
work	O
with	O
touch	O
based	O
devices	O
is	O
ongoing	O
.	O
</s>
<s>
Subsequently	O
,	O
an	O
anonymous	O
Chinese	O
developer	O
unofficially	O
ported	O
Rockbox	B-Application
to	O
Palm	O
's	O
WebOS	B-Operating_System
.	O
</s>
<s>
Subject	O
to	O
the	O
limitations	O
of	O
each	O
particular	O
platform	O
,	O
the	O
appearance	O
of	O
Rockbox	B-Application
can	O
be	O
customised	O
in	O
various	O
ways	O
.	O
</s>
<s>
Rockbox	B-Application
has	O
essentially	O
been	O
a	O
file-tree	O
based	O
player	O
,	O
to	O
which	O
folders	O
could	O
be	O
dragged	O
and	O
dropped	O
and	O
then	O
navigated	O
by	O
folder	O
structure	O
.	O
</s>
<s>
Rockbox	B-Application
has	O
many	O
features	O
additional	O
to	O
those	O
supported	O
by	O
the	O
original	O
operating	O
firmware	B-Application
,	O
but	O
in	O
many	O
cases	O
there	O
are	O
limitations	O
.	O
</s>
<s>
On	O
platforms	O
classified	O
as	O
"	O
stable	O
"	O
and	O
supported	O
,	O
the	O
device	O
can	O
be	O
used	O
as	O
a	O
digital	O
music	O
player	O
,	O
but	O
even	O
on	O
some	O
such	O
platforms	O
Rockbox	B-Application
does	O
not	O
support	O
charging	O
or	O
USB	O
;	O
the	O
player	O
must	O
be	O
dual-booted	O
into	O
the	O
original	O
firmware	B-Application
to	O
be	O
charged	O
or	O
to	O
transfer	O
files	O
.	O
</s>
<s>
Rockbox	B-Application
on	O
software	B-Application
decoding	O
platforms	O
(	O
non-Archos	O
)	O
supports	O
playback	O
of	O
twelve	O
lossy	B-Algorithm
codecs	O
(	O
depending	O
on	O
how	O
one	O
counts	O
)	O
,	O
five	O
lossless	B-Algorithm
,	O
two	O
uncompressed	O
and	O
twelve	O
miscellaneous	O
formats	O
.	O
</s>
<s>
Extensive	O
work	O
has	O
gone	O
into	O
optimizing	O
each	O
codec	O
,	O
with	O
FLAC	B-Application
,	O
Ogg	B-Algorithm
Vorbis	I-Algorithm
,	O
WMA	B-Application
,	O
APE	B-Language
,	O
TTA	B-Algorithm
,	O
MPC	B-Algorithm
,	O
Wavpack	B-Application
,	O
ATRAC3	O
,	O
Cook	B-Algorithm
and	O
WMA	B-Application
Pro	O
among	O
the	O
fastest	O
known	O
integer	O
implementations	O
for	O
those	O
formats	O
.	O
</s>
<s>
Together	O
they	O
include	O
over	O
a	O
dozen	O
different	O
PCM	B-Algorithm
and	O
ADPCM	B-Algorithm
formats	O
.	O
</s>
<s>
In	O
addition	O
,	O
there	O
are	O
playback	O
of	O
game	O
audio	O
types	O
ADX	B-Algorithm
,	O
SID	O
,	O
NSF	O
,	O
SAP	O
,	O
SPC	O
,	O
AY	O
,	O
GBS	O
,	O
HES	O
,	O
KSS	O
,	O
SGC	O
,	O
VGM	O
,	O
and	O
VGZ	O
.	O
</s>
<s>
The	O
MOD	O
tracker	B-Application
format	O
,	O
and	O
the	O
Yamaha	O
SMAF	O
are	O
also	O
now	O
supported	O
.	O
</s>
<s>
Some	O
profiles	O
in	O
Monkey	B-Language
's	I-Language
Audio	I-Language
are	O
not	O
real	O
time	O
on	O
all	O
targets	O
due	O
to	O
very	O
high	O
CPU	O
needs	O
.	O
</s>
<s>
Also	O
,	O
Rockbox	B-Application
will	O
not	O
play	O
files	O
with	O
a	O
digital	O
rights	O
management	O
(	O
DRM	O
)	O
scheme	O
.	O
</s>
<s>
Beside	O
the	O
ability	O
of	O
playing	O
and	O
recording	O
audio	O
files	O
,	O
Rockbox	B-Application
offers	O
many	O
playback	O
enhancements	O
that	O
other	O
firmware	B-Application
packages	O
may	O
not	O
have	O
implemented	O
yet	O
.	O
</s>
<s>
Rockbox	B-Application
developers	O
can	O
create	O
plug-ins	B-Application
,	O
which	O
provide	O
the	O
user	O
with	O
other	O
enhancements	O
that	O
may	O
not	O
be	O
available	O
on	O
various	O
firmware	B-Application
modules	O
.	O
</s>
<s>
Available	O
plug-ins	B-Application
include	O
:	O
</s>
<s>
Rockbox	B-Application
uses	O
a	O
simple	O
kernel	O
,	O
with	O
a	O
flat	B-General_Concept
memory	I-General_Concept
model	I-General_Concept
and	O
single	O
process	B-Operating_System
,	O
letting	O
it	O
run	O
on	O
platforms	O
without	O
a	O
memory	B-General_Concept
management	I-General_Concept
unit	I-General_Concept
.	O
</s>
<s>
Thin	O
threads	B-Operating_System
run	O
cooperatively	B-Operating_System
,	O
returning	O
control	O
to	O
a	O
scheduler	O
that	O
prioritizes	O
the	O
audio	O
thread	B-Operating_System
;	O
the	O
only	O
form	O
of	O
preemption	B-Operating_System
is	O
through	O
interrupts	B-Application
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
and	O
plug-ins	B-Application
are	O
written	O
in	O
C	B-Language
,	O
with	O
assembly	B-Language
used	O
for	O
code	O
that	O
is	O
device	O
-	O
and	O
platform-specific	O
,	O
and	O
performance	O
sensitive	O
.	O
</s>
<s>
The	O
simple	O
and	O
lightweight	O
architecture	O
allows	O
Rockbox	B-Application
to	O
run	O
on	O
a	O
variety	O
of	O
targets	O
,	O
with	O
memory	O
ranging	O
from	O
1	O
to	O
64	O
MB	O
,	O
and	O
CPU	O
speeds	O
ranging	O
12	O
to	O
532MHz	O
.	O
</s>
<s>
Rockbox	B-Application
also	O
provides	O
support	O
for	O
multicore	O
and	O
asymmetric	B-Operating_System
multiprocessor	I-Operating_System
systems	O
based	O
on	O
ARM	B-Architecture
,	O
ColdFire	B-Device
,	O
MIPS	B-Device
and	O
SH	O
.	O
</s>
<s>
The	O
Rockbox	B-Application
Utility	O
is	O
a	O
free	O
computer	O
application	O
,	O
available	O
for	O
Linux	B-Application
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
and	O
Microsoft	B-Application
Windows	I-Application
,	O
built	O
using	O
Digia	O
Qt	B-Language
platform	O
,	O
that	O
is	O
used	O
to	O
install	O
and	O
manage	O
Rockbox	B-Application
on	O
DAPs	O
.	O
</s>
<s>
Rockbox	B-Application
Utility	O
provides	O
automatic	O
installation	O
of	O
Rockbox	B-Application
,	O
as	O
well	O
as	O
themes	O
and	O
voice	O
files	O
,	O
directly	O
onto	O
a	O
DAP	O
with	O
minimal	O
user	O
interaction	O
.	O
</s>
<s>
Rockbox	B-Application
Utility	O
is	O
updated	O
frequently	O
as	O
support	O
for	O
new	O
devices	O
is	O
added	O
.	O
</s>
